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 β-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.

To investigate the prevalence of bla_NDM-1 in Gram-negative bacilli in China. A total of 11 298 clinical Gram-negative bacilli, covering Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa, were collected for PCR-based surveillance of bla_NDM-1 from 57 hospitals representing 18 provinces in China. For bla_NDM-1-positive isolates, antibiotic susceptibilities were assessed and molecular typing was performed using PFGE. The genetic location of bla_NDM-1 was determined by analysis of PFGE profiles of S1 nuclease-digested genomic DNA and Southern blot hybridization. Plasmid transfer to E. coli recipients was investigated using filter mating and electroporation. Four A. baumannii isolates with bla_NDM-1 were identified in four different provinces in China: no positive isolates were detected among E. coli, K. pneumoniae and P. aeruginosa. These bla_NDM-1-positive A. baumannii were resistant to all carbapenems and cephalosporins, and three remained susceptible to fluoroquinolones, aminoglycosides and colistin. The four NDM-1-producing A. baumannii were clonally diverse and carried bla_NDM-1 on different plasmids. Plasmids carrying bla_NDM-1 were successfully transferred from three of the four isolates to E. coli recipients, although the transconjugants and transformants were prone to lose the transferred plasmids after passage in the absence of ampicillin selection. We describe the emergence of A. baumannii producing NDM-1 in China. Systemic surveillance network should be established for monitoring these resistant bacteria.

A carbapenem-resistant isolate of Klebsiella pneumoniae producing class A carbapenemase KPC-2 was identified in Zhejiang, China. The KPC-2 gene was located on an approximately 60-kb plasmid in a genetic environment partially different from that of bla _KPC-2 in the isolates from the United States and Colombia.

Thirty-nine bla _KPC -producing isolates of the family Enterobacteriaceae with carbapenem resistance or reduced carbapenem susceptibility were obtained from inpatients from eight hospitals in six cities of three provinces in eastern China. The pulsed-field gel electrophoresis analysis of all 36 Klebsiella pneumoniae isolates revealed six major patterns. The resistant plasmids of most isolates were successfully transferred by conjugation and evaluated experimentally to be 40 to 180 kb in size. A 20.2-kb bla _KPC -surrounding nucleotide sequence from plasmid pKP048 has been obtained and contains an integration structure of a Tn 3 -based transposon and partial Tn 4401 segment, with the gene order Tn 3 -transposase, Tn 3 -resolvase, IS Kpn8 , the bla _KPC-2 gene, and the IS Kpn6 -like element. The chimera of several transposon-associated elements indicated a novel genetic environment of the K. pneumoniae carbapenemase β-lactamase gene in isolates from China.