Chromosomally Encoded <i>mcr-5</i> in Colistin-Nonsusceptible Pseudomonas aeruginosa

Abstract

Whole-genome sequencing (WGS) of historical <i>Pseudomonas aeruginosa</i> clinical isolates identified a chromosomal copy of <i>mcr-5</i> within a Tn<i>3</i>-like transposon in <i>P. aeruginosa</i> MRSN 12280. The isolate was nonsusceptible to colistin by broth microdilution, and genome analysis revealed no mutations known to confer colistin resistance. To the best of our knowledge, this is the first report of <i>mcr</i> in colistin-nonsusceptible <i>P. aeruginosa</i>.