Distribution and Molecular Characterization of Acinetobacter baumannii International Clone II Lineage in Japan.

Multidrug-resistant (MDR) spp. have been globally disseminated in association with the successful clonal lineage international clone II (IC II). Because the prevalence of MDR spp. in Japan remains very low, we characterized all spp. ( = 866) from 76 hospitals between October 2012 and March 2013 to describe the entire molecular epidemiology of spp. The most prevalent species was ( = 645; 74.5%), with IC II ( = 245) accounting for 28.3% of the total. Meropenem-resistant isolates accounted for 2.0% ( = 17) and carried IS ( = 10), ( = 4), or IS ( = 3). Multilocus sequence typing of 110 representative isolates revealed the considerable prevalence of domestic sequence types (STs). IC II isolates were divided into the domestic sequence type 469 (ST469) ( = 18) and the globally disseminated STs ST208 ( = 14) and ST219 ( = 4). ST469 isolates were susceptible to more antimicrobial agents, while ST208 and ST219 overproduced the intrinsic AmpC β-lactamase. IC II and some non-IC II STs (e.g., ST149 and ST246) were associated with fluoroquinolone resistance. This study revealed that carbapenem-susceptible IC II was moderately disseminated in Japan. The low prevalence of acquired carbapenemase genes and presence of domestic STs could contribute to the low prevalence of MDR A similar epidemiology might have appeared before the global dissemination of MDR epidemic lineages. In addition, fluoroquinolone resistance associated with IC II may provide insight into the significance of epidemic clones.