Abstract
Antibiotic resistance has become a global public health concern. To determine the distribution characteristics of mcr and blaNDM in China, gene screening was conducted directly from gut specimens sourced from livestock and poultry, poultry environments, human diarrhea patients, and wild animals from 10 regions, between 2010–2020. The positive rate was 5.09% (356/6991) for mcr and 0.41% (29/6991) for blaNDM, as detected in gut specimens from seven regions, throughout 2010 to 2019, but not detected in 2020. The detection rate of mcr showed significant differences among various sources: livestock and poultry (14.81%) > diarrhea patients (1.43%) > wild animals (0.36%). The detection rate of blaNDM was also higher in livestock and poultry (0.88%) than in diarrhea patients (0.17%), and this was undetected in wildlife. This is consistent with the relatively high detection rate of multiple mcr genotypes in livestock and poultry. All instances of coexistence of the mcr-1 and blaNDM genes, as well as coexistence of mcr genotypes within single specimens, and most new mcr subtypes came from livestock, and poultry environments. Our study indicates that the emergence of mcr and blaNDM genes in China is closely related to the selective pressure of carbapenem and polymyxin. The gene-based strategy is proposed to identify more resistance genes of concern, possibly providing guidance for the prevention and control of antimicrobial resistance dissemination.
Highlights
IntroductionCarbapenem usage has not been approved for use in the breeding industry in China, new blaNDM subtypes and an epidemic of resistant bacterial strains have appeared in livestock and poultry [11,12]
To further determine the distribution of mcr and blaNDM from different sources—carried by the bacteria selected by antibiotic selective pressures and normal flora with resistance—this study was conducted based on gut specimen detection strategy and a One Health approach
The gene pools of mcr or blaNDM reflect resistance genes carried by normal flora when antibiotic pressure is low, and genes carried by the bacteria selected by antibiotic pressure
Summary
Carbapenem usage has not been approved for use in the breeding industry in China, new blaNDM subtypes and an epidemic of resistant bacterial strains have appeared in livestock and poultry [11,12]. The mcr-1 gene was first discovered in pigs in 2016 [13] and 10 genotypes and multiple subtypes have since been found [14,15,16,17,18]. The mcr-positive or polymyxin-resistant strains are found in livestock, humans, and environments [21,22,23], and in wild animals such as macaques and migratory birds [24,25,26]
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