Animal Bite-associated Infections

Microbiology and Treatment

Nicole Thomas; Itzhak Brook

Disclosures

Expert Rev Anti Infect Ther. 2011;9(2):215-226. 

In This Article

Reptile Bites

Bites from crocodiles or alligators are usually fatal. If the victim survives, there is a high risk of infection. There are reports of infections with Burkholderia pseudomallei, which are usually due to contamination from the environment.[73,74] Multiple microorganisms, especially aerobic Gram negatives, have been isolated from wounds after alligator attacks. A study of the oral flora of alligators showed Aeromonas (most common), Proteus, Pseudomonas and Citrobacter species to be the predominant aerobic isolates. Anaerobic flora were variable with the most common species being Clostridium, Bacteroides, Fusobacterium and Peptococcus.[75,36]

In light of these identified organisms, it is believed that the flora of the crocodile/alligator mouth might actually consist of the flora of the feces of the previous prey.[75] Owing to the high risk of polymicrobial infection in survivors, broad-spectrum empiric antibiotics are recommended (see Table 1).

Both elapids (coral snakes) and crotalids (vipers, rattlesnakes, copperheads) have venom that elicit antimicrobial activity.[76] Elapid bites rarely become infected; however, infection after envenomation by those from the crotalids have been due to a range of organisms, including S. aureus and E. coli.[77,78] Shek, who studied the oral floral of the Chinese cobra, found over 50 species of bacteria, including Morganella, Aeromonas, Proteus and Clostridia species, in addition to S. aureus, Enterococcus and coagulase-negative Staphylococci.[79] Similar to the alligator, it is believed that the flora is fecal in origin, as the live prey may defecate in the snake's mouth as it is being ingested.[80]

The use of prophylactic antibiotics after snakebite is controversial, and generally not recommended.[81–85] Shek et al. however, recommended broad empiric therapy (with levofloxacin and amoxicillin/clavulanate), especially if there is evidence of wound necrosis.[79]Salmonella species are a common pathogen associated with lizard contact. Most lizards generally do not bite, but there are a few reports of infection after bites, ranging from cellulitis with S. marcesens after an iguana bite,[86,87] to septic arthritis due to Pseudomonas aeruginosa after injury from a monitor lizard.[88]

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