In vitro activity of 11 antimicrobial agents, including gatifloxacin and GAR936, tested against clinical isolates of Mycobacterium marinum.

In vitro activities of 11 antimicrobial agents were determined using Etest (AB BIODISK, Solna, Sweden) against 37 clinical isolates of Mycobacterium marinum. The most potent agent (MIC(50,) 0.047 microg/mL) was trimethoprim/sulfamethoxazole, but only 91.9% would be categorized as susceptible. Several agents had a complete spectrum of activity including gatifloxacin (MIC(90,) 0.38 microg/mL), minocycline (MIC(90,) 2 microg/mL), tetracycline (MIC(90,) 2 microg/mL) and amikacin (MIC(90,) 3 microg/mL). The new glycylcycline, GAR936, had a similar potency (MIC(90,) 3 microg/mL) to that of the parent minocycline compound (MIC(90,) 2 microg/mL), but the range of MIC values extended to 24 microg/mL. Numerous options appear to exist for the contemporary therapy of M. marinum infections including some newer fluoroquinolones and derivatives of tetracycline (doxycycline, minocycline, GAR936).