Colistin Resistant mcr Genes Prevalence in Livestock Animals (Swine, Bovine, Poultry) from a Multinational Perspective. A Systematic Review

Abstract

The objective of this review is to collect and present the results of relevant studies on an international level, on the subject of colistin resistance due to mcr genes prevalence in livestock animals. After a literature search, and using PRISMA guidelines principles, a total of 40 swine, 16 bovine and 31 poultry studies were collected concerning mcr-1 gene; five swine, three bovine and three poultry studies referred to mcr-2 gene; eight swine, one bovine, two poultry studies were about mcr-3 gene; six swine, one bovine and one poultry manuscript studied mcr-4 gene; five swine manuscripts studied mcr-5 gene; one swine manuscript was about mcr-6, mcr-7, mcr-8, mcr-9 genes and one poultry study about mcr-10 gene was found. Information about colistin resistance in bacteria derived from animals and animal product foods is still considered limited and that should be continually enhanced; most of the information about clinical isolates are relative to enteropathogens Escherichia coli and Salmonella spp. This review demonstrates the widespread dispersion of mcr genes to livestock animals, indicating the need to further increase measures to control this important threat for public health issue.

Longitudinal Monitoring Reveals Persistence of Colistin-Resistant Escherichia coli on a Pig Farm Following Cessation of Colistin Use

“…The mcr genes have been reported not only from various livestock origins (pigs, poultry, bovine) ( 10 , 11 ) and food products ( 12 ) but also from the environment as well as from humans ( 13 ). Since the extensive usage of colistin in livestock farms played a major role in the occurrence of colistin resistant mcr genes, controlling the dissemination of these resistant genes from farms to the environment has become a critical concern ( 14 ). Moreover, mcr genes could be co-located with other important antibiotic resistance genes such as Extended spectrum beta-lactamase (ESBL) and carbapenemase genes ( 15 , 16 ).…”

Genomic Changes within a Subset of IncI2 Plasmids Associated with Dissemination of mcr-1 Genes and Other Important Antimicrobial Resistance Determinants

“…The first discovery of mcr-1 [ 4 ] set off an intensive search for the gene in many parts of the world. It was found fairly frequently in Southeast Asia and less often in the rest of the world but widely scattered in all the continents save Antartica [ 20 ]. Most of the isolations came from farm animals, notably pigs.…”

“…Most of the isolations came from farm animals, notably pigs. At the time of the first isolation the use of colistin was not regulated in much of Southeast Asia and was commonly used for promoting growth [ 20 ] and for prophylaxis for gastrointestinal disease during weaning [ 21 ]. It is apparent that the use of colistin created selective pressure favoring bacteria carrying mcr-1 .…”

Epidemiology and Traits of Mobile Colistin Resistance (mcr) Gene-Bearing Organisms from Horses

“…Therefore, there is a need to understand the magnitude, genetic context, and epidemiological relationships of mcr -gene-bearing organisms that have been isolated from different ecological niches. Reports on mcr -gene-mediated COL resistance in animals, especially in food-producing animals (FPAs), are more abundant than those in humans and the environment [ 13 , 16 , 20 , 23 , 26 , 27 , 28 , 29 , 30 , 31 ], indicating that animals are a huge reservoir for plasmid-mediated COL resistance (PMCR) and warrants increased surveillance of animal sources as part of a process to reduce the spread of COL resistance. However, horses appear to be an underestimated reservoir of mcr -gene-bearing organisms.…”