pathogenic and opportunistic bacteria:
abiotrophia species:
Abiotrophia species are nutritionally variant streptococci (Gram-positive) that occasionally cause opportunistic endocarditis but are rarely encountered in infections of other sterile sites.
acinetobacter baumannii complex:
Acinetobacter baumannii complex is a Gram-negative coccobacillus that is oxidase-negative, indole negative, catalase positive, and exhibits twitching motility in wet mount, though it is nonmotile in motility agar. It is a non-fermenter on MacConkey agar but some strains are partial lactose-fermenters. It is a soil bacterium that causes rare infections in humans, and is often multi-drug-resistant. It is a major source of infection in hospitalized patients (nosocomial), especially those in the ICU. It is a strict aerobe, and it is nitrate negative. It does ferment glucose.
Some strains, especially A. calcoaceticus, are mucoid and slimy with smooth, rounded colonies at 37 degrees Celsius. This strain ferments glucose and is non hemolytic. A. lwofii does not ferment glucose and is also non hemolytic. A. haemolyticus is beta-hemolytic.
Infections that are caused by this organism include UTI, pneumonia, wound, ventilator-associated pneumonia, skin infections, bacteremia, infective carditis, burn infection, keratitis, peritonitis, rare neonatal sepsis and meningitis (A. lowfii).
The bacterium grows very well on meat extract and CHOC agar. It produces glistening white, shiny, convex, smooth, moist, viscoid colonies, It does not ferment carbohydrates. It is a rapid-grower that is catalase positive and oxidase negative and tends to be resistant to penicillin.
Some strains, especially A. calcoaceticus, are mucoid and slimy with smooth, rounded colonies at 37 degrees Celsius. This strain ferments glucose and is non hemolytic. A. lwofii does not ferment glucose and is also non hemolytic. A. haemolyticus is beta-hemolytic.
Infections that are caused by this organism include UTI, pneumonia, wound, ventilator-associated pneumonia, skin infections, bacteremia, infective carditis, burn infection, keratitis, peritonitis, rare neonatal sepsis and meningitis (A. lowfii).
The bacterium grows very well on meat extract and CHOC agar. It produces glistening white, shiny, convex, smooth, moist, viscoid colonies, It does not ferment carbohydrates. It is a rapid-grower that is catalase positive and oxidase negative and tends to be resistant to penicillin.
Actinomyces species:
Actinomyces species are anaerobic Gram-positive bacilli in thin, filamentous, branching, beaded or banding formations that are usually associated with mixed oral or cervicofacial, thoracic, pelvic, or abdominal infections caused by the patient's own microflora. Some strains are linked to cervicofacial infections involving periodontal disease and dental cavities as well. Thoracic actinomycoses cause infections of the lungs, cause abscesses, or lead to draining sinuses. Abdominal actinomycoses lead to abdominal infections or abscesses. It does not possess any well-known virulence factors, and infections are caused by disruption of the mucous membranes of the oral cavity, respiratory tract, GI tract or female genitourinary tract.
Under the microscope, you can expect to see Gram-positive, beaded, filamentous rods. Sometimes, if you are examining a pus specimen, you will see golden sulfur granules under the microscope as well.
On ANABAP agar, colonies of the bacterium grow as small, smooth, convex, gray-white, translucent, round, sometimes "molar tooth-like", and may or may not be beta-hemolytic.
Species include:
Under the microscope, you can expect to see Gram-positive, beaded, filamentous rods. Sometimes, if you are examining a pus specimen, you will see golden sulfur granules under the microscope as well.
On ANABAP agar, colonies of the bacterium grow as small, smooth, convex, gray-white, translucent, round, sometimes "molar tooth-like", and may or may not be beta-hemolytic.
Species include:
- A. israelii is the most cause of actinomycosis, which is nonmotile and non-acid-fast
- In THIO, will show a zone band of flocculent or granular growth about 1 cm below the surface with a clear area above it
- It does not ferment mannitol, xylose or salicin
- Catalase negative
- A. meyeri
- A. naeslundii
- A. odontolyticus
- A. viscosus
- Only Actinomyces species that is catalase +
- A. gerencseriae
- Penicillin G
- Surgical Drainage
aerococcus urinae:
Aerococcus urinae are Gram-positive cocci (large), catalase-negative bacteria associated with urinary tract infections (UTIs). These infections may actually become invasive, resulting in urosepsis and infective endocarditis. Elderly men with underlying urinary tract diseases are particularly at risk for infection with this organism. Luckily, it is susceptible to many of the most common antibiotics, including penicillin, the cephalosporins and vancomycin. Antibiotic resistance is on the rise, however, especially to many of the common antibiotics typically given specifically for urinary tract infections (UTIs), like ciprofloxacin, trimethoprim-sulfaxazole, and nitrofurantoin. Part of the reason behind its virulence is its ability to form biofilms and colonize equipment, and its ability to coagulate platelets. A. sanguinicola is another strain that is occasionally isolated from urine and/or blood and is also associated with rare UTIs and infective endocarditis.
Aggregatibacter (previously actinobacillus):
Aggregatibacter, or Actinobacillus, is part of the HACEK group of bacteria and is a normal part of the human commensal microflora of the oropharynx. It is Gram-negative coccobacilli, nonmotile, non-spore-forming, and is aerobic or a facultative anaerobe. It ferments sugars without gas production. It also reduces nitrates to nitrite. It causes several opportunistic infections, including sinusitis, bronchopneumonia, meningitis, and endocarditis. It is susceptible to most of the beta-lactam antibiotics.
aeromonas hydrophila:
Aeromonas hydrophila is a bacterium that is found in moist, aquatic environments. It causes human infections by colonizing open wounds or through ingestion of contaminated water or foods, where it sticks to the intestinal mucosa and produces an enterotoxin that causes watery diarrhea. When it infects a wound, it may cause local infection or spread throughout the surrounding tissue, resulting in cellulitis. If it penetrates a deep wound, it can become more serious, resulting in an infection similar to gas gangrene called myonecrosis. This can quickly become serious if it results in bacteremia or sepsis and becomes toxic to the entire body by causing systemic infection. These types of infections can be fatal, particularly in patients who are already immunocompromised, or suffering from cancers such as leukemia or lymphoma. The microbiologist will most likely see this organism on the stools bench. Talk with other benches to see if positive cultures have occurred across many cultures (urine, sterile, blood, etc...).
Characteristics:
Characteristics:
- Gram-negative rod on Gram stain
- Beta-hemolytic
- Large convex, smooth, mucoid, tan colonies
- Motile
- Facultative Anaerobe
- Ferments sucrose and mannitol
- ONPG positive
- Indole positive
- Lysine decarboxylase positive
- Bile esculin positive
- Ornithine decarboxylase negative
- Cultures: aerobic and anaerobic blood, stool, and wound
- Cephalosporins (3rd generation)
- Trimethroprim
- Sulfa drugs
- Fluoroquinolones
alloiococcus species:
Alloiococcus species are Gram-positive cocci that cause rare opportunistic chronic otitis media in children.
Characteristics:
Characteristics:
- GPC in singles, pairs, or tetrads
- Non-hemolytic
- Catalase +
- PYR +
- Resembles viridian's streptococci
arcanobacterium haemolyticum:
Arcanobacterium haemolyticum is a bacterium infection that can cause opportunistic infections in humans, namely acute pharyngitis or peritonsillar abscess. It can also cause a rash on the trunk that is scarlet-like, erthyemous, or morbilliform in nature. The microbiologist will most likely see this organism on the throats bench.
Characteristics:
Characteristics:
- Gram-positive bacilli
- Usually beta-hemolytic
- Non-acid-fast
- Non-motile
- Facultative anaerobe
- Do not form spores
- Found in the human microflora
- Found in animal microflora
- Means "secret bacterium"
- Colonies are small, golden, beta-hemolytic, and resemble S. pyogenes, however, they are Gram-positive rods in Gram-stain rather than cocci
bacillus cereus:
B. cereus is a pathogen that can cause food poisoning and severe eye infections. The microbiologist will most likely see this organism on the stools bench or the respiratory bench (since this bench usually works up eye and ear cultures as well). The ocular (eye) infections are a result of the secretion and interaction of three toxins by the bacterium: necrotic toxin, cereolysin, and phospholipase C. It causes a very rapidly destructive infection of the eye following trauma to the eye. Those at higher risk for this type of infection include those who are immunocompromised, farmers, and IV drug users.
Characteristics:
- Necrotic toxin: heat-labile enterotoxin
- Cereolysin: hemolysin enzyme
- Phospholipase C: lecithinase enzyme
- Emetic form is caused by heat-stable enterotoxin and occurs just 1-6 hours after eating contaminated food. This illness comes quickly but is over in <24 hours. It usually happens when someone eats cooked rice that has not been properly refrigerated within 2 hours. The spores survive the initial cooking process, and when left at room temperature, rapidly germinate and multiply into vegetative forms that release the toxin, resulting in stomach cramps, nausea and vomiting.
- The diarrheal form is caused by heat-labile enterotoxin, and it occurs about 9 hours after eating contaminated meat, sauce or vegetables. This type lasts 24-36 hours.
Characteristics:
- Gram-positive bacilli (thick rods)
- Spore-forming
- Non-encapsulated
- Motile (gliding motility)
- Large, rough, irregular, grayish-white umbonate colonies
- Facultative anaerobe
- Produces acid from glucose, maltose, salicin fermentation
- Lecithinase positive
- Gelatinase positive
- Cultures: Aerobic
- Catalase positive
- Resistant to penicillin
- Produces a heat-labile toxin similar to enterotoxin of cholera (nausea, diarrhea, abdominal pain that lasts 12-24 hours)
- Produces a heat-stable toxin (severe nausea and vomiting with limited diarrhea)
- Vancomycin
- Vancomycin + an Aminoglycoside like Gentamicin, Neomycin or Streptomycin
bacteroides fragilis:
The Bacteroides fragilis group is a group of bacteria that resides in the human gut and in the female genital tract. It is a major cause of intra-abdominal infections such as peritonitis, intra-abdominal abscesses, and lung abscesses. These types of infections can occur as a result of a ruptured appendix, penetrating wound, or trauma. Lung abscesses usually happen as a result of aspiration pneumonia and are involved in a mixed infection (called a polymicrobial infection). Microbiologists will likely see this organism on the stools bench, steriles bench, wound bench, and blood cultures bench. If the anaerobe workups are their own bench, the anaerobes bench will work up this organism, as it is an anaerobe.
Characteristics:
Characteristics:
- Gram-negative bacilli
- Pleomorphic at times and pale-staining with rounded ends, occurring singly or in pairs, resembling "safety pins"
- Encapsulated
- Non-motile
- Anaerobe
- Catalase positive
- Bile esculin positive
- Indole negative
- Catalase positive
- Usually ferments glucose
- Small, transparent-to-opaque, glistening, convex, round, smooth colonies that are white-to-gray, entire, and convex and non hemolytic
- Metronidazole
- Clindamycin
- Ampicillin/Sulbactam
- Carbapenems
- Cefotetan
- Cefoxitin
- Piperacillin/Tazobactam
- Tacarcillin/Clavulanate
bartonella henselae:
B. henselae is a motile, Gram-negative bacillus that causes cat-scratch disease/fever following a cat scratch or bite. It causes a painless or painful enlargement of regional lymph nodes, along with a low-grade fever, malaise, fatigue, general feeling of being unwell, and sometimes a bronchitis-like illness with a dry cough that becomes chronic. It usually is self-limiting after several months without any complications. Diagnosis involves blood cultures. Blood is placed onto enriched chocolate media, incubated at 35-37 degrees Celsius with CO2 and humidity. Plates should be sealed with parafilm or shrink seals after 24 hours of incubation. Cultures can be incubated up to 30 days.
bergeyella zoohelcum:
Bergeyella zoohelcum is a Gram-negative bacilli, aerobic, non-spore-forming, nonmotile. It occasionally causes respiratory infections in Cystic Fibrosis patients. Colonies are thick, sticky, stringy, mucoid, orange-yellow, look like "snaps" because they have a raised, umbonate center surrounded by a flat, striated base.
bifidobacterium species:
Bifidobacterium species are anaerobes that are Gram-positive diphtheroids that are thin, pointed and coccoid OR large, highly irregular curved rods that branch and whose ends terminate in clubs or forked ends, making them look like "dog bones". They are non-spore-formers. On ANABAP agar, the bacterial colonies grow as small, white, convex, shiny colonies with irregular edges.It has no known specific virulence factors. It really isn't commonly found in clinical specimens and is usually only found in mixed polymicrobial infections of the abdomen or pelvis.
bilophila wadsworthii:
Bilophila wadsworthia is an anaerobic, Gram-negative, pale-staining bacillus that grows as small, translucent colonies on ANABAP agar. On BBE, it will grow after 3-5 days incubation as gray colonies with black centers due to H2S production. The colonies are susceptible to Kanamycin and Colistin, but resistant to Vancomycin. It hydrolyzes bile esculin, is indole negative, catalase positive, urease positive, nonmotile, and nonpigmented.
bordetella pertussis:
Bordetella pertussis is the causative agent for the illness known as "whooping cough". It is characterized by violent coughing, vomiting, gasping for air, and is highly communicable. The infection rate is extremely high in those who are unimmunized. In fact, it infects >90% of unimmunized people who are exposed to it! It enters the nasopharynx or mouth through aerosolized particles that attach to the respiratory cilia. This bacterium secretes many virulence factors that destroy the tissue they infect. There is immunization to protect against this bacterium. Still, there are pockets of outbreaks and epidemics that arise from time-to-time and immunization is not 100% guaranteed to prevent it. The microbiologist working on the respiratory bench will rule out this organism. Remind healthcare personnel to collect nasopharyngeal swabs containing charcoal when this disease is suspected. Other types of swabs will kill the bacteria, but charcoal will preserve them and encourage their growth during transport to the lab.
