Characterization of the genetic environment of the bla(KPC-2) gene among Klebsiella pneumoniae isolates from a Chinese Hospital

Infection caused by carbapenem-resistant Klebsiella pneumoniae has become a major healthcare threat and KPC-2 enzyme is a dominant factor mediating carbapenems resistance in K. pneumoniae. This study was designed to determine the genetic environment of bla(KPC-2), which prevailed in clinical K. pneumoniae isolates recovered in Huashan Hospital, Shanghai, China. Forty-two clinical isolates were included in this study by bla(KPC-2) screening. After multilocus sequence typing and plasmid analyses of PCR-based replicon typing (PBRT), junction PCR, mapping PCR and crossing PCR assays, primer walking, and amplicon sequencing were used to analyze the genetic environment of the bla(KPC-2) gene. ST423, ST65, ST977, and ST11 were all detected in KPC-2-producing K. pneumoniae. Two types of bla(KPC-2)-bearing genetic structure were found: Tn1721-bla(KPC-2)-Tn3 and Tn1721-bla(KPC-2)-ΔTn3-IS26; and were carried in IncX and IncFII plasmids, respectively. In conclusion, the genetic environment of the bla(KPC-2) gene was diverse and Tn1721-bla(KPC-2)-ΔTn3-IS26 was dominant in clinical K. pneumoniae isolates in Huashan Hospital. This study sheds some light on the genetic environment and should foster further studies about the mechanism of the bla(KPC-2) dissemination.