Antimicrobial Susceptibility of Gram-Negative Bacilli Isolated in Brazilian Hospitals Participating in the SENTRY Program (2003-2008)

Abstract

We report the antimicrobial susceptibility patterns of the five most frequently isolated Gram-negative bacilli in the Brazilian hospitals participating in the SENTRY Program. A total of 3,220 Gram-negative bacilli were analyzed. The strains were consecutively collected (one per patient) between January 2003 and May 2008 and susceptibility tested by reference broth microdilution methods at the JMI Laboratories (North Liberty, Iowa, USA). The Gram-negative organisms most frequently isolated from bloodstream infections were Escherichia coli (12.8% of total), Klebsiella spp.(12.5%), Pseudomonas aeruginosa (9.6%), Acinetobacter spp. (8.0%) and Enterobacter spp. (6.4%). P aeruginosa ranked first (36.3% of cases) among organisms isolated from patients with pneumonia and second (15.1%) among organisms isolated from skin and soft tissue infections. Approximately 10% of E. coli and 50% of K. pneumoniae exhibited an ESBL phenotype. The carbapenems imipenem and meropenem were very active against Enterobacteriaceae strains, including E. coli and K. pneumoniae with ESBL phenotype and cefepime-non-susceptible Enterobacter spp., while ertapenem and polymyxin B showed more limited activity against Enterobacter spp. P. aeruginosa and Acinetobacter spp. showed high rates of resistance to all compounds tested except polymyxin B (99.4-99.9% susceptible). No antimicrobial agent alone provided appropriate coverage for the Gram-negative bacilli most frequently isolated in the hospitals participating in the SENTRY Program; thus, empiric therapy for serious infections may require a carbapenem (imipenem or meropenem) plus a polymyxin (polymyxin B or colistin).