Characteristics:
Characteristics:
- Small
- Non-motile
- Obligate aerobe
- Gram-negative coccobacillus
- Oxidase positive
- Urease negative
- Nitrate negative
- DFA antibody present
- ELISA antibody present
- Use charcoal swab for nasopharyngeal culture
- Charcoal-based media enhance growth
- Erythromycin
- Azithromycin
- Clarithromycin
- Tetracycline
- Sulfamethoxazole/Trimethoprim
- Chloramphenicol
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Borrelia burgdorferi:
Borrelia burgdorferi is a spirochete bacterium. It is the causative agent of the tick-borne disease known as Lyme disease, or borreliosis. Currently, there are 52 species of Borrelia known to cause Lyme disease. It causes a typical "bull's eye target" rash on the skin. Some infections progress to Lyme arthritis, which is lifelong. Most clinical laboratories send these out to reference labs for workup and identification.
brucella melitensis:
Brucella is the causative agent of brucellosis. It is transmitted by the ingestion of contaminated products like raw dairy, raw unpasteurized milk or cheese, direct contact with an infected animal, or by the inhalation of aerosolized particles. It only takes 10-100 organisms to cause infection! There is a 2-4 week incubation period prior to the onset of symptoms. The different species of Brucella are very similar.
Characteristics:
Characteristics:
- Gram-negative
- Non-motile
- Non-spore-forming
- Facultative intracellular coccobacilli
- Round, small, glistening gray-white, shiny, convex, smooth colonies
- Malta Fever/Bang's Disease
- Undulant Fever
- Mediterranean Fever
- Rock Fever of Gibraltar
- Gastric Fever
- Undulating fever
- Night sweats
- Headache
- Arthralgia (joint pain)
- Fatigue
- Loss of appetite
- Nausea, abdominal cramps, vomiting
- Diarrhea
- Enlarged liver and spleen
- Spondylitis
- Liver abscess
- Endocarditis
- May be fatal
burkholderia cepacia:
Infections with B. cepacia are on the rise, particularly in Cystic Fibrosis patients and burn patients. This group is catalase positive, non-lactose-fermenting, Gram-negative bacilli. It most often causes pneumonia in immunocompromised patients who are already suffering from an underlying illness.
campylobacter jejuni:
Campylobacter jejune is one of the most common causes of food poisoning in the USA. Infection is referred to as campylobacteriosis. Campylobacter means "curved rod", and this is what the bacterium resembles in Gram-stain. The bacterium is found in animal feces, and it can contaminate the soil and foods such as raw milk or contaminated chicken. Eating and consuming contaminated foods results in severe gastroenteritis with stomach cramps and diarrhea, fever and malaise about 2-5 days after exposure and lasts for about a week. The diarrhea may be watery or even bloody. Ingestion of as little as 800 organisms can result in infection. A complication is that in some people, if the infection persists, it can result in chronic fatigue syndrome in a condition called Guillain-Barre' syndrome. This typically occurs about 1-2 weeks after the infection. Those working on the stools bench and the blood culture, steriles and/or anaerobes benches will work up this organism.
Characteristics:
Characteristics:
- Gram-negative, curved, helical rods that often look like "gull wings" or "S" shapes
- Microaerophilic
- Requires 5-10% CO2 (capnophilic)
- Nonfermenter
- Oxidase positive
- Reduces nitrate to nitrite
- Hippurate positive
- Single flagellum (motile)
- Optimal growth at 37-42 degrees Celsius
- Leukocytes and blood in stool
- Elevated IgA
- Erythromycin
- Azithromycin
- Ciprofloxacin
- Norfloxacin
- IV fluids often needed with electrolytes for dehydration
capnocytophaga:
Characteristics:
- Gram-negative fusiform bacilli
- Found in oropharyngeal tract of mammals and occasionally associated with bite wound infections and periodontal diseases
- Can cause dog bite infections
- Can cause sepsis
- Treated with Cephalosporins
- Needs CO2
- Gliding motility
- Anaerobes
- Pleomorphic
- Opportunistic pathogen
- Orange colonies
- Periodontal pocket or abscesses
- Can cause bacteremia, septic shock, arthritis, osteomyelitis, lung abscess, peritonitis, ovarian abscess, chorioamnionitis, conjunctivitis, endocarditis, meningitis
- Drug of choice is penicillin G
cardiobacterium hominis:
Part of the HACEK group of bacteria, Cardiobacterium hominis is a Gram-negative bacillus normally found in the mouth and upper respiratory tract of humans. It rarely causes endocarditis, which is an infection of the valves of the heart, in susceptible individuals.
Characteristics:
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citrobacter species:
Citrobacter freundii, C. koseri, are members of the Enterobacteriaceae coliform bacteria and are Gram-negative rods. They utilize citrate as a carbon (sugar) source. C. koseri is indole-positive, whereas other species of Citrobacter are indole-negative. C. koseri is also a non-lactose-fermenter, whereas C. freundii is a lactose-fermenter and also uses malonate. The bacteria is ubiquitous and can be found everywhere in the environment (soil, water, air, wastewater, etc...). It is part of the human gut as well and resides mainly in the lower intestines. Infections are opportunistic. The bacteria rarely causes infection but when it does, it causes a urinary tract infection (UTI), respiratory infection, pneumonia, infant meningitis, bacteremia or sepsis. It releases an enterotoxin and a lipopolysaccharide is present in its cell membrane, which mediates sepsis and triggers fevers, leukopenia, and disseminated intravascular coagulation (DIC) associated with meningitis and sepsis. It can be involved in polymicrobial infections. This means the organism can be seen on just about any bench, but mostly the urines bench. Inducible resistance is produced by many strains, and you may see strains that are multi-drug resistant organisms (MDROs).
Characteristics:
Characteristics:
- GNR
- Lactose-fermenter
- Motile
- Facultative anaerobe
- Ferments glucose
- Utilizes citrate
- Catalase positive
- Oxidase negative
- third generation cephalosporins
- penicillins
- imipenem
- meropenem
- fluoroquinolones
clostridium botulinum:
Clostridium botulinum is the causative agent of the deadly food poisoning known as botulism. It produces neurotoxin, which acts on the neurological system and can paralyze even the respiratory muscles, which can be fatal. The bacterium is commonly found in soil. Ingestion of preformed toxin can cause severe illness and even death. It can also cause infant botulism (contaminated formula), or wound botulism (infection of an open wound). The bacterium produces heat-resistant endospores that are able to withstand most heating methods other than sterilization by autoclaving. It is associated with contamination of foods found in bulging cans, therefore, a bulging or open can should NEVER be purchased or eaten! It is also associated with home-canned or home-jar preservation when proper steps are not followed to sterilize and seal them, enabling the bacterial spores to generate. If a jar lid is bulging, or a seal is broken, or visible bacterial growth can be seen, the products should be discarded immediately and not consumed. The bulging is evidence that the anaerobe has produced gas and the rising pressure causes the bulging can or lid. Smoked fish is also linked to transmission of botulism. The spores can actually float in the air and land on food, particularly if it is undercooked.
Ilness usually begins about 18-36 hours after exposure, and can cause blurred and double vision, drooping eyelids, nausea, vomiting, diarrhea, cramps, slurred speech, difficulty swallowing and breathing, muscle weakness, dry mouth, constipation, reduced or absent reflexes. Symptoms of infant botulism include floppy movements, constipation, facial weakness, blurred and double vision, drooping eyelids, trouble swallowing and breathing, weak cry, irritability, drooling, drooping eyelids, tiredness, difficulty sucking and feeding. Symptoms of wound botulism include the same as food borne illness.
The only treatment is immediate treatment with antitoxin. Additionally, patients must be intubated and treated with ventilation support until the respiratory muscles can resume their normal activity. Even this is no guarantee the patient will survive.
Infant botulism occurs if infants ingest food rich in C. botulinum spores, such as fresh honey. Hospitalization, supportive therapy, and ventilation support is given until the muscles can work on their own again.
Characteristics:
Ilness usually begins about 18-36 hours after exposure, and can cause blurred and double vision, drooping eyelids, nausea, vomiting, diarrhea, cramps, slurred speech, difficulty swallowing and breathing, muscle weakness, dry mouth, constipation, reduced or absent reflexes. Symptoms of infant botulism include floppy movements, constipation, facial weakness, blurred and double vision, drooping eyelids, trouble swallowing and breathing, weak cry, irritability, drooling, drooping eyelids, tiredness, difficulty sucking and feeding. Symptoms of wound botulism include the same as food borne illness.
The only treatment is immediate treatment with antitoxin. Additionally, patients must be intubated and treated with ventilation support until the respiratory muscles can resume their normal activity. Even this is no guarantee the patient will survive.
Infant botulism occurs if infants ingest food rich in C. botulinum spores, such as fresh honey. Hospitalization, supportive therapy, and ventilation support is given until the muscles can work on their own again.
Characteristics:
- Thick, spore-forming, Gram-positive bacilli
- Look like safety pins or sewing needles
- Lecithinase positive
- Motile
- Obligate Anaerobe
- Produces lethal neurotoxin (blocks the release of acetylcholine from the presynaptic nerve terminals in the autonomic nervous system as well as the motor endplates, which leads to flaccid muscle paralysis)
clostridium difficile: pseudomembranous enterocolitis
C. difficile bacteria are Gram-positive, straight rods that may chain. Spores are oval and subterminal. On ANABAP, colonies are large, white, circular, matte-to-glossy, convex, opaque, resemble "ground glass", and are non hemolytic. Colonies produce a foul odor characteristic of a horse stable. They fluoresce yellow-green under UV light.
This bacterium is the pathogen responsible for antibiotic-associated pseudomembranous enterocolitis (diarrhea). This typically follows antibiotic therapy with a broad spectrum antibiotic like ampicillin, clindamycin, or one of the cephalosporins, which knock out much of the normal intestinal microflora. This leaves room for the overgrowth of yeast and C. difficile, which are normally kept in check by the microflora. This is why it is great to supplement your diet with lots of yogurt, kefir, buttermilk, products containing live bacterial cultures to replenish your normal microflora after antibiotic therapy.
Sometimes C. difficile causes such a major overgrowth that it results in a superinfection of the colon, where it releases exotoxins (Toxin A and Toxin B). Toxin A causes diarrhea. Toxin B kills the colon cells. This results in severe, watery, explosive, putrid diarrhea, abdominal cramps, and fever. The colon becomes inflamed, red, and produces pus and a white exudate called a pseudomembrane on the large intestine, which can be seen by colonoscopy. The mucosal surface under the pseudomembrane become necrotic and sloughs off, so pus and mucous may be seen in the diarrhea. Stool tests for Toxin A and Toxin B confirm the diagnosis, and treatment means that the initial antibiotic therapy is halted. Instead, metronidazole or vancomycin are given instead.
Characteristics:
This bacterium is the pathogen responsible for antibiotic-associated pseudomembranous enterocolitis (diarrhea). This typically follows antibiotic therapy with a broad spectrum antibiotic like ampicillin, clindamycin, or one of the cephalosporins, which knock out much of the normal intestinal microflora. This leaves room for the overgrowth of yeast and C. difficile, which are normally kept in check by the microflora. This is why it is great to supplement your diet with lots of yogurt, kefir, buttermilk, products containing live bacterial cultures to replenish your normal microflora after antibiotic therapy.
