Epidemic Plasmid Carrying bla (CTX-M-15) in Klebsiella penumoniae in China

OBJECTIVE: To investigate the local epidemiology of Klebsiella penumoniae carrying bla (CTX-M-15) in southern China and to characterize the genetic environment of bla (CTX-M-15). METHODS: PCR and DNA sequencing were used to detect and characterize the genetic contexts of bla (CTX-M-15). The clonal relatedness of isolates carrying bla (CTX-M-15) was determined by pulse-field gel electrophoresis. Conjugative plasmids carrying bla (CTX-M-15) were obtained by mating and were further subject to restriction analysis and replicon typing. RESULTS: A total of 47CTX-M-15 ESBL-producing isolates of K. pneumoniae were collected from nine hospitals in China from October 2007 to October 2008. Isolates were clustered into various clonal groups. The local spread of bla (CTX-M-15) was mainly mediated by one major conjugative plasmid as determined by S1-PFGE and restriction analysis. A 90-kb plasmid belonging to incompatible group FII was the major carrier of bla (CTX-M-15) in K. pneumoniae. Except bla (TEM-1), the resistance genes such as bla (SHV), bla (DHA-1), bla (OXA-1), qnrB, qnrS, aac(3)-II, and aac(6′)-Ib were not found in the plasmid. In the comparing of conjugative gene sequence, it is 100% identical with the plasmid pKF3–94, which was found in K. pneumonia from Zhejiang province of china previously. CONCLUSIONS: bla (CTX-M-15) was prevalent in K. pneumonia of southern China. The dissemination of bla (CTX-M-15) appeared to be due to the horizontal transfer of a 90-kb epidemic plasmid.