Research News

mcr-positive meat


Pork and chicken in Thailand were tested for mcr after prophylactic colistin use ban.

Credit: Osaka Metropolitan University

An Osaka Metropolitan University-led research team investigated the prevalence and characteristics of mcr-positive Enterobacteriaceae in retail meat in Thailand following the national ban on prophylactic colistin use in food producing animals. A total of 152 meat samples (103 chicken and 49 pork) were collected from supermarkets and open markets between July and September 2023. Samples were screened for mcr-1 to mcr-5 using multiplex PCR. 

None of the samples from supermarkets tested positive, whereas mcr genes were detected in 15.4% and 13.3% of chicken and pork samples, respectively, from open markets, with mcr-1 and/or mcr-3 identified. A total of 21 isolates were recovered from PCR-positive samples (11 from chicken and 10 from pork). Escherichia coli was the predominant species, followed by Klebsiella pneumoniae. All mcr-positive isolates exhibited multidrug resistance. Whole-genome sequencing was performed for 19 non-clonal isolates. One K. pneumoniae strain from a pork sample co-harbored mcr-1 and mcr-8, representing the first report of this combination in the animal sector in Thailand. In addition, virulence-associated genes, including adhesion factors, toxins, and iron acquisition systems, were identified in selected isolates. Core genome SNP-based phylogenetic analysis revealed substantial genomic diversity among the isolates, suggesting relatedness to strains reported prior to the colistin ban. 

These findings indicate that retail meat from open markets may serve as an important route for the transmission of mcr-positive bacteria in Thailand and highlight the urgent need to incorporate systematic retail meat surveillance into national antimicrobial resistance monitoring programs.

Paper information

Journal: Microbiology and Immunology
Title: Prevalence and Genomic Characterization of mcr-Positive Enterobacteriaceae in Retail Meat in Thailand Following the Colistin Ban
DOI: 10.1111/1348-0421.70073
Authors: Ahmed Abououf, Sharda Prasad Awasthi, Asmaa M. Elbastawesy, Noritoshi Hatanaka, Atsushi Hinenoya, Srinuan Somroop, Yukihiro Kaneko, Shinji Yamasaki
Published:  6 July 2026
URL: https://doi.org/10.1111/1348-0421.70073

Contact

Shinji Yamasaki

Graduate School of Veterinary Science
Email: yshinji[at]omu.ac.jp

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