PEARLS 34, November 2007, written by Brian R McAvoy

Clinical question
Do prophylactic antibiotics for mammalian bites prevent wound infection?

Bottom line
Prophylactic antibiotics may reduce the rate of infection after bites by humans (NNT* 2, based on 1 study) and after animal bites on the hand (NNT 3 to 7, based on 3 studies). Bites on the head and trunk did not seem to benefit from antibiotics.
There is no evidence that the use of prophylactic antibiotics is effective for cat or dog bites, other than on the hand.
* NNT = number needed to treat to benefit one individual.

Caveat
Several studies included in the review were small, one involving only 12 patients. Different antibiotics were used in the studies, ranging from penicillin V to dicloxacillin.

Context
Bites by mammals are a common problem, accounting for up to 1 per cent of all visits to hospital emergency rooms. Dog and cat bites are the most common, and school-age children comprise almost half of those bitten.

Cochrane Systematic Review
Medeiros I, Saconato H. Antibiotic prophylaxis for mammalian bites. Cochrane Database of Systematic reviews 2001, Issue 2. Article No. CD001738. DOI: 10.1002/14651858.CD001738. Note: This review contains 8 studies with a total of 522 participants.