Organisms of the genus Pasteurella are Gram-negative, non-motile, facultatively anaerobic coccobacilli. Unlike most of the pleomorphic organisms we have spoken of, Pasteurella is not an intracellular parasite. P. multocida is the species which most commonly infects humans. Although most members infect animals, humans can acquire the organism from dog or cat bites. Patients tend to exhibit swelling, cellulitis, and some bloody drainage at the wound site. Infection may also move to nearby joints where it can cause swelling and arthritis (not to mention a lot of pain). Fortunately, P. multocida is susceptble to penicillin, tetracicline, and chloramphenicol. For identification, this organism can be cultured on chocolate agar and can produce a really foul odor.
