Animal Bite-associated Infections

Microbiology and Treatment

Nicole Thomas; Itzhak Brook


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

In This Article

Bear Bites

As the remote bear habitat is encroached by human development, there has been an increase in bear encounters, with a resultant increase in attacks. The oral flora of bears generally reflects their diet, which is high in plant matter, and occasional meat or carrion.[66] Organisms that have been most commonly isolated from the oral cavities of black bears include Streptococcus spp., Staphylococcus spp., E. coli and Enterobacter spp.[67–69] With regards to actual wound infections from bear bites, there are few reports. Kunimoto et al. reported on a hunter who, among other injuries, was bitten on the head by a grizzly bear. The patient was originally given empiric antibiotics (cefazolin and metronidazole), and cultures were obtained 12 h after the attack, but there was still polymicrobial growth, including Serratia spp., Aeromonas hydrophila, Bacillus cereus and Enterococcus spp. No anaerobes were identified.[70] Another case report of bear bite wound infection was reported in a man who sustained several bites from a brown bear. The infected thigh wound grew Mycobacterium fortuitum as well as Streptococcus sanguis, Neisseria sicca and Bacillus spp.[71] Liu et al. reported on a 4-year-old who developed a chronic osteomyelitis after being bitten by a bear in captivity. The wound grew Prevotella oralis, Streptococcus viridans and Propionibacteria acnes.[72] Although there are no specific recommendations regarding empiric therapy after bear bite, Floyd et al. recommended coverage for Gram positives with either a PCN or first-generation cephalosporin, and further modification based on culture results.[67] However, based on the few case reports of actual bear bite infection, it would seem reasonable to also include broader coverage for Gram-negative organisms.


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