Dissemination of gene via an IncX3-type plasmid among non-clonal in China.

Background: The emergence and spread of New Delhi metallo-β-lactamase-producing has been a serious challenge to manage in the clinic due to its rapid dissemination of multi-drug resistance worldwide. As one main type of carbapenemases, New Delhi metallo-β-lactamase (NDM)is able to confer resistance to almost all β-lactams, including carbapenems, in . Recently, New Delhi metallo-β-lactamase-5 attracted extensive attention because of increased resistance to carbapenems and widespread dissemination. However, the dissemination mechanism of gene remains unclear.

Methods: A total of 224 carbapenem-resistant isolates (CRE) were collected from different hospitals in Zhejiang province. NDM-5-positive isolates were identified and subjected to genotyping, susceptibility testing, and clinical data analysis. We established the genetic location of with southern blot hybridisation, and analysed plasmids containing with filter mating and DNA sequencing.

Results: Eleven New Delhi metallo-β-lactamase-5 (NDM-5)-producing strains were identified, including 9 strains, 1 strain, and strain. No epidemiological links for isolates were identified by multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). S1-PFGE and southern blot suggested that the gene was located on a 46-kb IncX3-type plasmid in all isolates. Nine of the 11 isolates (81.8%) tested could successfully transfer their carbapenem-resistant phenotype to strain C600. Moreover, sequence analysis further showed that this plasmid possessed high sequence similarity to most of previously reported -habouring plasmids in China.

Conclusion: The present data in this study showed the IncX3 type plasmid played an important role in the dissemination of in . In addition, to the best of our knowledge, this report is the first to isolate both and strains carrying from one single patient, which further indicated the possibility of transmission among diverse species. Close surveillance is urgently needed to monitor the further dissemination of NDM-5-producing isolates.