ST11, the dominant clone of KPC-producing Klebsiella pneumoniae in China

Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae has spread rapidly in China. In this study, we aimed to investigate the molecular epidemiology of KPC-producing K. pneumoniae isolates in China. Ninety-five carbapenem-resistant K. pneumoniae isolates from 13 hospitals in nine cities covering five provinces in China were analysed. Antibiotic susceptibility was determined by the Etest. Multilocus sequence typing (MLST) and PFGE were used for epidemiological analysis. The genetic structure around bla(KPC) and the encoding genes of extended-spectrum beta-lactamases and plasmid-mediated AmpC enzymes were detected by PCR and sequencing. Plasmids were analysed by transformation, restriction and Southern blot. All isolates harboured the bla(KPC-2) gene. Seven sequence types (STs) were obtained. The dominant clone was ST11 (61/95), which was identified in isolates from Zhejiang province (four hospitals in Hangzhou and one hospital in Ningbo), Jiangsu province (one hospital in Nanjing) and Anhui province (one hospital in Hefei). Isolates with ST11 showed > 80% similarity in PFGE patterns. Plasmids from 14 selected transformants, their original isolates representing different STs and/or regions, had a diversity of HindIII restriction maps. The dominant clone of KPC-producing K. pneumoniae in China is ST11, which is closely related to ST258, which has been reported worldwide.