Investigation of the in-vitro effectiveness of ertapenem against Pseudomonas aeruginosa strains isolated from intensive care unit patients

Pseudomonas aeruginosa is one of the important cause of infections in intensive care unit (ICU) patients. The aim of this study was to investigate the effectiveness of ertapenem prior to its use in Turkey, against multiple-resistant P. aeruginosa strains isolated from ICUs. Susceptibility tests were performed by using Kirby-Bauer disk diffusion method and MicroScan MERCH MIC 8 panel (MicroScan 96, Dade Behring, USA). While the resistance rates of ertapenem, imipenem and meropenem were 59.2%, 50% and 48.1% by disk diffusion method, they were 57.4%, 46.2% and 42.5% by MicroScan, respectively. Ertapenem was found less effective against multiple-resistant P. aeruginosa isolates by both of the methods when compared with imipenem and meropenem. Piperacillin/tazobactam was detected as the most effective agent against these isolates by both of the methods. As a result, although carbapenems are frequently used for infections caused by P. aeruginosa, ertapenem, which is a new carbapenem, is not effective as much as the others. In case of confirmation of our results by larger scale studies, the empiric treatment of ICU infections caused by P. aeruginosa with ertapenem, should be carefully evaluated.