AUTHOR=Karim Md Rezaul , Zakaria Zunita , Hassan Latiffah , Faiz Nik Mohd , Ahmad Nur Indah 

TITLE=The occurrence and molecular detection of mcr-1 and mcr-5 genes in Enterobacteriaceae isolated from poultry and poultry meats in Malaysia

JOURNAL=Frontiers in Microbiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2023.1208314

DOI=10.3389/fmicb.2023.1208314

ISSN=1664-302X

ABSTRACT=<p>The advent of antimicrobials-resistant (AMR), including colistin-resistant bacteria, poses a significant challenge to animal and human health, food safety, socio-economic growth, and the global environment. This study aimed to ascertain the colistin resistance prevalence and molecular mechanisms of colistin resistance in <italic>Enterobacteriaceae</italic>. The colistin resistance was determined using broth microdilution assay, PCR; and Sanger sequencing of <italic>mcr</italic> genes responsible for colistin resistance in <italic>Enterobacteriaceae</italic> (<italic>n</italic> = 627), including <italic>Escherichia coli</italic> (436)<italic>, Salmonella</italic> spp. (<italic>n</italic> = 140), and <italic>Klebsiella pneumoniae</italic> (<italic>n</italic> = 51), obtained from chicken and chicken meats. Out of 627 <italic>Enterobacteriaceae</italic>, 8.6% of isolates exhibited colistin resistance phenotypically. Among these colistin resistant isolates, 9.3% (<italic>n</italic> = 37) were isolated from chicken meat, 7.2% (<italic>n</italic> = 11) from the cloacal swab of chicken and 7.9% (<italic>n</italic> = 6) from the litter samples. Overall, 12.96% of colistin-resistant isolates were positive with <italic>mcr</italic> genes, in which <italic>mcr-1</italic> and <italic>mcr-5</italic> genes were determined in 11.11% and 1.85% of colistin-resistant isolates, respectively. The <italic>E. coli</italic> isolates obtained from chicken meats, cloacal swabs and litter samples were found positive for <italic>mcr-1</italic>, and <italic>Salmonella</italic> spp. originated from the chicken meat sample was observed with <italic>mcr-5</italic>, whereas no <italic>mcr</italic> genes were observed in <italic>K. pneumoniae</italic> strains isolated from any of the collected samples. The other colistin resistance genes, including <italic>mcr-2, mcr-3, mcr-4, mcr-6, mcr-7, mcr-8, mcr-9,</italic> and <italic>mcr-10</italic> were not detected in the studied samples. The <italic>mcr-1</italic> and <italic>mcr-5</italic> genes were sequenced and found to be 100% identical to the <italic>mcr-1</italic> and <italic>mcr-5</italic> gene sequences available in the NCBI database. This is the first report of colistin resistance <italic>mcr-5</italic> gene in Malaysia which could portend the emergence of <italic>mcr-5</italic> harboring bacterial strains for infection. Further studies are needed to characterize the <italic>mr-5</italic> harbouring bacteria for the determination of plasmid associated with <italic>mcr-5</italic> gene.</p>