Sometimes C. difficile causes such a major overgrowth that it results in a superinfection of the colon, where it releases exotoxins (Toxin A and Toxin B). Toxin A causes diarrhea. Toxin B kills the colon cells. This results in severe, watery, explosive, putrid diarrhea, abdominal cramps, and fever. The colon becomes inflamed, red, and produces pus and a white exudate called a pseudomembrane on the large intestine, which can be seen by colonoscopy. The mucosal surface under the pseudomembrane become necrotic and sloughs off, so pus and mucous may be seen in the diarrhea. Stool tests for Toxin A and Toxin B confirm the diagnosis, and treatment means that the initial antibiotic therapy is halted. Instead, metronidazole or vancomycin are given instead.
Characteristics:
- Gram-positive bacilli
- Endospore-forming
- Motile
- Anaerobe
- Positive C. difficile toxin assay or PCR
- Fecal leukocytes are positive
- Metronidazole
- Vancomycin
clostridium perfringens:
C. perfringens is a causative agent of both food poisoning and wound infections. Wound infections are serious, as they can cause necrosis, bacteremia, and gas gangrene, and limb amputation may become necessary in order to preserve life. The bacterial spores can be found in the soil, in anaerobic conditions, and it can produce gas. The spores can contaminate wounds from trauma or war. Deep wounds produce necrotic tissue. This creates the perfect environment (anaerobic) for spores to germinate into active bacteria, which then releases the potent exotoxins, which continue to damage the tissue. Wound infections damage local tissue, leading to cellulitis and a moist spongy, crackling consistency of the skin because of pockets of gas. This is referred to crepitus. Deeper infections give rise to myonecrosis, which results in muscle destruction and death. Pockets of gas become trapped in the muscle tissue in addition to the subcutaneous tissue. Potent enzymes destroy the muscle and cause a black, thin fluid to exude from the skin (gas gangrene). This is lethal and fatal without treatment early on, which may include amputation, hyperbaric oxygen therapy, heavy antibiotic therapy, and being monitored very closely for spread of infection.
C. perfringens exhibits double zones of beta hemolysis on blood agar. Colonies are gray to gray-yellow, circular, shiny, glossy, dome-shaped, entire, translucent on ANABAP agar.
Characteristics:
C. perfringens exhibits double zones of beta hemolysis on blood agar. Colonies are gray to gray-yellow, circular, shiny, glossy, dome-shaped, entire, translucent on ANABAP agar.
Characteristics:
- Large, boxcar-shaped, thick, Gram-positive rods with blunt ends (singles or pairs)
- Endospore-forming (large endospores either central or subterminal and oval in shape)
- Rarely seen in stained preparations
- Look like sewing needles
- Anaerobes
- Nonmotile
- Divide in THIO broth in just 6.3 minutes!
- Penicillin G
- Metronidazole
- Clindamycin
- Carbapenem
clostridium septicum:
This bacterium can cause gas gangrene, and it is associated with colorectal cancer and problems with the bowel. It has also been known to cause infections in burn and trauma patients, post-surgical infections, diabetic infections, infections in those with peripheral vascular disease, infections of the skin, and septic abortions. It causes myonecrosis, muscle tissue damage.
On ANABAP agar, colonies appear as gray, circular, glossy, translucent, irregular with rhizoid-like margins looking like a "Medusa head", are beta-hemolytic, and swarm the entire agar rapidly, often in <24 hours.
Characteristics:
On ANABAP agar, colonies appear as gray, circular, glossy, translucent, irregular with rhizoid-like margins looking like a "Medusa head", are beta-hemolytic, and swarm the entire agar rapidly, often in <24 hours.
Characteristics:
- Thick Gram-positive bacilli but become Gram-negative with age or stain unevenly; rods are straight or curved, occurring singly or in pairs
- Spore-forming (subterminal, oval)
- Obligate anaerobe
- Motile
- Beta-lactam drugs
- Penicillin
- Cephalosporins
clostridium tertium:
Characteristics:
- Gram-positive or variable rods
- Endospore-forming (terminal)
- Motile
- Anaerobe
- Can cause necrotizing fasciitis and gangrene
- Can cause bacteremia and sepsis
- Can cause meningitis
- Can cause septic arthritis
- Can cause enterocolitis
- Can cause peritonitis
- Can cause brain abscess
- Can cause pneumonia
- Can cause osteomyelitis
- Can cause soft tissue infections
- Patients who get an infection typically have neutropenia
- Vancomycin
- Trimethroprim/Sulfa
- Ciprofloxacin
clostridium tetani:
C. tetani is the causative agent of tetanus due to the production of tetanospasm and tenolysin, 2 potent exotoxins. Infection typically follows a puncture wound with a rusty nail. Tetanus causes painful muscular spasms (tetany), "lock-jaw", and respiratory failure. It can be fatal. This is why immunization and periodic booster shots are given every 10 years or so. Incubation period is anywhere from 3-21 days, and illness lasts about 2 weeks. The bacterium is found in the soil and also in the GI tract of animals and is heavy where manure-coated soils are found. The endospores are very hardy and resistant to most antiseptics and heating methods. On ANABAP, the colonies grow as gray, matte, irregular-to-rhizoid, translucent, flat, with a narrow zone of beta-hemolysis that may swarm the agar. Treatment includes immunization, immune globulins to neutralize the toxin, cleansing of the wound, antibiotics (penicillin), and intensive supportive therapy, including muscle relaxants. Sometimes ventilation is needed as well because tetanus can cause respiratory failure with constant muscle contraction since the inhibitory signals are blocked.
Characteristics:
Characteristics:
- Club-shaped, Tennis-racket, Drumstick-shaped rods
- Spores that are oval and terminal or subterminal
- Gram-positive bacilli, becoming Gram-negative with age (>24 hours), which occur singly and in pairs
- Anaerobe
- Motile
- Tetanus immune globulin
- Metronidazole
- Penicillin G
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corynebacterium diphtheriae:
C. diphtheriae is the causative agent of diphtheria. With immunization, we rarely see this illness anymore, which used to be quite fatal in the past. The disease causes pharyngitis with formation of a pseudomembrane in the back of the throat. It causes the neck to swell, with extreme inflammation, making it difficult to swallow and breathe. Symptoms include sore throat, fever, and a gray or white thick patch in the back of the throat. It can block the airway, causing croup. There is also a form that can cause skin infections as well. Myocarditis of the heart is a complication that may occur. Other complications include inflammation of the kidneys, nerve inflammation, bleeding, and low platelet count.
Characteristics:
Characteristics:
- Nonmotile
- Nonspore-forming
- Gram-positive diphtheroid rod that looks like "clubs", "V-shapes", "Chinese Letters", or "drumsticks", often in palisade formation (side-by-side)
- Glucose fermenter
- Maltose fermenter
- Urease negative
- Penicillin G
- Erythromycin
corynebacterium haemolyticum:
This is the same thing as Arcanobacterium haemolyticum.
corynebacterium urealyticum:
C. urealyticum is an important isolate in conjunction with a urinary tract infection (UTI). The urease enzyme secreted by the bacterium causes the urine to become alkaline. It is associated with the formation of kidney stones or renal stones (struvite calculi). Patients who are already immunosuppressed, are on strong or long-term broad spectrum antibiotic therapy, or those with an underlying genitourinary disorder are at risk for infection with this organism.
cronobacter:
Cronobacter is an opportunistic pathogen, Gram-negative bacilli, oxidase negative, catalase positive, that lives in dry places. It has been associated with infections of all age groups, including low birth weight premature infants, older infants, and adults. It causes invasive infections with high mortality rates ranging from 40-80% because these infections are severe and include things like bacteremia, sepsis, meningitis, and necrotizing enterocolitis. Contaminated infant formula has been associated with these infections and high mortality rate. The bacterium is so hardy that it is able to withstand harsh, dry conditions and survive a desiccated (dried out) state for years at a time. The bacterium has contaminated tampons and vegetables as well.
eikenella corrodens:
Eikenella corrodens is part of the commensal flora of the human oral cavity, however, it has been associated with opportunistic infections, including skin abscesses and bite wound infections, pulmonary empyema, brain abscesses, endocarditis, meningitis, and osteomyelitis. After 48 hours incubation, it produces flat, discoid colonies with irregular margins that look like dried condensation fluid, and are usually surrounded by a faint zone of greenish discoloration. Colonies have a strong bleach-like odor.
Characteristics:
Characteristics:
- Fastidious Gram-negative bacilli (short rods, may not stain completely in the middle)
- Facultative anaerobe (slow-growing)
- "Pit" the agar
- Smell like "bleach" and are malodorous
- Tiny pinpoint, dry, hazy, gray colonies that tend to "stick" to the agar
- Greenish discoloration underneath the colonies
- Oxidase positive
- Catalase negative
- Urease negative
- Indole negative
- Reduces nitrate to nitrite
- Needs 3-10% CO2
- Found in the human mouth and upper respiratory tract flora
- Can cause bite wound infections, respiratory infections (especially in patients with CF), infections associated with cancers of the head and neck, diabetics are prone to infection, IV drug users are prone to infection
- Part of the HACEK group of bacteria (culture-negative endocarditis and 3% of all cases of infective endocarditis in those with poor oral hygiene or periodontal disease)
- Treatment consists of the Penicillins, Cephalosporins or Tetracyclines
elizabethkingia meningoseptica:
Characteristics:
- Gram-negative bacilli, slightly curved
- Ubiquitous
- May be carried by and cause infection in Cystic Fibrosis patients
- Associated with meningitis in kids
- Nonmotile
- Non-spore-forming
- Aerobic
- Catalase positive
- Indole positive
- Oxidase positive
- Urease negative
- PYR positive
- Nitrate reduction negative (a few are positive)
- Good growth on blood and chocolate agars but not on MacConkey agar
- Glucose oxidizer
- Pale yellow colonies surrounded by gray discoloration
- Don't grow on CNA agar
- Susceptible to quinolones
- Colistin-resistant but vancomycin-susceptible
- Occasionally causes infections from contaminated venous lines, contaminated water or dialysate or other fluids, nosocomial pneumonia, endocarditis, post-surgical infections, bacteremia, meningitis in immunocompromised adults, soft tissue sepsis, necrotizing fasciitis
enterobacteriaceae:
Enterobacteria are residents of the human gastrointestinal tract, and are referred to as coliforms. They only cause opportunistic infections if they are in the right place at the right time. The most common infections they cause are urinary tract infections (UTI), but you will also see them on just about every bench as causative agents of infection or on the stool bench as normal flora. The most common ones you will see include:
Characteristics:
- Citrobacter species
- Cronobacter species
- Edwardsiella species
- Enterobacter species
- Erwinia species
- Escherichia coli
- Ewingella species
- Hafnia species
- Klebsiella species
- Morganella species
- Pantoea species
- Plesiomonas species
- Proteus species
- Providencia species
- Pseudomonas species
- Rauoltella species
- Salmonella species
- Serratia species
- Shigella species
- Yersinia enterocolitica
- Looking for the ability, or inability, to ferment lactose and convert it into gas (represented by cracks or bubbles) an acid (usually a color change by a color indicator)
- Production of H2S gas (represented by a black pigment)
- Ability to hydrolyze urea (represented by a color change to bright fuchsia)
- Motility testing to determine whether or not they are motile or non-motile
- Testing to determine whether the bacteria possesses the ability to alkalinize or acidify the agar
- Water testing (millipore) for contamination
Characteristics:
- Gram-negative rods
- Oxidase negative
- Facultative anaerobes
- Produce acid from glucose fermentation
- Referred to as "coliform"
- Part of the normal flora of the human gut (GI tract/intestines)
enterobacter species:
E. aerogenes, and E. cloacae are two of the significant species of Enterobacter species. E. cloacae B29 strain may be implicated in the gut of those who are obese. It may mediate inflammation. These species are associated with nosocomial (hospital-acquired) infections.
Characteristics:
Characteristics:
- Gram-negative bacilli
- Facultative anaerobes
- Can cause opportunistic urinary and respiratory tract infections
- Lactose-fermenters (some late)
- Gas production
- Oxidase negative
- Indole negative
- Urease variable
- Some strains are MDRO
- Highly motile
enterococcus species:
Enterococcus species of bacteria are Gram-positive cocci in pairs and chains. They are facultative anaerobes. They survive harsh conditions and environments, but they are non-spore-formers. They exhibit alpha or gamma-hemolysis on blood agar. They are associated with quite a few nosocomial infections. Many strains are highly antibiotic-resistant and have the ability to form biofilms, which make infections difficult to treat and eradicate.
