Clonal dissemination of KPC-2 producing Klebsiella pneumoniae ST11 clone with high prevalence of oqxAB and rmtB in a tertiary hospital in China: Results from a 3-year period

Abstract

Background: Carbapenemase-producing Klebsiella pneumoniae (CPKP) strains have emerged as a major problem for healthcare systems. The aim of this study was to determine the circulating clones and analyze the clinical and molecular characteristics of CPKP in our hospital. Methods: A total of 74 carbapenemase producers collected from our hospital from 2012 to 2014 were analyzed for the prevalence of extended-spectrum β-lactamase (ESBLs), plasmid-mediated quinolone resistance genes (PMQRs), exogenously acquired 16S rRNA methyltransferase (16S-RMTase), and plasmid-mediated AmpC enzyme (pAmpCs) by PCR and DNA sequencing. The sequence types (STs) of the carbapenemase producers were analyzed by multi-locus sequence typing (MLST). And Pulsed-field gel electrophoresis (PFGE) was performed to investigate the genetic relationship of KPC-2 producing strains. Clinical data were retrieved from the medical records. Results: KPC-2 (n=72) was the predominant enzyme followed by NDM-1 (n=2); The genes blaCTX-M, blaSHV, blaTEM-1, blaDHA-1, rmtB, armA, oqxA, oqxB, and qnrB were present in 29 (39.2%), 27 (36.5%), 46 (62.2%), 2 (2.7%), 25 (33.8%), 1 (1.4%), 60 (81.1%) and 56 (75.7%), 6 (8.1%) isolates, respectively. MLST analysis revealed 10 different STs. The most dominant ST was ST11 (78.4%, 58/74), followed by ST15 (8.1%, 6/74). PFGE patterns of the KPC-2 producing K. pneumoniae isolates exhibited clonal dissemination of ST11 and ST15 clones as well as a genetic diversity of the remaining strains. Conclusion: The intra- and inter-hospital cross-transmission of KPC-2-producing K. pneumoniae ST11 co-carrying oqxAB and rmtB in our hospital strongly suggested that rapid identification of colonized or infected patients and screening of carriers is quite necessary to prevent a scenario of endemicity.