RESUMEN
Polymyxin antibiotics,particularly polymyxin B and polymyxin E(colistin),are often considered a last line of defense against penicillin carbapenem-resistant Enterobacteriaceae(CRE),because of their favorable clinical antibacterial effects.However,the emergence and spread of plasmid-mediated colistin resistance genes(mcr),and their multiple isoforms,have posed a substantial threat to public health in recent years.The mcr-1 genes exhibit complexity in both host and transmis-sion routes,and diversity in both the genetic environment and ecological locus distribution.Herein,we discuss the prevalence,transmission routes,drug resistance and transmission mechanisms of mcr-1 positive isolates,on the basis of epidemiological studies of Enterobacteriaceae carrying mcr-1 worldwide.to provide a theoretical reference for researchers.