blaNDM and mcr-1 to mcr-5 Gene Distribution Characteristics in Gut Specimens from Different Regions of China

Abstract

Antibiotic resistance has become a global public health concern. To determine the distribution characteristics of <i>mcr</i> and <i>bla</i>_NDM 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 <i>mcr</i> and 0.41% (29/6991) for <i>bla</i>_NDM, as detected in gut specimens from seven regions, throughout 2010 to 2019, but not detected in 2020. The detection rate of <i>mcr</i> showed significant differences among various sources: livestock and poultry (14.81%) > diarrhea patients (1.43%) > wild animals (0.36%). The detection rate of <i>bla</i>_NDM 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 <i>mcr</i> genotypes in livestock and poultry. All instances of coexistence of the <i>mcr-1</i> and <i>bla</i>_NDM genes, as well as coexistence of <i>mcr</i> genotypes within single specimens, and most new <i>mcr</i> subtypes came from livestock, and poultry environments. Our study indicates that the emergence of <i>mcr</i> and <i>bla</i>_NDM 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.