Emergence of carbapenem resistance in Acinetobacter baumannii in the Czech Republic is associated with the spread of multidrug-resistant strains of European clone II

Abstract

<sec><st>Objectives</st> The aim of this study was to analyse the emergence of carbapenem resistance among hospital strains of <it>Acinetobacter</it> in the Czech Republic. </sec> <sec><st>Methods</st> <it>Acinetobacter</it> isolates were collected prospectively in 2005–06 from 19 diagnostic laboratories. They were identified to species level by AFLP, typed using AFLP, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing, and tested for susceptibility to 14 antimicrobials and for the presence of 20 genes associated with antimicrobial resistance. </sec> <sec><st>Results</st> A total of 150 <it>Acinetobacter</it> isolates were obtained from 56 intensive care units of 20 hospitals in 15 cities. They were identified as <it>Acinetobacter</it> <it>baumannii</it> (<it>n</it> = 108) or other species. <it>A</it>. <it>baumannii</it> isolates were allocated to EU clone I (<it>n</it> = 5), EU clone II (<it>n</it> = 66) or other, mostly unique genotypes. Two-thirds of the clone II isolates had nearly identical AFLP and PFGE fingerprints. As many as 85% and 88% isolates were susceptible to meropenem and imipenem (≤4 mg/L), respectively. Carbapenem MICs of ≥8 mg/L were found in 23 <it>A</it>. <it>baumannii</it> isolates, of which 20 belonged to clone II. Isolates with <it>bla</it><inf>OXA-58-like</inf> (<it>n</it> = 3)<inf>,</inf> <it>bla</it><inf>OXA-24-like</inf> (<it>n</it> = 1) or IS<it>Aba1</it> adjacent to <it>bla</it><inf>OXA-51-like</inf> (<it>n</it> = 34) had carbapenem MICs of 2 to >16 mg/L, while those without these elements showed MICs of ≤0.5–4 mg/L. Clone II isolates varied in susceptibility to some antibiotics including carbapenems and carried 6–12 resistance genes in 17 combinations. </sec> <sec><st>Conclusions</st> The emergence of <it>Acinetobacter</it> carbapenem resistance in the Czech Republic is associated with the spread of <it>A</it>. <it>baumannii</it> strains of EU clone II. The variation in susceptibility in these strains is likely to result from both the horizontal spread of resistance genes and differential expression of intrinsic genes. </sec>