Gram negative bacteria

Cocci

1. Neisseria
   1. meningitidis (meningococcus)
   2. gonorrhoeae (gonococcus)
2. Moraxella

Rods (Bacilli)

Lactose Fermenters	Indole	morphology
E. Coli	+	flat
Klebsiella	-	muccoid
Enterobacter	-	muccoid
Citrobacter	-	flat
Arizona	-

Non-Lactose Fermenters	Characteristics
Pseudomonas	usually strict aerobes, oxidase +, small
Salmonella, Shigella
Acinetobacter	coccobac
Proteus	swarming
H. Flu	tiny, chocolate agar
Pasteurella

Interpretations of Key Phrases

• “Gram negative coccobacilli” may suggest Haemophilus species
• “Lactose-positive gram negative rods” may suggest Enterobacteriaceae, such as E. coli, Klebsiella, or Enterobacter spp
• “Lactose-negative gram negative rods” may suggest Pseudomonas

See Also

• Microbiology (Main)