Co-production of MCR-1 and NDM-5 in Escherichia coli isolated from a colonization case of inpatient

Colistin is increasingly used as an antibiotic of last resort for treating carbapenem-resistant Enterobacteriaceae. Mobile colistin resistance gene mcr-1 has been increasingly reported in Enterobacteriaceae around the world. Of particular concern is the spread of mcr-1 into carbapenemase-producing Enterobacteriaceae, which results in highly drug-resistant strains that are potentially untreatable. Notably, such mcr-1 -carrying isolates harboring carbapenemase genes have been reported in animals and patients with infection. Here, we report an Escherichia coli strain carrying co-transferable mcr-1 -harboring IncX4 and bla NDM-5 -harboring IncX3 plasmids, which was recovered in the context of fecal colonization.