Escherichia coli on MacConkey agar: 2 strains: left (lactose-fermenting strain), right (non-lactose-fermenting strain)
Klebsiella pneumoniae
Prevotella spp
Prevotella melaninogenica
Prevotella spp
Fusobacterium nucleatum
Fusobacterium nucleatum
Aeromonas hydrophilia
Aeromonas hydrophilia
Citrobacter freundii, Citrobacter koseri
Citrobacter freundii
Citrobacter koseri
Kingella spp
Kingella spp
Klebsiella pneumoniae
Pseudomonas aeruginosa
Pseudomonas aeruginosa
Pseudomonas spp
Fusobacterium necrophorum
Fusobacterium necrophorum
Brucella spp
Brucella spp
Enterobacter aerogenes, Enterobacter cloacae
Enterobacter aerogenes
Enterobacter cloacae
Klebsiella oxytoca, Klebsiella pneumoniae
Klebsiella oxytoca
Klebsiella pneumoniae
Proteus mirabilis, Proteus vulgaris
Proteus mirabilis
Proteus vulgaris
Capnocytophaga
Capnocytophaga on Chocolate agar
Yersinia enterocolitica
Yersinia enterocolitica
Acinetobacter baumannii complex
Acinetobacter baumannii complex
Salmonella typhimurium
Salmonella typhimurium
Veillonella parvula
Cardiobacterium hominis
Cardiobacterium hominis
Pasteurella multocida (small bacilli or coccobacilli)
Pasteurella multocida
Legionella pneumophila
Legionella pneumophila
Bordetella pertussis
Bordetella pertussis
Actinobacillus spp (small bacilli or coccobacilli)
Actinobacillus spp
Francisella tularensis
Francisella tularensis on Chocolate agar
Plesiomonas
Plesiomonas spp
Vibrio vulnificus
Vibrio parahemolyticus
Vibrio cholerae
Vibrio cholerae on TCBS agar
Morganella morganii
Morganella morgani morganii
Serratia marcescens
Serratia marcescens
Shigella flexneri
Shigella flexneri on Hektoen agar
Burkholderia pseudomallei (showing typical "bipolar" staining, resulting in a "safety pin-like" appearance
Burkholderia pseudomallei
Alcaligenes
Alcaligenes faecalis
Eikenella corrodens: This organism is a fastidious, Gram-negative, facultative anaerobe. This is a pleomorphic GNR that may be variable in shape and size, often appearing as coccobacilli (oval/egg-shaped). Because it colonizes the oral cavity and teeth, it is associated with human bite infections or head and neck wounds. It is also part of the HACEK group of bacteria that is associated with endocarditis.
Pseudomonas fluorescens
Pseudomonas aeruginosa: green metallic sheen, grape-like/fruity scent on blood agar, spreading colonies
Stenotrophomonas maltophilia: This Gram-negative rod is aerobic, a nonfermenter, motile, and grows well on blood agar and MacConkey agar, producing a yellowish pigment on blood agar. It is catalase + and oxidase -. It is linked to nosocomial infections and is able to colonize endotracheal and tracheostomy tubes, indwelling urinary catheters, central venous catheters, prosthetics, and the respiratory tract. Colonizations are on the rise in patients with Cystic Fibrosis (CF). It is a rare cause of bloodstream, urinary tract infections or pneumonia in normally healthy, immunocompetent persons. In immunosuppressed/immunocompromised patients, it may cause more serious pulmonary infections.
Stenotrophomonas maltophilia
Streptobacillus Spp: This is a Gram-negative, facultative anaerobe. It will often grow out and appear microscopically as Gram-negative bacilli in chains. S. moniliformis is associated with infection, particularly rat bite fever. Illness is caused either by a bite, or by close contact with rodents or ingestion of food items or liquids contaminated with rat feces. It is also called Haverhill fever. Additionally, this microbe can cause meningitis, endocarditis, or pneumonitis. Mortality rate is about 10%.
Achromobacter spp
Achromobacter spp
Methylobacterium spp: This ubiquitous GNR is associated with infections in immunocompromised patients. This slow-grower produces a lovely pink-to-coral pigment. It has been linked to outbreaks due to tap water in dental settings, hospital and dialysis settings.
Methylobacterium: coral pigment upon longer incubation time
S. maltophilia: pink colonies
Eikenella corrodens: A defining characteristic is that it "pits" the agar it is growing on. Colonies are small, gray, and have a "bleach-like" or awful odor to them. This organism is catalase -, oxidase +, urease -, indole -. It also reduces nitrate to nitrite.