LAUSR

Introduction Carbapenem-resistant Klebsiella pneumoniae (CRKP) has been widespread in coastal cities of eastern China since 2009. However, how CRKP spreads and evolves in southwest China is unclear. Aim We investigated the genetic characteristics and dissemination mechanisms of carbapenemase genes in forty-one non-repetitive CRKP isolates collected from a southwest hospital, Kunming, Yunnan, during 2010–2013. Methodology Drug susceptibilities were analyzed by using VITEK 2 compact system. Genetic relationships were ascertained based on multilocus sequence typing (MLST) and Pulsed-field gel electrophoresis (PFGE) analysis. Genetic backgrounds of blaKPC-2 and blaNDM-1 were revealed by DNA walking and high-throughput sequencing. Results All isolates were highly resistant to common antibiotics except for tigecycline. In total, 34 blaKPC-2, 3 blaNDM-1, 1 blaIMP-4 and 3 blaIMP-26 genes were identified and KP67 plasmid 1 co-harbored blaNDM-1 and blaIMP-26. Five sequence types, namely ST11, ST290, ST340, ST395 and ST437, were recognized by MLST. Surprisingly, blaKPC-2 was only detected in ST11 strains. We described a clonal dissemination of fosA3-positive IncR-IncF33:A-:B- multireplicon plasmid carrying the gene cassettes IS26-ΔTn3-ISKpn27-blaKPC-2-ΔISKpn6-korC-klcA-ΔrepB-Tn1721 in all ST11 isolates. Three blaNDM-1 positive isolates belonged to three different ST types and their blaNDM-1 genetic backgrounds were also distinct. Interestingly, the flanking regions of blaNDM-1 in KP67 and KP72 were duplicated into one to five copies in a form of tandem repeat by the transposition of IS91 like element. The blaNDM-1 of KP82 was carried on a common IncX3 plasmid. Conclusion This study described the early epidemiological characteristics of blaKPC-2/blaNDM-1-carrying CRKP, and reported a new tandem repeat pattern of blaNDM-1 cluster in Yunnan. These findings extend our knowledge on the carbapenemase gene evolutions.