Molecular Dissection Of Bla(Kpc-2)-Bearing Plasmids Evolving In Klebsiella Pneumoniae Isolated At One Teaching Hospital In Shanghai, China

The presence of carbapenemase gene bla(KPC-2) in a wide variety of plasmids, especially conjugative plasmids, is key to the rapid, worldwide spread of carbapenemase enzymes. Thirty-eight, non-duplicated, carbapenem-resistant, clinical Klebsiella pneumoniae isolates were collected, all carrying bla(KPC-2)-bearing plasmids. Relaxase analysis was used to classify these plasmids; 8 and 30 plasmids belonged to the MOBP3 and MOBF12 subfamilies, respectively. Phylogenetic analysis revealed two genetic subclades in the MOBF12 subfamily and suggested that these subclades might not have originated from the same ancestor. Crossing PCR, used to sequence fully the type IV secretion system (T4SS, essential structures for conjugative plasmids) of the MOBF12 plasmids, found that T4SSs were distinctively different in certain functional genes, e.g. traS and traG. In conclusion, this study delineated the evolution of bla(KPC-2)-bearing plasmids at Huashan Hospital, Shanghai, China. The plasmids bearing bla(KPC-2) were diverse and the MOBF12 plasmids were dominant in clinical K. pneumoniae isolates.