Abstract
The presence of the plasmid-mediated colistin resistance encoding mcr gene family in the Enterobacteriaceae is one of the crucial global concerns. The use of colistin in livestock rearing is believed to be the cause of mcr gene spreading and is of impact to public health. The objective of this research was to detect the frequency and virulent genes of mcr-positive Escherichia coli (MCRPE) in fecal samples from healthy pigs in a contract farming system across Thailand. A total of 696 pooled samples were derived from 80 farms, located in 49 provinces across six regions of Thailand. The colistin-resistant E. coli were identified by MALDI-TOF mass spectrometry and antimicrobial susceptibility testing by broth microdilution. The antibiogram was determined using an automated susceptibility machine, and the genetic characteristics were investigated for mcr-1–5 genes, phylogenetic group, replicon types, and virulent genes. In total, 31 of 696 samples were positive, with E. coli containing mcr-1 or combination of mcr-1 and mcr-3 with incidence of 4.45 and 0.43%. Phylogenetic groups A and B1 and the IncF and IncFIB replicon types were predominantly found in the MCRPE located in the central area, with multidrug-resistant traits against 3–14 types of antimicrobials. Additionally, 19 of 31 isolates identified as enterotoxigenic E. coli were with the stap and stb (enterotoxin-encoding genes). In conclusion, a low carriage rate of mcr-positive E. coli was detected in the large-scale farming of healthy pigs. The association between multidrug-resistant MCRPE and their pathogenic potential should be of concern.
Highlights
Antimicrobial resistance (AMR) is an emerging concern for both human and animal sectors of the world
Porcine Colistin Resistance Escherichia coli in food production and the likelihood of exposure of farmers to resistant bacteria
A total of 105 colistin-resistant E. coli from the 696 samples were isolated using the eosin methylene blue (EMB) media
Summary
Antimicrobial resistance (AMR) is an emerging concern for both human and animal sectors of the world. The inappropriate use of antimicrobials in clinical settings and, most importantly, in livestock farming imposes social and economic burdens on society [1]. The diminishing number of active (effective) antimicrobial agents to treat sick farm animals is accompanied by the downfall. Porcine Colistin Resistance Escherichia coli in food production and the likelihood of exposure of farmers to resistant bacteria. Escherichia coli, a commensal microbe, can accumulate resistance genes. It is widely used as a representative example for monitoring resistance genes, especially for horizontal gene transfer [2]. The assessment of mobile genetic elements from commensal E. coli could highlight the AMR transmission between hosts [3]
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