Gram-Negative Organisms Recovered From Culture

This version of the course is no longer available.
Need multiple seats for your university or lab? Get a quote
The page below is a sample from the LabCE course . Access the complete course and earn ASCLS P.A.C.E.-approved continuing education credits by subscribing online.

Learn more about (online CE course)
Gram-Negative Organisms Recovered From Culture

Oxygen Requirement/Gram Stain CharacteristicsCommon GenusCharacteristic Gram Stain Morphology/Comments
Aerobic, gram-negative cocci (GNC)Neisseria
Moraxella catarrhalis
  • Gram-negative diplococci (pairs) with adjacent sides flattened (coffee bean shaped)
Aerobic, gram-negative rods (GNRs) and coccobacilliPseudomonas
Haemophilus
  • Pseudomonas: Straight, slender, gram-negative rods (GNRs).
  • H. influenzae: Small , pale staining, coccobacilli or short GNRs.
Anaerobic, GNRsBacteroides
Fusobacterium
  • B. fragilis: Pale-staining, pleomorphic rods with rounded ends.
  • F. nucleatum subspecies nucleatum: Pleomorphic GNRs with round to tapered ends.
Facultative anaerobic GNRsEnterics (eg, Escherichia, Klebsiella, Proteus, Enterobacter, Salmonella, Shigella)
  • Typically, the enterics are plump GNRs.
  • There is not a unique morphology that can be used to distinguish between the enteric organisms.