The global distribution and spread of the mobilized colistin resistance gene mcr-1

TLDR

Colistin is a last‑line antibiotic for carbapenem‑resistant Enterobacteriaceae, and the plasmid‑mediated mcr‑1 gene poses a significant global public‑health threat. We aim to map the global distribution of mcr‑1 by characterizing 457 sequenced isolates. We analyzed these isolates to examine plasmid types and phylogenetic relationships. All circulating mcr‑1 elements trace back to a single IS Apl1 mobilization in the mid‑2000s, then expanded rapidly to worldwide distribution, revealing a shared genetic background across plasmid types.

Abstract

Abstract Colistin represents one of the few available drugs for treating infections caused by carbapenem-resistant Enterobacteriaceae . As such, the recent plasmid-mediated spread of the colistin resistance gene mcr-1 poses a significant public health threat, requiring global monitoring and surveillance. Here, we characterize the global distribution of mcr-1 using a data set of 457 mcr-1- positive sequenced isolates. We find mcr-1 in various plasmid types but identify an immediate background common to all mcr-1 sequences. Our analyses establish that all mcr-1 elements in circulation descend from the same initial mobilization of mcr-1 by an IS A pl1 transposon in the mid 2000s (2002–2008; 95% highest posterior density), followed by a marked demographic expansion, which led to its current global distribution. Our results provide the first systematic phylogenetic analysis of the origin and spread of mcr-1 , and emphasize the importance of understanding the movement of antibiotic resistance genes across multiple levels of genomic organization.