Pasteurella spp

• P. aerogenes
• P. bettyae
• P. caballi
• P. canis
• P. multocida
  • subsp multocida
  • subsp septica
  • subsp gallicida
• P. pneumotropica
• P. stomatitis

Gram Stain

• Gram negative bacilli/cocci small singly or in pairs or short chains (often bipolar staining) (facultative anaerobic)

Clinical Significance

Pasteurella spp. are found in both healthy and diseased animals (wild and domestic). Animals are the reservoir for most human infections.

The genus Pasteurella is undergoing numerous taxonomic changes.

P. aerogenes – part of the oropharyngeal and gastrointestinal flora of pigs.  Rare human infections, usually following traumatic/occupational exposure include wound infection and perinatal infection.

P. bettyae – reservoir for this organism is not known.  It has been recovered from amniotic fluid, urogenital specimens (especially Bartholin’s gland abscesses), and wounds/abscesses.  It has also been associated with bacteremia (especially in neonates).

P. caballi – associated with infections following exposure to horses.

P. canis - associated with dog bite wounds.

P. dagmatis - associated with wounds following bites or animal contact as well as pneumonia, endocarditis, and septicemia.

P. multocida; subsp. multocida, P. multocida subsp. septica, P. multocida subsp. gallicida  - commensal in the oral flora of dogs and cats, other mammals, and fowl.  They are associated with bite wound infections and may cause osteomyelitis, bacteremia, endocarditis, meningitis, brain abscesses, ophthalmic infections, peritonitis, genitourinary infections, pneumonia, lung abscess, and empyema.

P. pneumotropica – part of the upper respiratory tract flora of dogs, cats, mice, and rats. Humans are usually infected by traumatic exposure.  Infections include wound infections, cellulitis, bacteremia, upper respiratory tract infections, and peritonitis.

P. stomatis - associated with bite wounds.

Usual Susceptibility Pattern

These organisms are resistant to 1st generation cephalosporins, clindamycin, and aminoglycosides.

Rare penicillin strains have been described (beta-lactamase production).

They are typically susceptible to amoxicillin-clavulanate, 2nd/3rd generation cephalosporins, quinolones, tetracyclines, and TMP/SMX.

Susceptibility to macrolides is variable (erythromycin always considered resistant).