Dissemination of an AbaR-type Resistance Island in Multidrug-resistant Acinetobacter baumannii Global Clone 2 in Daejeon of Korea

Background: Acinetobacter baumannii resistance islands (AbaRs) are transposons that have the role of important vehicles for the acquisition of antimicrobial resistance genes, and are associated with multidrug resistance (MDR). In this study, we aimed to determine the AbaRs in MDR A. baumannii global clone 2 (GC2) clinical isolates obtained from a university hospital in Daejeon, Korea. Methods: This study included 17 MDR A. baumannii strains isolated in Daejeon, Korea. The minimal inhibitory concentrations (MICs) were determined by Etest. A. baumannii isolates were characterized using 2 multiplex PCR assays and a multilocus sequence typing (MLST) scheme. To detect and characterize AbaRs, PCR and PCR mapping experiments were performed. Results: All 17 MDR A. baumannii isolates tested in this study belonged to GC2 and contained 5 sequence types (STs): 75, 92, 137, 138, and 357. Tn6166 that contains antimicrobial resistance genes and is also known as AbaR4a was found in all 17 GC2 strains. This is the first report of Tn6166 in MDR A. baumannii GC2 isolates in Korea. In contrast, AbaR4 was not found in the GC2 isolates. Conclusion: Tn6166 has been disseminated among MDR A. baumannii GC2 isolates in Korea. Further investigation is needed to recover the various types of AbaRs in MDR A. baumannii GC2 isolates in Korea are responsible for the multiple antimicrobial resistance mechanisms. (Ann Clin Microbiol 2013;16: 75-80)