Molecular characterization of carbapenem-non-susceptible Acinetobacter spp. in Japan: Predominance ofmultidrug-resistant Acinetobacter baumannii clonal complex 92 and IMP-type metallo-β-lactamase-producing non- baumanniiAcinetobacter species

摘要

We conducted an epidemiological study concerning carbapenem-non-susceptible clinical isolates of Acinetobacter spp. inJapan by molecular procedures including carbapenemase gene identification and amplified ribosomal DNA restriction analysis.Among 598 clinically isolated Acinetobacter spp. in 2007, 27 (4.5%) were non-susceptible to carbapenems. Mostcarbapenem-non-susceptible Acinetobacter baumannii (13/14) belonged to clonal complex (CC) 92, harbored bla OXA-51-like genes, including novel bla OXA-206, downstream of ISAba1, and were recovered mainly fromthe Kanto region. Carbapenem-non-susceptible A. baumannii CC92 isolates were further divided by pulsed-field gelelectrophoresis into two groups, one of which was characterized by the presence of bla OXA-23. One A. baumanniiCC276 isolate carried bla IMP-1 and bla OXA-58. Almost all non-baumannii Acinetobacter isolates(12/13), including Acinetobacter pittii (formerly Acinetobacter genomic species 3) and Acinetobacter nosocomialis (formerlyAcinetobacter genomic species 13TU), produced IMP-type metallo-β-lactamases, and were recovered from various regions inJapan. This is the first report describing the nationwide molecular epidemiology of carbapenem-non-susceptible Acinetobacterspp. with genomic species-level identification in Japan.