Farm animals and aquaculture: significant reservoirs of mobile colistin resistance genes

Abstract

Summary Colistin resistance has attracted substantial attention after colistin was considered as a last‐resort drug for the treatment of infections caused by carbapenem‐resistant and/or multidrug‐resistant (MDR) Gram‐negative bacteria in clinical settings. However, with the discovery of highly mobile colistin resistance (mcr) genes, colistin resistance has become an increasingly urgent issue worldwide. Despite many reviews, which summarized the prevalence, mechanisms, and structures of these genes in bacteria of human and animal origin, studies on the prevalence of mobile colistin resistance genes in aquaculture and their transmission between animals and humans remain scarce. Herein, we review recent reports on the prevalence of colistin resistance genes in animals, especially wildlife and aquaculture, and their possibility of transmission to humans via the food chain. This review also gives some insights into the routine surveillance, changing policy and replacement of polymyxins by polymyxin derivatives, molecular inhibitors, and traditional Chinese medicine to tackle colistin resistance.

Emergence of Carbapenem- and Tigecycline-Resistant Proteus cibarius of Animal Origin

“…To better investigate the molecular epidemiology, genomic evolution, and functional analysis and avoid confusion in tet (X) designations, a clear nomenclature scheme acceptable to researchers worldwide should be proposed as soon as possible. Because mcr genes exist in certain bacterial species as housekeeping genes and certain alleles leap over species boundary limits to Enterobacterales via mobile elements like Tn 6330 ( Li et al, 2016 ; Shen et al, 2020 ), tet (X) genes may behave similarly because they exist as core genes in certain bacteria and transfer to Enterobacterales by mobile elements like IS CR2 . Thus, the mcr nomenclature scheme may be a good example when it comes to tet (X) designation ( Partridge et al, 2018 ).…”

Prevalence and Epidemiology of Multidrug-Resistant Pathogens in the Food Chain and the Urban Environment in Northwestern Germany

“…After the first identification of the mcr-1 gene in 2015, numerous reports about its occurrence in humans in veterinary medicine demonstrated that the gene was globally disseminated, mainly in E. coli [ 11 ]. In this study, we found mcr genes in 18% of all 505 samples with the highest prevalence in samples from a poultry slaughterhouse (43%).…”

“…While Col-E are occasionally detected when screening for commensal E. coli, no selective screening for Col-E is applied within the EU-wide monitoring program. Recently, it was reported that Col-E harboring the plasmid-located colistin resistance-mediating mcr genes had emerged in livestock [ 10 , 11 ]. Here, we aimed to assess the prevalence of Col-E along the meat production chain, to characterize the mcr genes, and to determine whether very recent reductions of colistin use in Germany already led to a decrease in Col-E. As culture-based detection alone was reported to be difficult due to overgrowth by intrinsically resistant species [ 12 ], it seems feasible to use a combined approach to selectively screen for Col-E and mcr genes.…”

Correlation between Exogenous Compounds and the Horizontal Transfer of Plasmid-Borne Antibiotic Resistance Genes

“…Additionally, the mobilized colistin resistance gene mcr-1- positive Enterobacteriaceae [ 8 ] from different origins has been identified in over 50 countries across six continents. Meanwhile, various mcr-1 variants, such as mcr - 2/3/4/5/6/7/8/9/10 , were also identified in bacteria from various sources [ 9 ]. Previous research has shown that sub-minimum inhibition concentrations (MIC) of specific antibiotics can profoundly facilitate the conjugation process, thus improving the relatively low conjugation efficiency in the experimental conditions [ 10 ].…”