In vitro susceptibility of Mycobacterium marinum to dihydromycoplanecin A and ten other antimicrobial agents.

The in vitro susceptibilities of 16 Mycobacterium marinum strains to 11 antimicrobial agents were determined by the Dubos Tween albumin liquid dilution technique. The results (MICs) were: 0.19-0.39 microgram/ml for dihydromycoplanecin A; 0.78-1.56 micrograms/ml for amikacin; 1.56-3.13 micrograms/ml for ofloxacin, norfloxacin and enoxacin; 1.56-6.25 micrograms/ml for minocycline; 1.56-25 micrograms/ml for sulfamethoxazole and sulfamethoxazole-trimethoprim; 3.13-12.5 micrograms/ml for oxytetracycline; 25-200 micrograms/ml for trimethoprim; and 50-200 micrograms/ml for pipemidic acid. The most active drugs were dihydromycoplanecine A and amikacin. Also active were minocycline, oxytetracycline, sulfamethoxazole and sulfamethoxazole-trimethoprim. Ofloxacin, norfloxacin and enoxacin demonstrated activity only at concentrations at or greater than those usually attained in serum. Pipemidic acid and trimethoprim were inactive.