Carbapenem activities against Pseudomonas aeruginosa: respective contributions of OprD and efflux systems.

Antimicrob Agents Chemother

Department of Genetics and Microbiology, Centre Médical Universitaire, Geneva 4, Switzerland.

Published: February 1999

While meropenem MICs were strongly influenced by the presence or absence of the MexAB-OprM efflux pump in both OprD-proficient and -deficient strain backgrounds, MICs of imipenem and of ER-35786 remained unchanged, demonstrating that meropenem is a substrate of MexAB-OprM but not imipenem and ER-35786. In vitro, all three carbapenems selected loss of OprD as a first mechanism of resistance. However, in an OprD-deficient background, meropenem was able to select MexAB-OprM overproducers as a secondary resistance mechanism, while ER-35786 selected a mutant cross-resistant to sparfloxacin and cefpirome.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC89097PMC
http://dx.doi.org/10.1128/AAC.43.2.424DOI Listing

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