Activity of Oxacillin versus That of Vancomycin against Oxacillin-Susceptible mecA-Positive Staphylococcus aureus Clinical Isolates Evaluated by Population …

M Labrou, G Michail, E Ntokou, TE Pittaras… - Antimicrobial agents …, 2012 - Am Soc Microbiol
Antimicrobial agents and chemotherapy, 2012Am Soc Microbiol
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 …
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.
American Society for Microbiology