Virulence and transferability of resistance determinants in a novel Klebsiella pneumoniae sequence type 1137 in China.

A study was designed to characterize three carbapenemase-producing Klebsiella pneumoniae isolated from pediatric patients in China. Molecular characterization was done using polymerase chain reaction and sequencing for blaVIM, blaNDM, blaIMP, blaKPC, blaCTX-Ms, blaOXAs, blaTEMs, and blaSHV; plasmid-mediated quinolone resistance determinants; aminoglycoside resistance determinants; multilocus sequencing typing; plasmid replicon typing; addiction; and virulence factors. Kp32 belonged to the newly described sequence type 1137, were positive for aac(6')-Ib-suzhou, qnrA1, qnrB4, qnrS1, aac(6')-Ib, rmtB, armA, blaSHV-12, blaCTX-M-15, blaKPC-2, and blaIMP-4; contained IncA/C plasmids that tested positive for K1 capsular antigens, the ccdAB (coupled cell division locus) addiction system and the wabG, ureA, rmpA, magA, allS, fimH, and the aerobactin virulence factors. However, the others belonged to clone ST11, and were positive for aac(6')-Ib-cr, qnrB4, blaCTX-M-14, blaSHV-11, aac(6')-Ib, rmtB, and blaKPC-2; contained IncFIA plasmids that tested positive for K2 capsular antigens, the vagCD addiction system and the uge, wabG, ureA, kfuBC, rpmA, and fimH virulence factors. ST1137 had more virulence factors than the comparative strains ST11. The blaKPC-2 gene was located on the IncFIA and IncA/C replicon groups of plasmids. An analysis of the genetic environment of blaKPC-2 gene has demonstrated that the blaKPC-2 gene was always associated with one of the Tn4401 isoforms (a or b). Our study suggested that K. pneumoniae carbapenemases being found in virulent K. pneumoniae should be emphasized, as this will eventually become a global health threat.