AUTHOR=Khine Nwai Oo , Lugsomya Kittitat , Kaewgun Benjarong , Honhanrob Lertrob , Pairojrit Panupong , Jermprasert Suthipat , Prapasarakul Nuvee 

TITLE=Multidrug Resistance and Virulence Factors of Escherichia coli Harboring Plasmid-Mediated Colistin Resistance: mcr-1 and mcr-3 Genes in Contracted Pig Farms in Thailand

JOURNAL=Frontiers in Veterinary Science

VOLUME=7

YEAR=2020

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2020.582899

DOI=10.3389/fvets.2020.582899

ISSN=2297-1769

ABSTRACT=<p>The presence of the plasmid-mediated colistin resistance encoding <italic>mcr</italic> gene family in the <italic>Enterobacteriaceae</italic> is one of the crucial global concerns. The use of colistin in livestock rearing is believed to be the cause of <italic>mcr</italic> gene spreading and is of impact to public health. The objective of this research was to detect the frequency and virulent genes of <italic>mcr-</italic>positive <italic>Escherichia coli</italic> (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 <italic>E. coli</italic> 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 <italic>mcr-1–5</italic> genes, phylogenetic group, replicon types, and virulent genes. In total, 31 of 696 samples were positive, with <italic>E. coli</italic> containing <italic>mcr-1</italic> or combination of <italic>mcr-1</italic> and <italic>mcr-3</italic> 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 <italic>E. coli</italic> were with the <italic>stap</italic> and <italic>stb</italic> (enterotoxin-encoding genes). In conclusion, a low carriage rate of <italic>mcr-</italic>positive <italic>E. coli</italic> was detected in the large-scale farming of healthy pigs. The association between multidrug-resistant MCRPE and their pathogenic potential should be of concern.</p>