- E. faecalis
- Part of the Group D Streptococcus family (see Streptococcus Group D below)
- Gram-positive cocci in pairs and chains
- Part of the human commensal flora of the GI tract
- Can cause life-threatening nosocomial infections
- Many strains are highly antibiotic-resistant
- Also causes dental infections in root canals or that are associated with the need for one
- Nonmotile
- Ferments glucose
- Weakly catalase positive or catalase negative
- Can hydrolyze bile esculin
- Able to form biofilms
- Infections include infectious endocarditis, UTI, septicemia, meningitis, respiratory, ear, catheter-associated
- E. faecium
- Gram-positive cocci
- Alpha or gamma-hemolytic on blood agar
- Commensal flora of the human GI tract that is occasionally associated with infective endocarditis, meningitis,bloodstream, bacteremia, sepsis, wound, surgical, catheter-associated or UTI
- Vancomycin-resistant strains are common and are called VRE
- MDRO
- Creates biofilms on catheters, ventilator tubing, central lines, urinary catheters, etc...
- E. gallinarum
- Gram-positive cocci
- Inherent resistance to vancomycin
- Known to cause outbreaks and spread in hospitals (nosocomial infections)
- E. casseliflavus
- E. raffinosjus
escherichia coli:
E. coli is a member of the Enterobacteriaceae that inhabits the human GI tract and that of many animals. There are a variety of different strains. Most of the time, E. coli infections are opportunistic infections due to the bacterium being in the right place at the right time under the right conditions, and may range from mild upset stomach to a UTI to something serious like sepsis or meningitis. Strains carried in cows and ingestion of contaminated undercooked beef can make us sick. They are named according to their virulence factors and properties. They include the following:
- Enteropathogenic E. coli (EPEC): diarrhea in infants
- Enterotoxigenic E. coli (ETEC): infant diarrhea or traveler's diarrhea (any age)
- Enterohemorrhagic E. coli (EHEC): causes hemorrhagic (bloody) colitis (diarrhea), or hemolytic uremic syndrome (HUS)
- E. coli O157:H7: responsible for outbreaks of hemorrhagic colitis in the USA
- Enteroinvasive E. coli (EIEC): causes a shigellosis-like illness with bloody diarrhea and cramping
- Engeroaggregative E. coli (EAEC): causes acute and chronic diarrhea
- Gram-negative rods
- Facultative anaerobe
- Part of the normal flora of humans
- Fermenting and non-fermenting strains (lactose)
- Flat and mucoid strains
- Most strains are harmless
- There are serotypes associated with food poisoning ("Traveler's Diarrhea") (O157:H7)
- They produce vitamin K2, which is needing for blood clotting and wound healing
- Many are motile (produce flagella) (peritrichous)
- Infections can include gastroenteritis, UTI (most common cause), respiratory, neonatal meningitis, hemorrhagic colitis, Crohn's disease, mastitis, sepsis)
- Cephalosporins
- Ampicillin
- Sulfamethoxazole
eubacterium:
Eubacterium is a member of the Eubacteriaceae, and it is a Gram-positive bacilli with a thick, rigid cell well. Some strains are motile, whereas other strains are nonmotile. This bacterium is associated with bacterial vaginosis in females. Bacterial vaginosis, or BV, is characterized by an overgrowth of certain bacteria and lack of the normal protective commensal Lactobacillus species. Symptoms include an increased vaginal discharge, sometimes itching, burning, discomfort, and even pain and burning upon urination. Sometimes there are no symptoms at all. It is usually caused by an imbalance of flora and the normal pH of the urogenital tract.
fusobacterium species:
Fusobacterium species are fusiform, Gram-negative rods, anaerobic, non-spore-forming, slender with pointed ends. These are opportunistic pathogens that normally reside in the human mouth, urinary, upper respiratory and gastrointestinal tracts. When they do cause infection, it is usually a polymicrobial infection. They can cause periodontal disease, Lemierre's syndrome (shock and sepsis following a bacterial sore throat infection), peritonsillar abscess, infectious thrombophlebitis of the jugular vein, sinusitis, aspiration pneumonia, lung abscesses, brain abscesses, systemic infections, and skin ulcers. Researchers discovered recently, in 2011, that the bacterium thrives in colon cancer cells. It has also been linked to ulcerative colitis. It is also an anchor for bacterial biofilms. They are virulent because they release potent endotoxins that can lead to toxic shock and systemic collapse. Treatment usually consists of Clindamycin. Species of clinical significance include:
- F. mortiferum
- Gram-negative, pale-staining, irregular-stained, highly pleomorphic rods with swollen areas, filaments, large, bizarre, round bodies
- Grows on ANABAP agar as circular, entire or having irregular edges, convex, barely umbonate, smooth, translucent, non hemolytic colonies
- Gram-negative, pale-staining, irregular-stained, highly pleomorphic rods with swollen areas, filaments, large, bizarre, round bodies
- F. necophorum
- Gram-negative, pleomorphic bacilli, round-to-tapered ends, filamentous or round bodies, more pleomorphic with age
- On ANABAP agar, grows as circular, umbonate colonies with a ridged surface, translucent or opaque, will fluoresce chartreuse under UV light, the agar will green upon exposure to air, some strains are beta-hemolytic
- F. nucleatum
- Gram-negative, pale-staining, long, slender, spindle-shaped rods with sharp pointed edges or tapered ends
- On ANABAP agar, grows as either bread crumb-like, white or gray-white colonies, speckled, or smooth; also greens the agar upon exposure to air and also fluoresces chartreuse under UV light, but usually non hemolytic
- F. varium
- Gram-negative, uneven staining, pleomorphic, short oval rods occurring as singles or pairs
- On ANABAP, grows as colonies with gray-white centers with colorless edges that look like fried eggs and are circular, entire, convex, translucent, and nonhemolytic
- Pleomorphic GNR
- Nonmotile
- Anaerobes
- Nonspore-forming
- Spindle-shaped
- Indole positive
- Catalase negative
- Bile esculin negative
- Do not ferment mannitol, lactose, or rhamnose
- Some are beta-lactamase positive
- Cefoxitin
- Imipenem
gardnerella vaginalis:
Gardnerella vaginalis is a species of Gram-negative, variable staining, pleomorphic facultative anaerobic, non spore forming coccobacilli. On blood agar, it grows as small, glistening, water-like, transparent, translucent, round, convex colonies. Together with other, mostly anaerobic bacteria, it causes bacterial vaginosis in females due to the disruption of the normal commensal flora and vaginal pH. The resident nonpathogen that fights for nutrients and keeps the urogenital tract healthy is called Lactobacillus. Absence or lack of this organism in Gram-stained specimens is a key evidence for this disruption. Carriers may be asymptomatic. Those that do have symptoms experience a foul vaginal discharge, vaginal irritation or itching, and a "fish-like" odor. Classic "clue cells" will be seen in the Gram-stain under the microscope, showing the bacteria adhering to at least 75% of the epithelial cells, and at least 25% of the slide will contain clue cells. There will also be an absence or lack of Lactobacillus, which are long, Gram-positive bacilli that keep the urogenital tract healthy.
haemophilus aphrophilus and parainfluenzae:
H. aphrophilus and H. parainfluenzae are part of the HACEK group of bacteria, fastidious Gram-negative coccobacilli associated with infectious endocarditis, among other types of infections. They are opportunistic pathogens. They also cause ear infections, bronchitis, conjunctivitis, pneumonia, abscesses, and genital tract infections. Two other strains, H. parahaemolyticus and H. haemolyticus, have also rarely caused infections.
haemophilus influenzae:
As a microbiologist, you will mainly be looking for this organism on the respiratory bench. The commensal strains are found in the nasopharynx of humans. Virulent strains also exist here, but are rarer. It requires factors V and X to live.
Characteristics:
Characteristics:
- Gram-negative coccobacillus (small)
- Nonmotile
- Good growth on Chocolate Agar and Haemophilus Quad Plate with X and V Factors
- Facultative Anaerobe
- Blood agar growth is only shown as satellite growth around other bacteria such as S. aureus (tiny smooth, transparent, translucent or grey convex colonies)
- Incubate in 37 degrees C in a CO2 incubator
- Catalase positive
- Oxidase positive
- Encapsulated (a, b, c, d, e, f) and unencapsulated strains
- Hib substrain can cause epiglottitis, pneumonia, bacteremia, and acute bacterial meningitis and there is a vaccination for this subtype
- This is the most common cause of bacterial meningitis in unvaccinated children
- Some strains cause cellulitis, osteomyelitis, and infectious arthritis
- Some strains cause neonatal infection
- Can cause lower respiratory infections
- Hib substrain can cause epiglottitis, pneumonia, bacteremia, and acute bacterial meningitis and there is a vaccination for this subtype
- Unencapsulated strains can cause:
- Eye infections
- Ear infections
- Sinusitis
- Pneumonia
- Endocarditis
- Upper respiratory infection with fever leading to wheezing and bronchitis
- Causes a bacterial respiratory infection
- Causes ear infections
- Can cause meningitis
- Second or third generation cephalosporins
- Chloramphenicol
- Fluoroquinolones
- Ampicillin
- Amoxicillin
- Cefactor
- Sulfa/Trimethoprim
hafnia:
Characteristics:
- Gram-negative bacilli
- Facultative anaerobe
- Often an MDRO
- Part of the commensal flora of the human GI tract, but can occasionally cause infection in the immunocompromised or can cause a UTI
helicobacter pylori:
Helicobacter pylori is a corkscrew-shaped bacterium that bores itself into the gastric mucosa and is the most common cause of duodenal ulcers. It also causes chronic gastritis and gastric ulcers along with dyspepsia (belching and heartburn). The worry is that it is linked to gastric cancer/carcinoma. It is responsible for inflammation because it blocks gastric acid production with inhibitory proteins and it also neutralizes the acid with ammonia by hydrolyzing urea. It sneaks past the immune system and hides from it by producing a couple of enzymes: superoxide dismutase and catalase. The immune response to the organism is potent, causing many of the symptoms experienced by the host.
Treatment includes Pepto-Bismol, which contains bismuth salts to inhibit the growth of this bacterium. Antacids to reduce stomach acid and inflammation are also helpful. Antibiotics aid in treating the duodenal and gastric ulcers to clear the bacterium.
Characteristics:
Treatment includes Pepto-Bismol, which contains bismuth salts to inhibit the growth of this bacterium. Antacids to reduce stomach acid and inflammation are also helpful. Antibiotics aid in treating the duodenal and gastric ulcers to clear the bacterium.
Characteristics:
- Motile
- Curved, spiral, corkscrew or straight, slightly plum Gram-negative rods
- Rapidly urease positive
- Catalase positive
- Oxidase positive
- Tests include rapid urease (Clotest), culture, direct antigen test, serology testing, urea breath test and confirmation by gastric biopsy
- Amoxicillin
- Tetracycline
- Metronidazole
- Bismuth subsalicylate (Pepto-Bismol)
kingella kingae:
Kingella kingae is part of the HACEK group of bacteria. It is Gram-negative, coccobacilli, associated with septic arthritis, osteomyelitis, spondylodiscitis, bacteremia, meningitis, lower respiratory infection, and endocarditis.
Characteristics:
Characteristics:
- GNCB
- Oxidase positive
- Catalase negative
- Beta-hemolytic
- Some strains produce beta-lactamase
klebsiella species:
Klebsiella species are part of the Enterobacteriaceae. These bacteria are ubiquitous, being found in soil, water, grain, fruits, vegetables, and the GI tracts of humans and many animals. It is carried in the nasopharynx and oropharynx of humans as well. Sometimes it is transmitted via aerosol droplets from one person to another. It is a very common nosocomial pathogen and also causes community-acquired pneumonia, UTI, bronchitis, surgical wound infections, biliary tract infections, and bacteremia. It produces a potent endotoxin and a slimy capsule that enables it to evade the immune system response. Many strains have also become multi-drug-resistant.
