Novel Genetic Environment of the Carbapenem-Hydrolyzing β-Lactamase KPC-2 among Enterobacteriaceae in China

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 Tn3-based transposon and partial Tn4401 segment, with the gene order Tn3-transposase, Tn3-resolvase, ISKpn8, the bla(KPC)-2 gene, and the ISKpn6-like element. The chimera of several transposon-associated elements indicated a novel genetic environment of the K. pneumoniae carbapenemase beta-lactamase gene in isolates from China.