In Vitro Antimicrobial Activities of Meropenem, Ciprofloxacin, Colistin Alone and in Combinations Against Meropenem-Resistant Pseudomonas Aeruginosa

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Katareeya Ek-akaranawakul
Santad Chanprapaph
Pintip Pongpech
Penphun Naenna

Abstract

Determinations of in vitro antimicrobial activities of meropenem, ciprofloxacin, colistin
alone and in combinations against 20 clinical isolates of P. aeruginosa have shown that 16
isolates (80%) were multidrug-resistant (MDR) isolates. All isolates were resistant to meropenem
(MIC90=32 μg/mL) whereas 4 out of 20 isolates (20%) were susceptible to ciprofloxacin
(MIC90=64 μg/mL). Furthermore, all isolates were susceptible to colistin (MIC90=2 μg/mL). With
checkerboard method, it has been shown that meropenem in combination with ciprofloxacin or
colistin and ciprofloxacin in combination with colistin had synergistic effects with drug
concentration within the therapeutic serum level against 3, 6 and 4 isolates, respectively. For
triple combination of meropenem, ciprofloxacin and colistin, the synergistic effect was observed
in 5 isolates. Taken these results into account, meropenem in combination with colistin may be
optimal alternative treatment for meropenem-resistant P. aeruginosa infections.

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Section
2010 Annual Meeting Abstracts/Lectures