Characteristics:
Characteristics:
- Gram-negative bacilli (short, thick rods)
- Nonmotile
- Oxidase negative
- Indole negative
- Mucoid
- Presence of a capsule
- Found everywhere in nature (ubiquitous)
- Facultative anaerobes
- Grow at 35-37 degrees Celsius with a pH of 7.2
- Can cause UTIs, pneumonia, septicemia, meningitis, diarrhea, soft tissue and wound infections, medical device biofilm and infection
- Cephalosporins
- Penicillins
- Imipenem
- Aztreonam
- Meropenem
- Fluoroquinolones
klebsiella oxytoca:
klebsiella pneumoniae:
K. pneumoniae is the most common cause of nosocomial respiratory tract infections. It is also one of the most common causes of premature intensive care infections. It is the second most common cause of Gram-negative bacteremia, sepsis and urinary tract infections (second to E. coli). Some strains are MDRO. Cystic fibrosis patients tend to become reinfected with this organism over and over again as a cause of respiratory infection and pneumonia. This bacteria has gained the ability to colonize the hospital environment, including implantable devices, orthotics, carpeting, sinks, surfaces, even flowers, and the skin of healthcare personnel and patients. The organism contains a slime capsule, which makes it very mucoid and slimy. It is nonmotile, but has the ability to glide across the surface of the agar since it is encapsulated and possesses O antigen. it causes urinary tract infections in hospitalized patients who have indwelling Foley catheters. The horrible pneumonia caused by this organism destroys lung tissue, resulting in bloody sputum and lung cavitation, making it look like "red currant jelly". Infection has a high mortality rate, even with antibiotic therapy.
legionella pneumophila:
Legionella pneumophila is not a part of the human commensal flora. This organism was discovered in 1976 following an outbreak of Legionnaires' disease at a hotel where a convention was taking place. Some 200 people died, but the disease was not spread from person-to-person. Through much research, it was discovered that the outbreak had occurred via the ventilation system of the hotel, and is spread via aerosolized droplets from environmental sources. The bacterium has been isolated from fresh water sources, plumbing, heating and air conditioning vents, misters, and aquatic habitats across the world. It has even been isolated from chlorinated hot tubs! This shows how it survives harsh conditions. It is a parasite of amoebae that live in water. For this reason, it is classified as an intracellular pathogen. In humans, it survives and multiplies inside of human immune cells called macrophages.
Illness caused by the organism is referred to as legionellosis, which includes Legionnaires' disease (pneumonia-like illness), Pontiac fever (milder, flu-like illness) and other respiratory illnesses. There are approximately 1500-2000 cases per year in the USA.
Characteristics:
Illness caused by the organism is referred to as legionellosis, which includes Legionnaires' disease (pneumonia-like illness), Pontiac fever (milder, flu-like illness) and other respiratory illnesses. There are approximately 1500-2000 cases per year in the USA.
Characteristics:
- Gram-negative bacilli
- Motile
- Non-spore-forming
- Aerobic
- Causative agent of Legionellosis
- Causative agent of the pneumonia-like illness known as Legionnaire's Disease
- Causative agent of the mild flu-like illness known as Pontiac Fever
- Growth on Buffered Charcoal Yeast Extract Agar (BCYE)
- Common in soil and aquatic systems and spread through the air vents
- May be identified using a Legionella Urinary Antigen Test, culture, DNA probe, or PCR
- Azithromycin
- Rifampin
- Erythromycin
- Clarithromycin
- Ciprofloxacin
- Levofloxacin
leuconostoc, pediococcus, and other similar species:
Leuconostoc spp and Pediococcus spp are organisms that are typically only able to cause opportunistic infections in those who are severely immunocompromised and have impaired immune systems. These bacteria are typically found on foods, vegetables, and dairy products. They are Gram-positive cocci and of low virulence. These two species are inherently resistant to vancomycin, which may play a part in their ability to cause rare nosocomial infections. When encountered, they should be considered as probable contaminants unless cultures are pure or unless they are found in multiple blood culture bottles. Pediococcus species are large, spherical cocci arranged in tetrads, pairs or singles. Leuconostoc species may elongate and appear as coccobacilli, pairs or chains. Both are alpha or gamma-hemolytic on blood agar. Both are catalase negative.
Other similar Gram-positive cocci that are usually contaminants but may be linked to rare opportunistic infections in the immunocompromised include:
Other similar Gram-positive cocci that are usually contaminants but may be linked to rare opportunistic infections in the immunocompromised include:
- Lactococcus spp
- Coccobacilli or chains
- Alpha or non-hemolytic
- Coccobacilli or chains
- Globicatella spp
- Cocci, Chains, Pairs
- Alpha-hemolytic
- PYR +
- Aerococcus spp
- Large, spherical cocci arranged in tetrads, pairs or singles or clusters
- Alpha-hemolytic
- Gemella spp (normal flora of the human oral and upper respiratory tracts)
- Large, spherical cocci arranged in tetrads, pairs or singles, clusters
- Alpha or non-hemolytic
- PYR +
- Helcococcus sp
- Cocci in singles pairs, chains or clusters
- Non-hemolytic
- BE+
listeria monocytogenes:
Listeria monocytogenes is a Gram-positive, non-spore-forming bacillus that has a prevalence for nervous tissue. It is commonly found in the soil and on fruit and vegetables, and it decomposes them. It can also be found in red meat, lunch meat, hot dogs, poultry, fish, and the GI tract of humans and animals. It also commonly contaminates raw milk and cheese. Therefore, it is considered to be a food borne contaminant. It is either ingested or enters through openings in the skin, where it spreads by hitching a ride in immune cells.
The bacterium has a prevalence for pregnant women and fetuses, the immunocompromised, and the elderly. In fact, it is a common cause of meningitis in neonates, who contract listeriosis from their asymptomatic carrier mothers during childbirth and delivery. It is the third most common cause of neonatal meningitis after Group B Strep (GBS) and E. coli. It also causes listeriosis and risk for meningitis in the immunosuppressed and the mortality rate is very high. In healthy individuals, listeriosis can cause gastroenteritis.
It is able to evade the immune system and survive harsh conditions and survive inside or outside of cells. It is referred to as a facultative intracellular microbe. CSF is the specimen collected via lumbar puncture and stained by Gram-stain and cultured to look for evidence of bacterial meningitis. Neutrophilia, high protein levels, low glucose, and a Gram-stain showing Gram-positive bacilli are suspicious for this organism. Treatment of choice is ampicillin or trimethoprim-sulfamethoxazole.
Characteristics:
The bacterium has a prevalence for pregnant women and fetuses, the immunocompromised, and the elderly. In fact, it is a common cause of meningitis in neonates, who contract listeriosis from their asymptomatic carrier mothers during childbirth and delivery. It is the third most common cause of neonatal meningitis after Group B Strep (GBS) and E. coli. It also causes listeriosis and risk for meningitis in the immunosuppressed and the mortality rate is very high. In healthy individuals, listeriosis can cause gastroenteritis.
It is able to evade the immune system and survive harsh conditions and survive inside or outside of cells. It is referred to as a facultative intracellular microbe. CSF is the specimen collected via lumbar puncture and stained by Gram-stain and cultured to look for evidence of bacterial meningitis. Neutrophilia, high protein levels, low glucose, and a Gram-stain showing Gram-positive bacilli are suspicious for this organism. Treatment of choice is ampicillin or trimethoprim-sulfamethoxazole.
Characteristics:
- Gram-positive bacilli, showing pallisades formation
- Causative agent of Listeriosis
- Facultative anaerobe
- Foodborne pathogen
- May cause fatal infections
- Motile at 30 degrees C and below
- Nonmotile at 37 degrees C
- Umbrella motility
- Can cause meningitis in newborns
- Catalase positive
- Oxidase negative
- Beta-hemolytic on blood agar
- Tumbling motility
- Bile esculin positive
- Ferments glucose, trehalose, and salicin
- Releases endotoxin
- Ampicillin
- Gentimicin
- Penicillin G
mobiluncus species:
Mobiluncus species are Gram-variable, small, thin, curved bacilli that produce tiny colonies on ANABAP agar after 48 hours incubation. After 3-5 days incubation, colonies appear small, low convex, and translucent.
When looking at Gram-stained slides to rule out bacterial vaginosis, this organism will appear as curved Gram-negative, pleomorphic bacilli with variable staining patterns, they will cover the surface and edges of the epithelial cells (75%) to form "clue cells", at least 25% of the epithelial cells in the slide will have this appearance, and there will be a lack or absence of Lactobacillus.
When looking at Gram-stained slides to rule out bacterial vaginosis, this organism will appear as curved Gram-negative, pleomorphic bacilli with variable staining patterns, they will cover the surface and edges of the epithelial cells (75%) to form "clue cells", at least 25% of the epithelial cells in the slide will have this appearance, and there will be a lack or absence of Lactobacillus.
moraxella (branhamella) catarrhalis:
M. catarrhalis is an organism that is part of the normal commensal microflora of the nasopharynx. It can cause otitis media (middle ear infection), sinusitis, bronchitis, and pneumonia. Colonies are small, circular, slightly raised, gray-white to dirty-white on blood and CHOC agar. In broth, cultures are turbid with a slight pellicle. This bacterium does not ferment any of the carbohydrates. In saline solution, there is a tendency for it to auto-agglutinate (clump).
Characteristics:
Characteristics:
- Gram-negative coccobacilli (large) or diplococci or singles, tetrads or clumps, usually in "coffee bean" pair formation
- Strict aerobe
- Oxidase positive
- Catalase positive
- Can cause lower respiratory infection and pneumonia
- Can cause middle ear infections
- Can cause eye infections
- Can cause tracheobronchitis
- Can cause sinusitis
- Very rarely causes bacteremia or meningitis
- M. lacunata causes blepharoconjunctivitis in humans
morganella morganii:
Characteristics:
- Part of the normal fecal flora
- Gram-negative bacilli
- Can cause nosocomial infections, post-surgical, UTI infections, wound infection, post-surgical infection, peritonitis, CNS infection, endolphthalmitis, pneumonia, chorioamnionitis, neonatal sepsis, pyomyosititis, arthritis, necrotizing fasciitis
- Facultative anaerobe
- Oxidase negative
- Off-white, opaque, medium colonies, smooth, convex, pinpoint white centers, shiny
- Motile but some nonmotile at 30 degrees C
- Indole positive
- Catalase positive
- Methyl red positive
- Some strains are MDROs
Mycobacterium (see tab devoted to mycobacterium for all the species)
neisseria gonorrhoeae:
N. gonhorrhoeae (gonococcus) is the causative agent of the STD gonorrhoea. It is the second most commonly transmitted STD after chlamydia. In males, this causes an infection known as "the clap", in which the urethra become inflamed (urethritis), causing painful urination along with a purulent discharge involving pus that can be expressed from the tip of the penis. Men can pass this to women during sexual intercourse, regardless of whether or not they are experiencing any symptoms, because some are simply asymptomatic carriers. Complications in males include epididymitis, prostatitis, or urethral strictures (narrowing of the urethra due to inflammation and scar tissue). It is cured with the antibiotic ceftriaxone. In females, the urethra also becomes inflamed (urethritis), resulting in painful, burning urination and a purulent discharge (less than that of males). It infects the cervix, causing it to become red and friable (bleed easily) with a purulent exudate. Many women are also asymptomatic, but can pass the bacterium to men during sexual intercourse, and they may experience symptoms. Symptoms in women include lower abdominal cramping and pain, discomfort, painful sex, and discharge. Complications may include Pelvic Inflammatory Disease (PID), endometritis (infection of the uterus), salpingitis (infection of the Fallopian tubes) or oophoritis (infection of the ovaries). IUD placement increases the risk for infection. Complications of PID include scarring, pain, sterility, ectopic pregnancy, abscesses, peritonitis, or peri-hepatitis. Rarely, it can even cause gonococcal bacteremia or septic arthritis in both sexes.
Untreated pregnant women can transmit the bacteria to the newborn during childbirth and delivery, where it can cause a purulent eye infection that can damage the cornea, resulting in blindness. Gonococcal eye conjunctivitis can occur in adults as well. It can be treated with antibiotics and antibiotic eye drops.
Collection includes using a special, ultra thin, flexible swab of the urethral discharge, which is sent immediately to the laboratory for testing. Colonies grow as small, transparent, and have lobate margins.
Characteristics:
Untreated pregnant women can transmit the bacteria to the newborn during childbirth and delivery, where it can cause a purulent eye infection that can damage the cornea, resulting in blindness. Gonococcal eye conjunctivitis can occur in adults as well. It can be treated with antibiotics and antibiotic eye drops.
Collection includes using a special, ultra thin, flexible swab of the urethral discharge, which is sent immediately to the laboratory for testing. Colonies grow as small, transparent, and have lobate margins.
