Identification and antimicrobial resistance of a mcr-1-positive multidrug-resistant Shigella sonnei isolate

ObjectiveTo identify a mcr-1-positive multidrug-resistant Shigella sonnei isolate and analyze its antibiotic resistance.

MethodsThe isolate was identified with biochemical and serological kits. Antibiotic susceptibility test was performed by using broth microdilution method, and the resistance genes were detected with PCR. Genetic polymorphism and plasmid profiles were analyzed by using PFGE, and Southern hybridization were performed. The horizontal transfer ability of mcr-1 gene was verified by plasmid conjugation transfer test.

ResultsA mcr-1-positive multidrug resistant S. sonnei was isolated in Guangxi, which was resistant to cephalosporin, azithromycin and polymyxin. The mcr-1, mph(A) and bla_CTX-M-14 genes were detected in two distinct plasmids, and the mcr-1 gene could be transfered horizontally through plasmid conjugation transfer.

ConclusionIt is necessary to strengthen the surveillance for co-resistance to ceftriaxone and azithromycin of Shigella, especially Shigella sonnei, and the molecular epidemiological study of mcr-1 transmission to provide evidence for the rational use of antibiotics in the treatment of shigellosis.