The mcr-9 Gene of Salmonella and Escherichia coli Is Not Associated with Colistin Resistance in the United States.

ABSTRACT: Reports of transmissible colistin resistance show the importance of comprehensive colistin resistance surveillance. Recently, a new allele of the mobile colistin resistance (mcr) gene family designated mcr-9, which shows variation in genetic context and colistin susceptibility, was reported. We tested over 100 Salmonella enterica and Escherichia coli isolates with mcr-9 from the National Antimicrobial Resistance Monitoring System (NARMS) in the United States for their susceptibility to colistin and found that every isolate was susceptible, with an MIC of ≤1 μg/ml. Long-read sequencing of 12 isolates revealed mcr-9 on IncHI plasmids that were either independent or integrated into the chromosome. Overall, these results demonstrate that caution is nec

SUBMITTER: Tyson GH 

PROVIDER: S-EPMC7526823 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature