Reference Tables

Bacterial Organisms by Morphology/Oxygen Requirement [Companion]

Aerobes/Facultatives Anaerobes
Gram-Positive Cocci

  • Streptococcus canis (often in chains)
  • Staphylococcus spp.
  • Enterococcus spp.

Filamentous, branching rods

  • Nocardia spp.


  • Corynebacterium spp.
  • Listeria spp.
  • Mycobacterium

  • Clostridium spp. (incl. difficile and perfringens)

Filamentous, branching rods

  • Actinomyces spp.
Gram-Negative Bacilli (enteric spp.)

  • Escherichia coli
  • Proteus spp.
  • Salmonella enterica, and other spp.
  • Klebsiella spp.
  • Other Enterobacteriaceae
  • Campylobacter jejuni (“seagull wing” appearance)

Bacilli (non-enteric spp.)

  • Pseudomonas aeruginosa
  • Pasteurella¬†spp.
  • Bordetella bronchiseptica
  • Brucella canis (short rods to cocci)
Bacilli (enteric spp)

  • Bacteroides spp.

Bacilli (non-enteric spp)

  • Prevotella spp.
  • Porphiromonas spp.


  • Anaplasma spp.
  • Ehrlichia spp.
  • Neorickettsia spp.
  • Intracellular: Chlamydophila spp. (G- but difficult to Gram stain), Anaplasmataceae family (Anaplasma, Ehrlichia, Neorickettsia)
  • Spirochetes: Leptospira spp., Borrelia burgdorferi
  • Acid fast: Mycobacterium spp., Nocardia spp.
  • Lack a Cell Wall: Mycoplasma spp. (can be intracellular or extracellular)


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