Widespread distribution of mcr-1-bearing bacteria in the ecosystem, 2015 to 2016

Abstract

The recently discovered colistin resistance-encoding element, mcr-1, adds to the list of mobile resistance genes whose products rapidly erode the antimicrobial efficacy of not only the commonly used antibiotics, but also the last line agents of carbapenems and colistin. The relative prevalence of mcr-1-bearing strains in various ecological niches including 1,371 food samples, 480 animal faecal samples, 150 human faecal samples and 34 water samples was surveyed using a novel in-house method. Bacteria bearing mcr-1 were commonly detected in water (71% of samples), animal faeces (51%), food products (36%), and exhibited stable carriage in 28% of human subjects surveyed. Such strains, which exhibited variable antibiotic susceptibility profiles, belonged to various Enterobacteriaceae species, with Escherichia coli being the most dominant in each specimen type. The mcr-1 gene was detectable in the chromosome as well as plasmids of various sizes. Among these, two conjugative plasmids of sizes ca 33 and ca 60 kb were found to be the key vectors that mediated mcr-1 transmission in organisms residing in various ecological niches. The high mcr-1 carriage rate in humans found in this study highlights the importance of continued vigilance, careful antibiotic stewardship, and the development of new antimicrobials.

Fecal Carriage and Molecular Epidemiology of mcr-1-Harboring Escherichia Coli from Children in Southern China.

“…These results indicate that the resistance level of colistin in E. coli from children was different from that of adults. The 21 mcr-1 positive strains had higher resistance rates to tobramycin and doxycycline, 33.3% and 42.8%, respectively, than the other antibiotics, particularly carbapenem antibiotics; all isolates were sensitive to imipenem and meropenem, which is similar to observation in several other studies [11,18,19].…”

“…The mcr-1 gene is widely spread in Enterobacteriaceae, especially in K. pneumoniae and E. coli isolated from food sources, environment, and humans [3,25] In the present study, 18 strains successfully transmitted the mcr-1 gene to E. coli J53. Previous studies have shown that mcr-1 is present on many types of plasmids, such as IncI2, IncHI2, IncX4, etc.…”

Massive analysis of 64’628 bacterial genomes to decipher a water reservoir and origin of mobile colistin resistance (mcr) gene variants: is there another role for this family of enzymes?

“…E. coli and E. cloacae ) collected from urban surface water, rivers or lakes 37–39 . This gene was reported from wastewater treatment plants in China 40 , in South Africa 41 , in Italia 42 , in Germany 43 or from hospital sewage water in China 44 . This variant was also reported from various bacteria isolated from other water environments, such as seawater in Algeria 45 , from top water in rural China 46 or from freshwater of intensive aquaculture in China 17 .…”

MCR-1 Colistin Resistance in Escherichia coli Wildlife: A Continental Mini-review

“…The persistence of MCR-1 in the human GI tract microflora can cause further contamination of the water systems through disposal of waste water containing human faeces. Fresh water systems outside these transmission routes remain clear of MCR-1 contamination [12].…”