Comparative activity of the topical quinolone OPC-7251 against bacteria associated with acne vulgaris.

The antibacterial activity of the topical quinolone OPC-7251 against bacteria commonly found in acne vulgaris was tested in vitro by an agar dilution method. The MIC50 was 0.25 mg/l for Propionibacterium acnes, 0.125 mg/l for Propionibacterium granulosum, 0.03 mg/l for Staphylococcus aureus and 0.06 mg/l for coagulase-negative staphylococci. Compared with seven other antibiotics tested (ciprofloxacin, penicillin, erythromycin, tetracycline, clindamycin, fusidic acid and gentamicin), OPC-7251 had potent activity against both propionibacteria and staphylococci and the lowest incidence of resistant strains.