COMPARATIVE PROPHYLACTIC EFFICACY OF CEFAZOLIN AND VANCOMYCIN IN A GUINEA-PIG MODEL OF STAPHYLOCOCCUS-AUREUS WOUND-INFECTION

The increasing prevalence of methicillin-resistant Staphylococcus aure us as a wound pathogen in some institutions has prompted the use of va ncomycin for surgical prophylaxis, although clinical data comparing va ncomycin and cephalosporins are not available. A guinea pig model was used to compare the efficacy of vancomycin and cefazolin in preventing intermuscular abscess formation by 7 S. aureus strains. Both antibiot ics were administered to achieve peak serum levels at the time of bact erial inoculation, and each remained > 1 mug/mL for a comparable durat ion. Vancomycin provided equivalent protection from infection by 1 met hicillin-susceptible strain and significantly better protection agains t 4 methicillin-susceptible and both methicillin-resistant S. aureus s trains. For most strains, the bacterial inoculum with a 50% probabilit y of causing an abscess was 2 to 4 log10-fold higher with vancomycin t han cefazolin prophylaxis. Prophylaxis with vancomycin is superior to cefazolin in preventing intermuscular infection by methicillin-suscept ible and -resistant S. aureus.