Investigation of synergism of meropenem and ciprofloxacin against Pseudomonas aeruginosa and Acinetobacter strains isolated from intensive care unit infections

Abstract

The aim of this study was to determine synergistic effects of meropenem and ciprofloxacin against Pseudomonas aeruginosa and Acinetobacter strains isolated from intensive care unit (ICU) infections. A total of 18 P. aeruginosa and 17 Acinetobacter strains were tested. MICs were determined using the broth microdilution method. The synergy of meropenem and ciprofloxacin was investigated in glass tubes using time-kill methodology. The synergistic effect of meropenem and ciprofloxacin in combination was found to be 22% at 0.5 x the MIC and 61% at 1 x the MIC in P. aeruginosa strains. Two strains (11%) showed synergy at both 0.5 and 1 x the MIC. Of the 18 P. aeruginosa strains, 1 strain (6%) did not show a synergistic effect at either 0.5 or 1 x the MIC. In Acinetobacter strains, the synergistic effect of meropenem and ciprofloxacin in combination was found to be 29% at 0.5 x the MIC and 18% at 1 x the MIC. One strain (6%) showed synergy at both 0.5 and 1 x the MIC. Of the 17 Acinetobacter strains, 8 strains (47%) did not show a synergistic effect at either 0.5 or 1 x the MIC. According to the results of this study, the combination of meropenem and ciprofloxacin is more effective than either antibiotic alone in ICU infections due to P. aeruginosa strains.