Characteristics:
- Gram-negative diplococci shaped like 2 kidney beans or coffee beans facing each other
- Fastidious
- Grow on Chocolate Agar, Thayer Martin, Martin Lewis, MTM, NYC medium, JEMBEC system
- Facultative intracellular organisms
- Obligate aerobe
- Nonmotile (has no flagella, but does produce twitching motility due to pili)
- Oxidase positive
- In the sugars test, only ferments glucose
- Possesses pili and twitching motility
- Protein II is an adhesin that enables the bacterium to stick to mucosa
- Cultures, Gram-stain, and nucleic acid probe aid in identification
- Cefixime
- Ceftriaxone
- Ciprofloxacin
- Ofloxacin
- Spectinomycin
- Doxycycline
- Norfloxacin
neisseria meningitidis:
Neisseria meningitidis is the causative agent of bacterial meningitis. It can cause life-threatening sepsis as well (meningococcemia). This results in fevers, chills, joint and muscle pains, and a petechial rash. The bacteria can spread throughout the bloodstream, crossing the blood-brain barrier to result in meningitis. Fulminant meningococcemia is referred to as Waterhouse-Friderichsen syndrome. It results in septic shock and hemorrhage into the adrenal glands, which sit atop the kidneys. This causes the blood pressure to drop drastically (hypotension) and the heart to race (tachycardia), and the skin rash lesions enlarge. Spread can lead to disseminated intravascular coagulation (DIC), coma, and even death within hours. However, the most common form of the disease is meningitis amongst infants of <1 year of age. Infants present with spiking fevers, vomiting, irritability and lethargy. The anterior fontanelle may be bulging, which is a classic sign of meningitis in the neonate. Older infants and toddlers may also present with a stiff neck, sensitivity to light, and a positive Kernig's and Brudzinski's sign. If a class petechial rash accompanies these signs and symptoms, the physician will presumptively treat the condition as if it were meningitis prior to performing the spinal tap and cultures for confirmation. Often times, the physician will order a STAT CSF Gram stain first to determine where infection is truly bacterial or viral, then begin treatment immediately.
The microbiology gold standard is the culture of a sterile body fluid such as CSF or blood. Specimens are plated to Chocolate agar or Thayer-Martin or Modified Thayer-Martin media, which includes antibiotics to inhibit growth of other organisms. These include vancomycin, colistin, and nystatin. Media is cultured in a high concentration of CO2. High-risks groups include military recruits and newborns ages 6 months to 2 years. Treatment of choice is Penicillin G or ceftriaxone or rifampin.
Characteristics:
The microbiology gold standard is the culture of a sterile body fluid such as CSF or blood. Specimens are plated to Chocolate agar or Thayer-Martin or Modified Thayer-Martin media, which includes antibiotics to inhibit growth of other organisms. These include vancomycin, colistin, and nystatin. Media is cultured in a high concentration of CO2. High-risks groups include military recruits and newborns ages 6 months to 2 years. Treatment of choice is Penicillin G or ceftriaxone or rifampin.
Characteristics:
- Gram-negative diplococci (bean-shaped)
- Aerobic
- Motile (twitching motility)
- 5-10% of adults may carry this organism in their nares (asymptomatic carriers)
- Oxidase positive
- Catalase positive
- Have a polysaccharide capsule
- Ferments glucose and maltose sugar tubes
- Extremely fastidious
- Minimum of 48-72 hours turnaround time and up to a week for serotyping
- Encapsulated
- Endotoxin LPS
- Causes blood vessel destruction, hemorrhage, sepsis, skin rash as tiny, round, red dots called petechiae
- Can damage the adrenal glands of the kidneys
- IgA1 protease (destroys IgA of the immune system)
- Iron-chelater (steals iron from the host)
- CSF culture, Gram-stain, and latex agglutination test aid in identification
- Penicillin G
- Cephalosporins
- Chloramphenicol
Neisseria sicca:
N. sicca has many of the same characteristics of other Neisseria species, but it may cause sepsis in immunocompromised individuals. It is also Gram-negative diplococci and is oxidase positive. Colonies are small, round, smooth, convex, shiny and are orange-like on Chocolate and blood agars.
Neisseria subflava:
Neisseria subflava is normally nonpathogenic and a typical part of the normal oropharyngeal flora. It is also Gram-negative diplococci, oxidase positive, resembles N. sicca, and causes rare post-surgical site infections and postoperative meningitis after a neurological type of surgery.
nocardia asteroides:
Nocardia asteroides is the causative agent of the illness nocardiosis. This causes a slowly progressing pneumonia in humans with cough, shortness of breath, fever, and sometimes pleurisy. It can also cause endocarditis, brain abscess, skin infections and abscesses, and cellulitis. Sometimes it can be recovered on BCYE medium. It resembles fungi, because it produces branching hyphae, which fragment into cocci and rod-like elements. It is found mostly in soil and on vegetation. It is mostly an opportunistic pathogen that infects the immunosuppressed or immunocompromised. Inhalation of aerosolized droplets containing the microbe is what causes pulmonary nocardiosis, or chronic pneumonia. It can spread throughout the bloodstream and affect the central nervous system and other organs. It can also cause cellulitis and keratitis.
Characteristics:
Characteristics:
- Weakly Gram-positive branching bacilli
- Nonmotile
- Catalase positive
- Acid-fast
- Strict aerobes
- Slow growers
- Grow pretty well on Nocardia Quad Media
- Urease positive
- Ticarcillin with clavulanate
- Ampicillin with sulbactam
- Piperacillin with tazobactam
- Cefoxitin
- Cefotetan
- Carbapenems
- Clindamycin with a cephalosporin
- Fluoroquinolone with Metronidazole or clindamycin
parvimonas:
pasteurella species:
Pasteurella multocida is a zoonotic pathogen that can cause human infections from bite wounds, particularly domestic dog bite wounds and sometimes cat bite wounds, as this is the normal commensal flora of their mouths. It is also sometimes transmitted via animal scratches as well. Colonies grow as gray-yellow, smooth, glistening, small, transparent, gamma-hemolytic on blood agar and have a musty odor to them.
Characteristics:
Characteristics:
- Gram-negative pleomorphic bacilli (small, ellipsoidal to elongated rods) in singles, pairs, and chains (rarely)
- Facultative anaerobe
- Nonmotile
- Bipolar staining ("safety pin" appearance)
- Oxidase positive
- Catalase positive
- P. multocida is indole +
- Ferments glucose, sucrose, maltose
- Causes cellulitis, swelling, pus and drainage, possible arthritis, possible abscess
- Chloramphenicol
- Penicillin
- Tetracycline
- Macrolides
peptococcus:
Characteristics:
- Anaerobic Gram-positive cocci occurring singly and in pairs, tetrads, irregular masses
- Produces tiny, convex, shiny, smooth, circular, black or light gray colonies on ANABAP
peptoniphilus:
peptostreptococcus:
Characteristics:
- Anaerobic Gram-positive cocci or large coccobacilli, often in chains; larger than most other anaerobic cocci
- Growth is medium gray-white, translucent-to-opaque, nonhemolytic colonies with a sweet or fetid odor
- Susceptible to vancomycin
- P. anaerobius
- Indole negative
- Catalase negative
- Smells sweet and putrid at the same time
- Cocci and coccobacilli may chain
- Indole negative
- P. asaccharolyticus
- Indole positive
- Catalase variable
- Indole odor
- Indole positive
plesiomonas:
Plesiomonas species is a ubiquitous Gram-negative bacilli often recovered from freshwater. It can cause gastroenteritis and diarrhea in humans. It is oxidase positive and negative for DNAse.
porphyromonas species:
Porphyromonas species are Gram-negative, anaerobic coccobacilli that are dark brown to black on ANABAP agar, are more mucoid than Prevotella species, and most strains fluoresce brick red under UV light.
Other characteristics:
Other characteristics:
- Kanamycin Resistant
- Vancomycin Susceptible
- Colistin Resistant
- BE -
- Indole +
- Catalase -
- Black pigmented colonies
- Fluoresces brick red
- Nonmotile
- Urease -
prevotella species:
Prevotella are a species of Gram-negative, pleomorphic bacteria that are part of the commensal flora of the nasopharynx and the urogenital tracts. They cause anaerobic respiratory infections, including aspiration pneumonia, lung abscess, pulmonary empyema, chronic otitis media (middle ear infection), sinusitis, burns, bites, urinary tract infections, bacterial vaginosis, brain abscesses, osteomyelitis, bacteremia, upper respiratory infections, atherosclerosis, periodontal disease and periodontal abscesses.
Prevotella melaninogenica produces black colonies on blood agar surrounded by gray or light brown edges that are convex, circular, entire, smooth, shiny, and non hemolytic, and they fluoresce brick red under UV light.
Prevotella melaninogenica produces black colonies on blood agar surrounded by gray or light brown edges that are convex, circular, entire, smooth, shiny, and non hemolytic, and they fluoresce brick red under UV light.
- P. intermedia
- Susceptible to Colistin
- BE -
- Indole +
- Catalase -
- Lipase +
- P. loescheii
- Resistant to Colistin
- BE -
- Indole -
- Catalase -
- Lipase -
- Other
- Resistant to Kanamycin and Vancomycin
- Pigmented colonies
- Fluoresce brick red
- Nonmotile
- Urease -
proteus mirabilis:
Proteus mirabilis is a Gram-negative bacilli and facultative anaerobe and member of the Enterobacteriaceae. It is found in the soil and contaminated water as well. It is known for its characteristic swarming ability and "chicken soup" odor and urease activity. It causes about 90% of all Proteus infections in humans. It is ubiquitous. It is a non-lactose fermenter, and it causes the urine to become alkaline. It also produces H2S gas. It is also motile and exhibits swarming motility, resulting in distinct concentric rings on the agar plate.
P. mirabilis is linked to nosocomial infections. Infection with this organism (UTI) is linked to kidney stone formation (struvite, apatite, calcium carbonate). Other infections associated with this bacterium include wound infections, burn infections, pneumonia, and septicemia. Rarely, they may be associated with gastroenteritis and diarrhea. It is generally susceptible to most antibiotics, however, some MDROs exist.
Complications of UTIs in susceptible and weakened individuals can actually be deadly.
Characteristics:
P. mirabilis is linked to nosocomial infections. Infection with this organism (UTI) is linked to kidney stone formation (struvite, apatite, calcium carbonate). Other infections associated with this bacterium include wound infections, burn infections, pneumonia, and septicemia. Rarely, they may be associated with gastroenteritis and diarrhea. It is generally susceptible to most antibiotics, however, some MDROs exist.
Complications of UTIs in susceptible and weakened individuals can actually be deadly.
Characteristics:
- GNR (straight) in singles, pairs, and short-to-long chains (pleomorphism in young colonies)
- Facultative anaerobe
- NLF
- H2S
- Very motile, especially at 25 degrees Celsius (but may be absent or weak at 37 degrees Celsius)
- Swarmer (swarming motility)
- Chicken Soup Scent (putrid odor)
- Indole negative (NOTE: some strains may produce indole)
- Oxidase negative
- Catalase positive
- Urea positive (urea-splitting)
- Bile esculin negative
- Ferments glucose
- Alkaline pH
- Cephalosporins
- Carbapenems
- Fluoroquinolones
- Extended spectrum penicillins
proteus vulgaris:
Characteristics:
- GNR
- NLF
- Swarmer
- Indole positive
- Catalase positive
- H2S positive
- Causes UTI
- Causes wound infections
- Motility +
- Ferments glucose
- Gas production +
- Urease +
- Alkaline urine
- Associated with urinary catheter-associated UTI
- Has been known to cause sinus infection or respiratory infection
providencia:
Providencia species are not very pathogenic but they can cause opportunistic infections, including UTI and gastroenteritis, wound or burn infections.
Characteristics:
Characteristics:
- GNR (straight)
- NLF
- Don't produce H2S
- Indole +
- Citrate +
- Motile
- Facultative anaerobe
- Causative agent of UTI (urinary catheter-associated)
- Wound/burn infections
- Ampicillin is treatment of choice
- P. stuartii and P. alcalifaciens are urease negative
- P. rettgeri is urease positive
pseudomonas aeruginosa:
Pseudomonas aeruginosa is a member of the Enterobacteriaceae. It is a Gram-negative bacilli that produces a metallic sheen and greenish pigment on agar due to the production of the pigment pyocyanin, pyoverdine, and fluoroscein. It also has a "fruity" scent ("grape-like" or "tortilla-like"). It is ubiquitous and it is found in soil, water, living and decaying plant matter. It is an opportunistic pathogen, often a MDRO, and is associated with a number of serious illnesses ranging from UTI to wound/burn infections, puncture wound, osteomyelitis, respiratory infections, hospital-acquired infections, ventilator-associated pneumonia, and sepsis. Burn patients, those with Cystic Fibrosis, and the immunocompromised are at highest risk for infection. It can also cause hot tub folliculitis and "Swimmer's Ear" (otitis externa). It can make biofilms and is associated with medical equipment colonization and indwelling catheter and other types of infections. It can cause corneal ulcers and damage the eye, possibly even causing blindness. Puncture wound infections with this bacterium have led to cases of osteomyelitis.
