The first report of a novel IncHI1B bla(SIM-1)-carrying megaplasmid pSIM-1-BJ01 from a clinical Klebsiella pneumoniae isolate

Background: A rare member of metallo-β-lactamases genes, bla(SIM-1), carried by a 316-kb plasmid designated pSIM-1-BJ01 was isolated from a clinical cephalosporins- and carbapenem-resistant Klebsiella pneumoniae 13624. This is the first sequence report of a transferable bla(SIM-1)-carrying conjugative plasmid isolated from K. pneumoniae. Purpose: The sequence analysis of pSIM-1-BJ01 will help us to identify genes responsible for conjugation, plasmid maintenance and drug resistance, to understand the evolution and control the dissemination of resistance plasmids. Patients and methods: K. pneumoniae 13624 was isolated from the urine specimen of a patient. Bacterial genomic DNA was sequenced with PacBio RSII platform. Results: Most of the pSIM-1-BJ01 backbone matches that of pRJA166a, which was isolated from a clinical hypervirulent K. pneumoniae ST23 strain at Shanghai, China, recently. The highly homologous backbones between the two plasmids imply the close relationship of evolution. Two different multidrug-resistant regions both carrying the class 1 integrons with different resistance genes have been assembled into the pSIM-1-BJ01. Besides, the other two resistance plasmids, pKP13624-1 carrying bla(TEM-1) and bla(CTX-M-15) and pKP13624-2 carrying bla(CTX-M-14) and bla(LAP-2) were also identified. Conclusion: The emergence of the bla(SIM-1)-carrying IncHI1B pSIM-1-BJ01 suggests the spread of bla(SIM) among Enterobacteriaceae is possible. We should pay more attention to supervise and control the dissemination of hypervirulent carbapenem-resistant K. pneumonia in public hospitals.