Antimicrobial susceptibility patterns of unusual nonfermentative gram-negative bacilli isolated from Latin America: report from the SENTRY Antimicrobial Surveillance Program (1997-2002)

ABSTRACT

The antimicrobial susceptibility of 176 unusual non-fermentative gram-negative bacilli (NF-GNB) collected from Latin America region through the SENTRY Program between 1997 and 2002 was evaluated by broth microdilution according to the National Committee for Clinical Laboratory Standards (NCCLS) recommendations. Nearly 74 percent of the NF-BGN belonged to the following genera/species: Burkholderia spp. (83), Achromobacter spp. (25), Ralstonia pickettii (16), Alcaligenes spp. (12), and Cryseobacterium spp. (12). Generally, trimethoprim/sulfamethoxazole (MIC50, < 0.5 æg/ml) was the most potent drug followed by levofloxacin (MIC50, 0.5 æg/ml), and gatifloxacin (MIC50, 1 æg/ml). The highest susceptibility rates were observed for levofloxacin (78.3 percent), gatifloxacin (75.6 percent), and meropenem (72.6 percent). Ceftazidime (MIC50, 4 æg/ml; 83.1 percent susceptible) was the most active beta-lactam against B. cepacia. Against Achromobacter spp. isolates, meropenem (MIC50, 0.25 æg/ml; 88 percent susceptible) was more active than imipenem (MIC50, 2 æg/ml). Cefepime (MIC50, 2 æg/ml; 81.3 percent susceptible), and imipenem (MIC50, 2 æg/ml; 81.3 percent susceptible) were more active than ceftazidime (MIC50, >16 æg/ml; 18.8 percent susceptible) and meropenem (MIC50, 8 æg/ml; 50 percent susceptible) against Ralstonia pickettii. Since selection of the most appropriate antimicrobial agents for testing and reporting has not been established by the NCCLS for many of NF-GNB species, results from large multicenter studies may help to guide the best empiric therapy.