Contemporary in vitro spectrum of activity summary for antimicrobial agents tested against 18569 strains non-fermentative Gram-negative bacilli isolated in the SENTRY Antimicrobial Surveillance Program (1997-2001).

The frequency of occurrence and antimicrobial susceptibility patterns of 18569 non-fermentative Gram-negative bacilli consecutively collected as part of the SENTRY Antimicrobial Surveillance Program were summarized. The isolates were tested by the broth microdilution method in three coordinator laboratories using common reagents and reference methodologies. The most frequently isolated pathogen was Pseudomonas aeruginosa (11968 isolates; 64.5%) followed by Acinetobacter spp. (3468 isolates; 18.7%) and Stenotrophomonas maltophilia (1488 isolates; 8.0%). The lowest resistance rates for P. aeruginosa documented were for amikacin (8%), meropenem (10%) and cefepime (10%), and all fluoroquinolones tested showed similar resistance rates (22-24%). The most active compounds against Acinetobacter spp. were the carbapenems, imipenem (11% resistance) and meropenem (12% resistance) followed by cefepime (31% resistance) and gatifloxacin (32% resistance). Very few compounds showed reasonable in vitro activity against S. maltophilia, with the most active antimicrobial agents being trimethoprim/sulphamethoxazole, gatifloxacin and levofloxacin (5-6% resistance). Resistance surveillance among these organisms remains necessary to guide empirical antimicrobial therapy, especially for these less frequently isolated and difficult to test pathogens.