Prophylactic antibiotics and dog bite wounds

Staphylococcus intermedius: clinical presentation of a new human dog bite pathogen

Staphylococcus intermedius is a Gram-positive, coagulase-positive coccus that can be distinguished from Staphylococcus aureus by routine microbiological testing. Whereas S intermedius is recognized as flora and pathogen of dogs, it has never been isolated from human infections. We hypothesized that S intermedius may cause human dog bite wound infections and that it has been previously misidentified as S aureus. Fourteen isolates from clinically infected dog bite wounds that were originally identified as S aureus were subjected to further testing; three (22%) were found to be S intermedius. The clinical and microbiological characteristics of these three S intermedius cases are described. All three patients were nonimmunocompromised persons seen within 24 hours for bites on the upper extremity. All patients developed cellulitis within one to three days. All S intermedius isolates were distinguished from S aureus by the lack of acetoin production and by the presence of beta-galactosidase activity. S intermedius was susceptible to a wide range of antibiotics; one isolate was resistant to penicillin. Two patients were treated with penicillin, one with amoxicillin-clavulanate, and all were clinically cured. These are the first three reported human infections involving S intermedius. Further study is necessary to define its clinical importance as a potential human pathogen.

A clinical trial using co-trimoxazole in an attempt to reduce wound infection rates in dog bite wounds

One hundred and thirteen patients were entered into a randomized, prospective double-blind, placebo controlled trial to assess the use of co-trimoxazole in reducing wound infections after dog bites. Although there was a reduction in the wound infection rate from 13.8% in the placebo group to 5.5% in the treatment group this did not reach statistical significance (P = 0.135). If hand wounds are considered separately, no infections occurred in the treatment group and a benefit seems likely.