This organism has been isolated from hospital equipment, including surfaces, sinks, tubs, whirlpools, dialysis equipment, contact lens solution, aerators, irrigation fluids, ointments, shoe insoles, soaps, cleaning solutions, furniture, ceilings, and is the most significant opportunistic pathogen in its genus. It is difficult to kill and survives harsh conditions. It can be transmitted via ingestion of contaminated material, inhalation of aerosolized particles, or through openings in the skin like wounds or burns.
Virulence factors this microbe possesses include pili for attachment and secretion of tissue-damaging enzymes.
Characteristics:
This organism has been isolated from hospital equipment, including surfaces, sinks, tubs, whirlpools, dialysis equipment, contact lens solution, aerators, irrigation fluids, ointments, shoe insoles, soaps, cleaning solutions, furniture, ceilings, and is the most significant opportunistic pathogen in its genus. It is difficult to kill and survives harsh conditions. It can be transmitted via ingestion of contaminated material, inhalation of aerosolized particles, or through openings in the skin like wounds or burns.
Virulence factors this microbe possesses include pili for attachment and secretion of tissue-damaging enzymes.
Characteristics:
- GNR (straight or slightly curved)
- Aerobic
- NLF
- Ferments glucose
- Bile esculin negative
- Urease negative
- Fruity Odor
- Metallic or green sheen due to production of a diffusible pigment called pyocyanin or pyoverdin
- Dry, Spreading, Irregular Colonies
- Twitching motility
- Oxidase positive
- Catalase positive
- Ceftazidime
- Aminoglycosides
- Extended spectrum penicillins
- Cefepime
- Fluoroquinolones
- Ciprofloxacin
Raoultella species:
Characteristics:
- Gram-negative bacilli
- Oxidase negative
- Aerobic
- Nonmotile
- Encapsulated
- Facultative anaerobe
salmonella species:
Salmonella species are serious human pathogens responsible for the illness salmonellosis. It is a type of food poisoning usually caused by ingesting contaminated beef or poultry or vegetables. Domesticated pets such as cats and hamsters and gerbils have also been known to carry the bacterium, so care should be taken to wash one's hands after handling pets, especially prior to eating. Even vacuum cleaner bags can serve as a reservoir for the bacterium. Contaminated raw eggs are a source for transmission. Pasteurization and irradiation of foods like dairy products are used to kill the bacterium. Foods containing raw eggs, such as mayonnaise, cookies, cakes must be properly cooked, handled and stored in order to protect yourself from infection. It causes gastroenteritis with diarrhea and nausea and cramping. The major complication that can occur are bloodstream infections and sepsis. Sometimes, the liver and spleen can become enlarged as well, causing tenderness and pain. Salmonella food poisoning is a reportable disease. Those working on the stools bench and blood culture bench will likely be the first to see this organism in infections.
Characteristics:
Characteristics:
- Gram-negative bacilli
- Motile
- Non-spore-forming
- Facultative anaerobe
- Non-lactose-fermenter
- Produces H2S gas
- On Hektoen agar: grows as blue-green colonies with black centers
- On XLD and MAC agars: grows as colonies with large black centers (non-lactose-fermenter)
- Intracellular pathogen
A picture-perfect example of Salmonella colonies growing on Hektoen (HEK) agar is shown here. Salmonella produces blue-green colonies with black centers due to H2S gas production;By The original uploader was Philippinjl at French Wikipedia - Transferred from fr.wikipedia to Commons by Bloody-libu using CommonsHelper., CC BY-SA 2.0 fr, https://commons.wikimedia.org/w/index.php?curid=17397507
salmonella typhi:
S. typhi isa member of the Enterbacteriaceae. It is the causative agent of typhoid fever, and is spread via the fecal-oral route by contaminated food or water, attacking the epithelial cells of the small intestine. It produces bacteremia once it gets into the bloodstream. High fever, chronic diarrhea, and shedding of the bacteria with the feces can occur for a long time with this illness.
Characteristics:
Characteristics:
- Straight GNR
- Motile
- Encapsulated
- Facultative anaerobe
- Non-spore-forming
- Serogrouping is done by a reference laboratory
- Cephalosporins
- Ampicillin
- Sulfamethoxazole/Trimethoprim
- Chloramphenicol
- Ciprofloxacin
serratia marcescens:
Serratia is a Gram-negative enteric bacilli known for its bright red pigment production. It is linked to urinary tract infections, wound infections, and pneumonia.
Shigella species:
Shigella species is responsible for cases of shigellosis worldwide. Infection occurs by ingestion of contaminated food or water, and ingestion of just 100 cells or less can cause illness. The bacteria invades the epithelial cells of the colon, producing severe inflammation and tissue necrosis (death). This causes diarrhea and dysentery. Symptoms appear about 2-4 days after ingestion, and symptoms last anywhere from 3 days to 1 week. It can also cause reactive arthritis. Unfortunately, this bacterium is resistant to the highly potent hydrochloric acid in the stomach, so it survives the journey to the intestines. There, the bacteria multiplies and spreads and ulcerates the mucosa, causing an immune response and resulting in pus, purulent bloody diarrhea, and cramping pain associated with the illness.
Characteristics:
Characteristics:
- Gram-negative bacilli
- Facultative anaerobes
- Non-spore-forming
- Late lactose fermenter
- Nonmotile
- No H2S gas
- Some strains produce indole and others do not (indole-variable)
- Causative agent of shigellosis: diarrhea, fever, cramps, nausea, vomiting, and gas with painful bowel movements that may contain blood, mucus and/or pus
- Causative agent of dysentery (moderate-to-severe diarrhea) and dehydration; Young children have been known to have convulsions or seizures
- Contain virulence plasmids
- Share many genes with E. coli
- Produces toxins
- 4 major serogroups:
- S. dysenterie (15 serotypes)-Group A
- Accounts for epidemics/outbreaks of dysentery, which is transmitted via the fecal-oral route by the ingestion of contaminated food or water, or by direct person-to-person contact
- Highly communicable and virulent
- Produces the shiga toxin, a potent enterotoxin similar to the verotoxin produced by E. coli O157:H7 strain, which is linked to the fatal hemolytic uremic syndrome (HUS)
- Straight GNR
- Nonmotile
- Facultative anaerobe
- Non-lactose-fermenter
- Does not ferment mannitol, sucrose, xylose, or raffinose
- Fecal leukocyte stain is positive for presence of leukocytes and red blood cells
- S. flexneri (6 serotypes)-Group B
- Most frequently isolated in culture worldwide
- Accounts for about 60% of cases in the developing world
- Produces 2 potent toxins: ShET 1 and ShET2
- S. boydii (19 serotypes)-Group C
- S. sonnei (just 1 serotype)-Group D
- Accounts for about 77% of cases in the developed world and about 15% in the developed world
- S. dysenterie (15 serotypes)-Group A
- Cephalosporins
- Ampicillin
- Sulfa/Trimethoprim
- Ciprofloxacin
- Fluoroquinolones
shigella dysenteriae:
shigella:
sphingomonas paucimobilis:
Characteristics:
- Gram-negative bacilli
- Obligate aerobe
- Orange colonies on blood agar
- Linked to nosocomial infections
staphylococcus aureus:
Staphylococcus aureus means "golden staph", since the bacterium produces golden colonies on blood agar. Colonies are beta-hemolytic, producing large zones of hemolysis around the colonies. S. aureus is also catalase positive. It is a normal human skin flora. It is one of the most common nosocomial pathogens and has a number of virulence factors, including antiphagocytic proteins, lipase production, coagulase, enterotoxins, and exotoxins. It can be transmitted via direct contact, aerosolized particles, or environmental factors. It often survives cleaners, disinfectants, sanitizers, antibiotics, travels far in aerosolized particles, and can survive for weeks on surfaces or in the environment. It is quite hardy!
Characteristics:
Characteristics:
- Gram-positive cocci in clusters (tetrads and sarcinae when dividing)
- Catalase positive
- Nonmotile
- Staphaurex latex test positive (clumping) most of the time, but not always
- Slide test (bound coagulase)
- Tube test (free coagulase)
- Facultative anaerobe
- Beta-hemolytic (large zones)
- Ferments mannitol to produce bright yellow colonies on MSA
- Normal flora of the skin, nose, respiratory tract (commensal)
- Causes opportunistic infections (skin, respiratory, urinary tract, sepsis/bacteremia, wound, sinusitis, food poisoning), so every bench will encounter and work up this organism
- MRSA is the MDR strain
- Responsible for infections such as pimples, boils, folliculitis, carbuncles, furuncles, cellulitis, abscesses, scalded skin syndrome
- Linked to life-threatening illnesses, including pneumonia, meningitis, endocarditis, osteomyelitis, toxic shock syndrome, bacteremia, sepsis
- Linked to nosocomial infections, especially post-surgical wound infections and septic arthritis
- Linked to food poisoning, and incubation period is just 1-6 hours after eating contaminated food, with illness lasting 30 minutes to 3 days
- Biofilm formation
- Colonization of medical equipment, catheters, replacement joints, orthotics, etc...
- Produces toxins
- Produces lysins
- Produces potent enzymes, including coagulase, hyaluronidase, deoxyribonuclease, staphylokinase, beta-lactamase, DNAse, Lipase, phosphatase
- Produces potent exotoxins:
- TSST1 and enterotoxin type B: Toxic Shock Syndrome
- Enterotoxin: gastroenteritis
- Exfoliative toxin: scalded skin syndrome
- Alpha toxin
- Beta toxin
- Delta toxin
- PVL toxin: necrotizing pneumonia
- Produces several pigments: staphyloxanthin (gold)
staphylococcus epidermidis:
S. epidermidis is a Gram-positive cocci that is part of the normal commensal flora of the human skin. It is part of the coagulase negative staphylococci. It is usually not pathogenic, but it can cause opportunistic infections in hospitalized patients, the immunocompromised, and can also cause urinary tract infections. Usually, these infections are nosocomial (hospital-acquired). S. epidermidis is associated with catheter-associated infections, surgical implant infections, prosthesis, endocarditis due to contaminated artificial heart valves, even sepsis and others because of its ability to form biofilms, slime layers and colonize equipment. Infections can be severe and even fatal for patients who are already immunocompromised.
Characteristics:
Characteristics:
- Gram-positive cocci in clusters
- Gray-white, convex, smooth, shiny, cohesive, round colonies on blood agar
- Non-hemolytic
- Nonmotile
- Catalase positive
- Coagulase negative
- Novobiocin susceptible
- Facultative anaerobe
- Urease positive
- Oxidase negative
- Ferments maltose
- Produces gas from lactose
- Susceptible to novobiocin in the novobiocin disk test
- Treatment is vancomycin with rifampin or an aminoglycoside for infection
staphylococcus saprophyticus:
Staphylococcus saprophyticus is a Gram-positive cocci in clusters that produces creamy white, convex, round, smooth, shiny, non hemolytic colonies on blood agar. It is a member of the coagulase-negative staphylococci (CNS). It is a common cause of community-acquired urinary tract infection (UTI), particularly among young women of child-bearing age second to E. coli. It is a normal part of the commensal flora of the urogenital tract of females and of the perineum and GI tract. Of all urinary tract infections, this bacterium is responsible for about 10-20% of cases. Sexual activity is linked to UTI by this organism since the bacteria become displaced into the urethra, causing infection in just 24 hours. It is responsible for cystitis, "honeymoon cystitis", with a burning sensation when urinating, urinary frequency, urinary urgency, urinary dribbling, weak bladder, feeling bloated, cramping, and flank pain (side). When working up this organism, look up the urinalysis results for positive leukocytes, presence of red blood cells (erythrocytes), and sediment. It does not reduce nitrate, so this test will not be positive. Low numbers of CFU/mL may be seen.
Characteristics:
Characteristics:
- GPCC
- Coagulase negative
- Catalase positive
- Novobiocin-resistant
- PYR negative
- Treatment: Trimethoprim-Sulfa or Norfloxacin or another quinolone or Ampicillin or Ceftriaxone
stenotrophomonas maltophilia:
S. maltophilia is an aerobic, Gram-negative bacilli and non-lactose-fermenter that is motile and produces pigmented colonies. It is a rare cause of nosocomial infection, but it is inherently a MDRO. It is oxidase negative and catalase positive. It is ubiquitous. It has the ability to colonize equipment, such as the tubing in mechanical ventilators, indwelling urinary and medical catheters, and things like endoscopes. Metal or plastic prosthetic material is at risk for biofilm formation and colonization, which can transmit the microbe to humans during surgery or treatment. If blood cultures come up positive with this organism, then a true infection exists. Infections caused by the organism include UTI, pneumonia, and bloodstream infections. Morbidity and mortality rates are high when those who are immunocompromised become infected with this microbe.
streptococcus groups c, f, and g beta-hemolytic:
Members of the beta-hemolytic streptococci groups C, F and G are occasionally implicated in acute pharyngitis with similar symptoms of that caused by Group A streptococci (S. progenies) but many resolve on their own without antibiotics. These bacteria are part of the normal flora of the human skin, nasopharynx, GI tract, and genital tract. If the isolates gain access to a sterile site, or the person is exposed to someone with an active infection, they can become infected as well. Most of these infections occur in those who are already immunocompromised or have an underlying malignancy, particularly those linked to group G. Group C organisms are associated with acute pharyngitis similar to that of GAS. Most are susceptible to penicillin, and vancomycin is an option for those allergic to penicillin.
