Effectiveness of cefamandole against methicillin-resistant strains of Staphylococcus aureus in vitro and in experimental infections.
An investigation was carried out into the effectiveness of cefamandole as compared to that of cephalothin against methicillin-sensitive and methicillin-resistant strains of Staphylococcus aureus both in vitro and in mice with the experimental peritonitis-induced septicaemia as a model for a generalized infection. In the agar-diffusion test 95% of 118 and in the broth-dilution test 80% of 30 methicillin-resistant strains were sensitive to cefamandole. In experimental infections the ED50 with methicillin-resistant strains was 20 times greater than that required for the methicillin-sensitive strain although the MIC was only twice that for the latter. Doses of cephalothin required for treatment of infections due to methicillin-resistant strains were also twenty times greater than for those due to the methicillin-sensitive strain. But these differences were consistent with those in MIC (by factors of 16-32). Thus, the results of in-vitro testing of cefamandole are not predictive for its therapeutic efficacy in staphylococcal infections with methicillin-resistant strains. Therefore, rather than relying on inhibition zone diameter and MIC, the information that a staphylococcal strain is methicillin-resistant should be used as an indication not to choose cefamandole for chemotherapy.
D000818:Animals; D002435:Cefamandole / Q000097:blood / Q000627:therapeutic use*; D008297:Male; D008712:Methicillin / Q000097:blood / Q000627:therapeutic use; D051379:Mice; D008826:Microbial Sensitivity Tests; D010068:Oxacillin / Q000494:pharmacology; D010403:Penicillin Resistance; D010538:Peritonitis / Q000188:drug therapy; D013203:Staphylococcal Infections / Q000188:drug therapy*; D013211:Staphylococcus aureus / Q000187:drug effects*
D002435:Cefamandole; D008712:Methicillin; D010068:Oxacillin