Antimicrobial susceptibilities of unique Stenotrophomonas maltophilia clinical strains

Susceptibility to 41 antimicrobials was studied with 99 Stenotrophomonas maltophilia strains, and different pulsed-field gel electrophoresis profiles were identified among 130 prospectively collected isolates. Moxalactam, doxycycline, minocycline, and clinafloxacin displayed the highest activity (greater than or equal to 98% susceptibility). Ticarcillin resistance (75%) was reverted by clavulanate in 258 of strains. Trimethoprim-sulfamethoxazole resistance was 26.2% (greater than or equal to4 [trimethoprim]/76 [sulfamethoxazole] mug/ml) and dropped to 11.1% when an 8/152-mug/ml breakpoint was applied based on its bimodal MIC distribution. Resistance was lower when unique strains were considered, because clonal organisms contribute to resistance.