- Group C beta-hemolytic streptococci
- Gray-white, glistening colonies surrounded by a wide zone of beta-hemolysis
- S. dysgalactiae
- S. milleri group
- Group F beta-hemolytic streptococci
- Gray-white, small, matte colonies surrounded by a narrow-to-wide zone of beta-hemolysis
- S. milleri group
- S. anginosus
- S. constellatus
- S. intermedius
- Group G beta-hemolytic streptococci
- Gray-white, matte colonies surrounded by a wide zone of beta-hemolysis
- S. dysgalactiae
- S. milleri group
- S. canis
streptococcus agalactiae:
Streptococcus agalactiae is also known as Group B Strep. Up to 36% of women may be colonized with the microbe. Normally, this causes no problems or symptoms, however, if a woman is pregnant, it can cause problems in the neonate or newborn, as well as for the mother during labor and delivery. In fact, it is the #1 cause of bacterial neonatal infection in the neonate during gestation and newborn following delivery. Mortality rates can be high, especially if the baby is born prematurely. In the mother, should an infection occur, it can cause chorioamnionitis, which can result in premature delivery, miscarriage or even stillbirth. It can also cause postpartum infections in the mother, which can also prove fatal. A urinary tract infection during pregnancy with this organism may result in early labor and delivery. In the newborn, it can cause sepsis, pneumonia, meningitis with fever, vomiting, irritability, or even death. For this reason, pregnant women are swabbed around 35-37 weeks of gestation and the swab is cultured to detect for the presence of colonization with the microbe, so that she can be treated prophylactically with antibiotics ahead of time or during delivery (IV drip antibiotics). Penicillin or ampicillin are the drug of choice, but if the woman is allergic to penicillin, she can receive cefalozin, clindamycin or vancomycin instead.
Other types of infections can occur in the elderly, those with liver cirrhosis, immunocompromised and diabetic patients: UTI, skin and soft tissue infection, bacteremia, osteomyelitis, meningitis, endocarditis. These infections can be or become serious and result in mortality.
Characteristics:
Other types of infections can occur in the elderly, those with liver cirrhosis, immunocompromised and diabetic patients: UTI, skin and soft tissue infection, bacteremia, osteomyelitis, meningitis, endocarditis. These infections can be or become serious and result in mortality.
Characteristics:
- GBS
- GPC in chains
- Nonmotile
- Beta-hemolytic (narrow zone)
- NOTE: some strains are non hemolytic, so don't always rely on this
- Catalase negative
- Facultative anaerobe
- Commensal microbiota of the human urogenital tract and GI tract (asymptomatic carriers)
- Encapsulated with polysaccharide capsule
- The PathoDx latex agglutination test can be used to group the streptococci
- CAMP test positive
- Hippurate positive
- PYR negative
- Bacitracin resistant
- SXT resistant
- Orange colonies on Granada agar medium
- Penicillin G
- Amoxicillin
- Ampicillin
- Cephalosporins
- Erythromycin
- Vancomycin
streptococcus Group D:
streptococcus pyogenes:
Streptococcus pyogenes is a Gram-positive cocci with the tendency to form chains, which is the causative agent of infections such as bacteria "Strep Throat". It can also cause Scarlet Fever, skin infections, impetigo, necrotizing fasciitis (rare), sepsis, toxic shock syndrome (TSS), erysipelas, cellulitis, mastoiditis, neonatal infections, rheumatic fever, glomerulonephritis. It is a member of the Group A streptococci and possesses the Lancefield antigen A on its surface.
Characteristics:
The treatment of choice is still penicillin or amoxicillin, however, if the individual is allergic to penicillin, alternative antibiotics can be given instead.
Characteristics:
- GAS
- GPC in chains
- Aerotolerant
- Nonmotile
- Beta-hemolytic
- Ferments lactose, salicin, trehalose
- PYR positive
- Hippurate negative
- Part of the skin microflora
- Lancefield A antigen
- Catalase negative
- M protein virulence factor
- Surface T antigen (pili): adherence to cells
- Encapsulated
- Lipoteichoic acid
- Protein F
- Exotoxin: Streptolysin O
- Cardiotoxic Exotoxin: Streptolysin S
- Streptococcal pyrogenic exotoxin A: responsible for the rash of Scarlet Fever and streptococcal toxic shock syndrome (TSS)
- Streptokinase
- Hyaluronidase
- Streptodornase
- C5a peptidase
- Chemokine protease
The treatment of choice is still penicillin or amoxicillin, however, if the individual is allergic to penicillin, alternative antibiotics can be given instead.
streptococcus pneumoniae:
Streptococcus pneumoniae is is a Gram-positive, alpha-hemolytic bacterium whose morphology is Gram-positive lancet-shaped cocci in pairs. It is an aerobe, sensitive to optochin disk test, nonmotile, encapsulated, and a facultative anaerobe. It causes bacterial pneumonia, among other infections. It can exist as part of the normal flora of the nasopharynx, without causing symptoms. Asymptomatic carriers are often unaware of its presence when it causes no symptoms, and it may be carried by up to 75% of the population without problem. However, in susceptible individuals whose immune system has become weakened due to underlying illness, cancer, or other condition, it can become pathogenic and cause an opportunistic infection. It can cause respiratory infections, ear infections, neonatal infections, community-acquired pneumonia, meningitis in children and older individuals, and septicemia. It can also cause rhinitis, bronchitis, sinusitis, middle ear infections, eye infections, bone infections, septic arthritis, endocarditis, pericarditis, peritonitis, cellulitis, or even a brain abscess.
Characteristics:
Characteristics:
- Gram-positive cocci in lancet-shaped pairs (elongated, pointed)
- Alpha-hemolytic
- Nonmotile
- Encapsulated
- Facultative anaerobe
- Bile esculin negative
- Does not ferment mannitol or sorbitol
- Susceptible to optochin disk
- Urease negative
- Mucoid/raised or flat/dry strains
- Rapid streptococcus antigen test may be used to aid in identification
treponema pallidum:
Treponema pallidum is a spirochete that causes syphilis, an STD. It is visible only with dark field microscopy. It is a human pathogen. It causes >100,000 cases a year in the USA alone. It can be treated with penicillin. There are 3 stages: primary, secondary and tertiary. Primary phase lasts 2-6 weeks and begins with a sore called a "chancre". At this time, the bacteria rapidly multiplies and spreads to all body regions and to the central nervous system. After this stage, an asymptomatic period lasting up to 6 months may follow. The secondary stage is characterized by the formation of lesions throughout the body, including the liver, lymph nodes, muscles and skin. Another asymptomatic period follows, lasting 5 years to 30 years. The tertiary stage is the final stage and is characterized by destruction of nerve and cardiac cells and tumors form throughout the body.
Characteristics:
Characteristics:
- Gram-negative spirochete (helical rod)
- Motile
- Microaerophilic
- Darkfield microscopy needed to view it
- Serology testing needed
veillonella:
Veillonella species, particularly V. parvula, is a Gram-negative, tiny diplococci in clusters, pairs, and short chains, and is an anaerobe. It ferments lactate. Rarely, it causes infective endocarditis and osteomyelitis in humans, as well as periodontal infections. Typically these infections are polymicrobial. On ANABAP agar, it grows as small, transparent, grayish-white colonies that are smooth, entire, opaque, butyrous and may fluoresce red under UV light.
Other Characteristics:
Other Characteristics:
- Susceptible S. dysgalactiae on blood agar grow as flat, small, white colonies surrounded by a wide zone of beta-hemolysis Kanamycin and Colistin
- Resistant to Vancomycin
- BE-
- Indole -
- Catalase variable
- Non-pigmented
- Does not fluoresce brick red
- Nonmotile
- Urease -
- Nitrate reduction +
vibrio cholerae:
Vibrio cholerae is a comma-shaped, Gram-negative, motile bacterium that causes cholera, a gastroenteritis with rice water diarrhea, fever, vomiting, severe abdominal cramps, malaise, fatigue, weakness and dehydration. Usually, other species of Vibrio cause food borne illness. They are found in seawater and typically cause infections from eating undercooked seafood. They are facultative anaerobes, oxidase positive, motile, and have polar flagella. The bacterial species can also infect wounds and even cause septicemia. V. parahaemolyticus and V. vulnificus are more common and result in a less invasive and self-limiting gastroenteritis transmitted by contaminated water or by eating raw shellfish. Some strains are beta-hemolytic. Doxycycline or a quinolone are the preferred treatment of choice, along with aggressive IV replacement fluid therapy with electrolyte replacement.
Characteristics:
Characteristics:
- Gram-negative, comma-shaped bacteria
- Oxidase positive
- Beta-hemolytic on blood agar
- Motile
- Facultative anaerobe
- Sulfa/Trimethoprim
- Tetracycline
- Doxycycline
viridans group streptococci:
The Viridans Group Streptococci have no Lancefield antigens on their surface. They are microaerophilic Gram-positive cocci in chains and most are alpha-hemolytic on blood agar. Most are included as part of the human commensal microflora of the oral and upper respiratory tract, GI tract, and female genital tract and are typically contaminants of laboratory cultures, but some are associated with opportunistic infections when they gain access to normally sterile sites. They are typically considered to be of low virulence. Their ability to colonize cell surfaces, however, is due to the production of extracellular complex polysaccharides like glucans or dextran, which enhance their attachment to cells or tooth surfaces. Viridians streptococci produce tiny or small gray, convex, smooth or matte, alpha or gamma-hemolytic colonies on blood agar. For true infections, the bacteria are usually susceptible to penicillin or ceftriaxone. If the individual has a penicillin allergy, then vancomycin is an option.
Members include the following:
Members include the following:
- Streptococcus salivarius group
- Streptococcus sanguis group
- Streptococcus mitis group (dental infections, gingivitis)
- Streptococcus intermedius group (S. intermedius, S. constellatus, S. anginosus)
- If one of the members of this group grows in multiple blood cultures, an abscess is likely hiding somewhere
- S. anginosus sometimes causes urinary tract infections (UTI)
- Streptococcus mutans group
- Member of the "mutans" group
- Can cause subacute endocarditis in those with prosthetic heart valves or heart valve problems
- Can cause bacteremia after a dental or urogenital invasive procedure
- Causes dental plaque and cavities
- Beta-hemolytic
- Nonmotile
- Facultative anaerobe
- Treat with Penicillin G, Vancomycin, or Cephalosporins
- Streptococcus milleri group
- Streptococcus bovis group
- Others
yersinia enterocolitica:
Characteristics:
- Gram-negative bacilli
- Motile only at 22-29 degrees, but not at body temperature
- Causes yersiniosis (enteritis and watery or bloody diarrhea, fever and occasionally reactive arthritis)
- Infection occurs by ingestion of undercooked pork, meat, milk or water
- Green-blue colonies on HEK agar
- Raised, shiny, round, smooth, convex white colonies on XLD or blood agar
- Target (bull's eye) colonies on Yersinia CIN agar
yersinia pestis:
Yersinia pestis is the causative agent of bubonic plague, pneumonic plague, and septicemic plague. It is a Gram-negative coccobacillus, nonmotile, and non-spore-forming. It is a facultative anaerobe. It is carried by a vector called the rat flea. Throughout history, this organism has caused many outbreaks, epidemics, and has killed many people. During the 6th century, the Black Death killed at least 1/3rd of Europe's population. This occurred in the mid-1300's. The Third Pandemic, or Modern Plague, in the 19th century also spread and killed about 10 million people. This plague originated in China and spread rapidly by rats. The bacterium itself wasn't discovered until 1894 during an epidemic outbreak in Hong Kong. In the USA, the black-tailed prairie dog and endangered black-footed ferret, marmot, and some domesticated cats may carry the organism.
Characteristics:
Characteristics:
- GNCB or short rod
- Facultative anaerobe
- Nonmotile
- Bipolar staining ("safety-pin appearance")
- Slime layer
- Indole negative
- Urease negative
- Lactose negative
- Forms an envelope when incubated at 37 degrees Celsius
- Colonies look like "fried eggs" on sheep blood agar
- Does not ferment sucrose, rhamnose or cellobiose