Characterization of the blaKPC-2 and blaKPC-3 genes and the novel blaKPC-15 gene in Klebsiella pneumoniae.

Three Klebsiella pneumoniae isolates exhibiting high-level resistance to carbapenem were analysed by PCR, PFGE, gene mapping, plasmid conjugation and Southern blot hybridization using a blaKPC probe. In addition to the frequently reported blaKPC-2 and blaKPC-3 genes, a novel blaKPC-15 gene was identified in one of the isolates. The results of plasmid analysis and Southern blot hybridization revealed that the three blaKPC genes were located on transferable plasmids exhibiting three different patterns. The patterns A, B and C were observed in the genetic makeup of each individual plasmid, and all three structures contained ISKpn6-like and ISKpn8 transposons. The results of the gene mapping and hybridization experiments performed with the blaKPC probe demonstrated that the plasmids harboured the three genes at approximately the 85.0, 54.0 and 73.0 kb positions. The study concluded that carbapenem resistance in the three isolates was primarily due to the production of carbapenem-hydrolysing β-lactamase.