title: Activity of oxacillin versus that of vancomycin against oxacillin-susceptible mecA-positive Staphylococcus aureus clinical isolates evaluated by population analyses, time-kill assays, and a murine thigh infection model.
abstract: We compared the activity of dicloxacillin with that of vancomycin against 15 oxacillin-susceptible, methicillin-resistant Staphylococcus aureus (OS-MRSA) clinical isolates. By population analyses, we found that 6 OS-MRSA isolates were able to grow in the presence of up to 8 μg/ml dicloxacillin and 9 isolates were able to grow in 12 to >32 μg/ml dicloxacillin; all isolates grew in up to 2 μg/ml vancomycin. Both drugs exhibited similar bactericidal activities. In experimental infections, the therapeutic efficacy of dicloxacillin was significant (P < 0.05 versus untreated controls) in 10 OS-MRSA isolates and vancomycin was effective (P < 0.05) against 12 isolates; dicloxacillin had an efficacy that was comparable to that of vancomycin (P > 0.05) in 8 isolates. The favorable response to dicloxacillin treatment might suggest that antistaphylococcal penicillins could be used against OS-MRSA infections.
authors.affiliation: Department of Microbiology, Medical School, University of Thessaly, Larissa, Greece.
authors.forename: Maria
authors.initials: M
authors.lastname: Labrou
authors.forename: George
authors.initials: G
authors.lastname: Michail
authors.forename: Eleni
authors.initials: E
authors.lastname: Ntokou
authors.forename: Theodore E
authors.initials: TE
authors.lastname: Pittaras
authors.forename: Spyros
authors.initials: S
authors.lastname: Pournaras
authors.forename: Athanassios
authors.initials: A
authors.lastname: Tsakris
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D004009:Dicloxacillin / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D051379:Mice; D008807:Mice, Inbred BALB C; D010068:Oxacillin / Q000494:pharmacology* / Q000627:therapeutic use*; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000472:pathogenicity*; D013848:Thigh / Q000382:microbiology*; D014640:Vancomycin / Q000494:pharmacology* / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin; D004009:Dicloxacillin; D010068:Oxacillin