Dissemination of the mcr-1 colistin resistance gene

Abstract

Yi-Yun Liu and colleagues' Article1Liu Y-Y Wang Y Walsh TR et al.Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study.Lancet Infect Dis. 2016; 16: 161-168Summary Full Text Full Text PDF PubMed Scopus (3272) Google Scholar reporting the emergence of plasmid-mediated colistin resistance in Escherichia coli from animal, food, and human sources in China is of concern because this drug is one of the last effective drugs for the treatment of multidrug-resistant Gram-negative infections. We have screened the whole-genome sequences of about 1600 isolates from Canadian sources for the presence of mcr-1. Three isolates were identified that contained mcr-1; one human E coli isolate was identified through carbapenem-resistance sequencing projects at the National Microbiology Laboratory, and two E coli isolates were identified from the Canadian Integrated Program for Antimicrobial Resistant Surveillance (CIPARS) isolate collection. The human case involved an mcr-1-positive E coli (GN775) isolate reported from the gastrostomy tube site and rectum of a patient in Ontario, Canada in 2011, who had recently lived in Egypt for 5 years.2Ellis C Chung C Tijet N et al.OXA-48-like carbapenemase-producing Enterobacteriaceae in Ottawa, Canada.Diagn Microbiol Infect Dis. 2013; 76: 399-400Summary Full Text Full Text PDF PubMed Scopus (14) Google Scholar The isolate was multidrug resistant, was an OXA-48 producer, and had a colistin minimum inhibitory concentration of 4 mg/L. Preliminary analysis suggests that the mcr-1 was identified on a similar IncI2 plasmid backbone as has been described in China.1Liu Y-Y Wang Y Walsh TR et al.Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study.Lancet Infect Dis. 2016; 16: 161-168Summary Full Text Full Text PDF PubMed Scopus (3272) Google Scholar Two mcr-1 positive E coli isolates from the CIPARS programme were recovered from lean ground beef in January and December, 2010, purchased in Ontario, Canada. Both isolates were multidrug resistant, remaining susceptible to only the cephalosporins and amikacin, and additionally to gentamicin for one of the isolates. The mcr-1 was identified on the same contig as an IncHI2A replicon3Carattoli A Zankari E Garcia-Fernandez A et al.In silico detection and typing of plasmids using PlasmidFinder and plasmid multilocus sequence typing.Antimicrob Agents Chemother. 2014; 58: 3895-3903Crossref PubMed Scopus (2154) Google Scholar in one isolate, suggesting the mcr-1 was located on a different plasmid than the ones reported in the Chinese cases. The finding of mcr-1 in Canadian isolates further shows the widespreaddissemination of this gene in Enterobacteriaceae. To our knowledge, this is the first report of mcr-1 in the Americas. Information about the origin of the ground beef (domestic or imported) was unavailable. At least one of the foodborne isolates harboured the mcr-1 on a different Inc type suggesting the mobilisation of this gene between plasmids. Canada is developing strategies to further study the dissemination of this gene both retrospectively and prospectively, to better understand its dissemination in a One Health perspective. BT has received grants from Merck & Co, outside of the submitted work. All other authors declare no competing interests. Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological studyThe emergence of MCR-1 heralds the breach of the last group of antibiotics, polymyxins, by plasmid-mediated resistance. Although currently confined to China, MCR-1 is likely to emulate other global resistance mechanisms such as NDM-1. Our findings emphasise the urgent need for coordinated global action in the fight against pan-drug-resistant Gram-negative bacteria. Full-Text PDF