Epidemiology of mobile colistin resistance genes mcr-1 to mcr-9

Abstract

The identification of the first mobile colistin resistance (MCR) gene, mcr-1, in 2015 triggered a rash of mcr screening reports. Subsequently, nine MCR-family genes and their variants have been described. However, a comprehensive overview concerning the epidemiology of the whole MCR family, which is essential for facilitating rational interventions against mcr dissemination, is lacking. Here, based on the National Database of Antibiotic Resistant Organisms and published studies, we have summarized the latest epidemiological characteristics of the mcr genes.

A novel host of MCR‐5 belonging to Enterobacter spp. isolated from hospital sewage water

“…So far, 10 mcr variants have been identified, and some of them have widely disseminated among different species recovered from humans, animals and environment (Poirel et al ., 2017, Wang et al ., 2020). Epidemiological studies show that mcr‐5 is one of the most prevalent members among mcr family (Ling et al ., 2020) and has widely distributed in a variety of Gram‐negative bacterial species. Enterobacteriaceae is known as one of major reservoirs of mcr s, while mcr‐5 has only been detected in Escherichia coli and Salmonella enterica prior to this study (Borowiak et al ., 2017, Hammerl et al ., 2018).…”

Mobile Colistin Resistance Gene mcr-1 Detected on an IncI2 Plasmid in Salmonella Typhimurium Sequence Type 19 from a Healthy Pig in South Korea

“…The mcr genes encode phosphoethanolamine transferases that modify the lipopolysaccharides of the outer membrane in Gram-negative bacteria, which leads to reduced susceptibility or resistance to colistin [5]. Since the first report of the mcr-1 gene in Escherichia coli in China in 2016 [6], the MCR-family genes have been detected in several other Enterobacteriaceae in many countries [7]. The mcr-1 and mcr-9 are the most widely disseminated MCR-family genes, being identified in 40 countries across six continents; mcr-3 and mcr-5 are the next most widely spread genes.…”

“…The mcr-1 and mcr-9 are the most widely disseminated MCR-family genes, being identified in 40 countries across six continents; mcr-3 and mcr-5 are the next most widely spread genes. The remaining MCR-family genes are disseminated across small areas [7]. In Korea, mcr-1, mcr-3, and mcr-9 genes were identified in Enterobacteriaceae isolated mainly from food animals [8][9][10].…”

Genome Characterization of mcr-1–Positive Escherichia coli Isolated From Pigs With Postweaning Diarrhea in China

“…So far, nine allelic variants of mcr-1 ( mcr-2 to mcr-10 ) have been detected ( 20 , 21 ). In addition, they have large number of variants, such as mcr-1 ( mcr-1.1 to mcr-1.22 ), mcr-2 ( mcr-2.1 to mcr-2.3 ), mcr-3 ( mcr-3.1 to mcr-3.30 ), mcr-4 ( mcr-4.1 to mcr-4.6 ), mcr-5 ( mcr-5.1 to mcr-5.4 ), and mcr-8 ( mcr-8.1 and mcr-8.2 ) ( 22 ). Our previous study found that the resistance rate to colistin was 20.47% in 171 E. coli isolates ( 6 ), and a recent article reported that direct sample testing rates of mcr-1 were higher than the rates of mcr-1 –positive E. coli (64.6 vs. 49.2%) ( 23 ).…”