Antibacterial activity of norfloxacin on methicillin-resistant staphylococcus aureus

Minimum inhibitory concentrations (MIC) of norfloxacin (NFLX) to 133 strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated from clinical patients were investigated and compared with those of minocycline (MINO), erythromycin (EM), amoxicillin (AMPC), cefaclor (CCL) and fosfomycin (FOM). MIC₉₀ of these drugs were 3.13 μg/ml with NFLX, 0.39 μg/ml with MINO, >100 μg/ml with EM, 50 μg/ml with AMPC, >100 μg/ml with CCL and >100 μg/ml with FOM. MIC distribution patterns with 2 peaks were recognized with EM and FOM. Of 55 strains resistant to all of EM, AMPC, CCL and FOM, 50 and 54 strains were well susceptible to NFLX and MINO, respectively. The present investigation demonstrated relatively potent antibiotic effect of NFLX against MRSA. Considering the safety of NFLX to children which have been confirmed and reported separately, it can be concluded that NFLX is a useful oral antimicrobial drug in the treatment of children with MRSA infections.