Tandem Repeat of blaNDM-1 and Clonal Dissemination of a fosA3 and blaKPC-2 Co-Carrying IncR-F33: A–: B– Plasmid in Klebsiella pneumoniae Isolates Collected in a Southwest Hospital in China, 2010–2013.

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 bla_KPC-2 and bla_NDM-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 bla_KPC-2, 3 bla_NDM-1, 1 bla_IMP-4 and 3 bla_IMP-26 genes were identified and KP67 plasmid 1 co-harbored bla_NDM-1 and bla_IMP-26. Five sequence types, namely ST11, ST290, ST340, ST395 and ST437, were recognized by MLST. Surprisingly, bla_KPC-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 IS 26-ΔTn 3-ISKpn27-bla_KPC-2-ΔISKpn6-korC-klcA-ΔrepB-Tn 1721 in all ST11 isolates. Three bla_NDM-1 positive isolates belonged to three different ST types and their bla_NDM-1 genetic backgrounds were also distinct. Interestingly, the flanking regions of bla_NDM-1 in KP67 and KP72 were duplicated into one to five copies in a form of tandem repeat by the transposition of IS 91 like element. The bla_NDM-1 of KP82 was carried on a common IncX3 plasmid. Conclusion: This study described the early epidemiological characteristics of bla_KPC-2/bla_NDM-1-carrying CRKP, and reported a new tandem repeat pattern of bla_NDM-1 cluster in Yunnan. These findings extend our knowledge on the carbapenemase gene evolutions. [ABSTRACT FROM AUTHOR]