ABSTRACT
BACKGROUND: The aim of the present study was to determine the frequency of six efflux pump genes in Acinetobacter clinical isolates collected from South Korean hospitals. METHODS: In this study, we used a total of 339 Acinetobacter strains, comprising 279 Acinetobacter calcoaceticus–Acinetobacter baumannii (ACB) complex and 60 non-ACB complex strains. We performed specific PCR assays to detect adeG, adeB, adeE, adeY, abeM, and adeJ, transporter genes of the multidrug efflux pumps AdeFGH, AdeABC, AdeDE, AdeXYZ, AbeM, and AdeIJK, respectively. RESULTS: Frequencies of six efflux pump genes varied according to the species of Acinetobacter. Frequencies of adeE, abeM, and adeJ between A. baumannii group and A. nosocomialis group were found to be significantly different. Significant differences were found in the frequencies of adeB, adeE, adeY, and adeJ among the susceptible A. baumannii (SAB), multidrug-resistant A. baumannii (MDRAB), and extensively drug-resistant A. baumannii (XDRAB) groups within the 154 strains of A. baumannii. The frequencies of efflux pump genes in imipenem-susceptible and imipenem-nonsusceptible groups were significantly different for adeB, adeY, and adeJ. The frequencies of efflux pump genes in ciprofloxacin-susceptible and ciprofloxacin-nonsusceptible groups were significantly different for adeB and adeY. No significant difference was found in the frequency of efflux pump genes among groups sampled from different regions of Korea, across 86 strains of A. baumannii collected in 2012. CONCLUSIONS: The frequencies of six efflux pump genes obtained in this study demonstrate the fundamental epidemiological feature of efflux pump genes in Korean Acinetobacter clinical isolates.