Detection and characterization of a clinical ST3204 strain coproducing NDM-16 and MCR-1.

OBJECTIVES

A plasmid-mediated colistin resistance gene, , has been reported worldwide and has caused concern regarding a major therapeutic challenge. Alarmingly, has spread into clinical carbapenem-resistant Enterobacteriaceae isolates, resulting in extensively drug-resistant and even pan drug-resistant isolates that can cause untreatable infections. In this study, we report isolation of an extensively drug-resistant strain EC1188 that coproduces NDM-16 and MCR-1 from a urine sample taken from a patient with craniocerebral injury.

MATERIALS AND METHODS

strain EC1188 was identified and subjected to genotyping, susceptibility testing and conjugation experiments. The genetic locations of and were established with southern blot hybridization. The complete genome sequence of this strain was obtained and the genetic characteristics of the - and -harboring plasmids were analyzed. In addition, comparative genetic analyses of and with closely related plasmids were also carried out.

RESULTS

Whole-genome sequencing revealed that strain EC1188 possess various resistance genes and virulence genes. S1-pulsed-field gel electrophoresis and southern blot suggested that the and genes were located on an ~65 kb plasmid and an ~80 kb plasmid, respectively. Moreover, the two genes could successfully transfer their resistance phenotype to strain C600. Sequence analysis showed that these two plasmids possessed high sequence similarity to previously reported -harboring and -harboring plasmids in China.

CONCLUSION

To the best of our knowledge, this is the first report to isolate an strain that coproduces NDM-16 and MCR-1. In addition, we characterized the -harboring plasmid for the first time. Our study further emphasizes that the co-occurrence of the two prevalent transferrable resistance plasmids in a single isolate is highly significant because infections caused by MCR-1-producing carbapenem-resistant Enterobacteriaceae isolates are increasing each year. It is imperative to perform active surveillance to prevent further dissemination of MCR-1-producing CRE isolates.