presenter
Osaka Public University Graduate School of Veterinary Medicine Professor Shinji Yamazaki, Project Associate Professor Sharda Prasad Awasthi, Mr. Ahmed Abououf (graduate student at the time of research), Professor Yukihiro Kaneko of our university's Graduate School of Medicine, Thammasat University, Thailand, Egyptian National Institute of Animal Health
overview
colistin*1is an antibacterial drug used against multidrug-resistant bacteria. Since 2018, many countries have banned the use of colistin in livestock, but the status of use in Thailand was not known. Thailand's open markets sell meat from small farms, while supermarkets sell meat from large farms. From July to September 2023, this research group will collect plasmids from chicken and pork sold at open markets and supermarkets in Thailand.*2Mediated colistin resistance (mcr) We attempted to detect the gene. As a result, from meat purchased on the open marketmcrGenes detected, antibiotics available on small farmsis not used properlyThe possibility was suggested.
The results of this research were published online in the international academic journal "Microbiology and Immunology" on July 6, 2026.
Figure Detection rate of colistin resistance (mcr) gene in chicken and pork purchased in open markets and supermarkets
point
- Regarding chicken and pork sold at open markets and supermarkets in Thailand,mcrTried to detect genes.
- Chicken purchased from an open market that sells meat from small farms.4%and pork13.3%frommcrgene detected. On the other hand, it was not detected in chicken and pork purchased at supermarkets that sell meat from large-scale farms (Figure).
- This suggests that antibiotics may not be used properly on small farms.
plasmid-mediatedmcrSince the gene was discovered,World Health Organization (Based on WHO recommendations, many countries have banned the use of colistin in livestock production. However, in response to the recent isolation of colistin-resistant bacteria from meat in Thailand, we believe it is necessary to once again call for the careful use of antibiotics.
Mr. Ahmed Abououf
Project Associate Professor Sharda Prasad AwasthiResearch background
Colistin is an antibiotic that has been used since the 1950s, but its use was temporarily restricted due to side effects. Later, in the 2010s, the increase in multidrug-resistant bacterial infections became a major problem, and colistin was once again used as a last resort. On the other hand, in 2016, plasmid-mediated colistin resistance (mcr) gene was discovered, which shocked the world because continued use of colistin could lead to the spread of resistant bacteria. Against this background, in 2017, the World Health Organization (WHO) recommended against the use of colistin in livestock for the purposes of promoting growth and preventing infectious diseases, and since 2018, the use of colistin in livestock has been banned in many countries, including Thailand. However, the actual usage status in Thailand was not known.
Research content
From July to September 2023, this research group detected plasmid-borne viruses from 39 chicken samples and 30 pork samples purchased at open markets in Thailand, and 64 chicken samples and 19 pork samples purchased from supermarkets.mcrI tried to detect the gene. As a result, it was not detected in meat from supermarkets, but among meat from open markets, 6 chicken samples (15.4%) and 4 pork samples (13.3%).mcrThe genes were detected and many of the isolated bacteria were found to be multidrug-resistant E. coli. In addition, it is highly pathogenic and substrate-extended β-lactamase producing.*3Two strains of Klebsiella were also confirmed.
Expected effects and future developments
The results of this study indicate that while large-scale farms operated by major companies are using antibiotics appropriately, small-scale farms may not be using antibiotics appropriately. In addition, the appropriate use of antibiotics containing colistin is thought to be contributing to at least a reduction in colistin-resistant bacteria. The colistin-resistant plasmid carried by the bacteria isolated this time is*4It is important to use not only colistin but also other antibiotics appropriately, as there is a high possibility of transmission due to the use of colistin.
Funding information
This research was supported by the Japan Science and Technology Agency (JST) Next Generation Researcher Challenging Research Program JPMJSP2139 and Osaka Public University Fundamental Research Grants and Educational Funds.
Glossary
*1 Colistin: An antibacterial drug that is a polypeptide consisting of multiple amino acids that damages bacterial cell membranes.
*2 Plasmid: A gene that exists separately from the bacterial chromosomal DNA and is not essential for life activities. They often carry drug resistance genes and virulence factors.
*3 Substrate-expanded beta-lactamase: An enzyme that degrades and renders not only penicillin but also various beta-lactam antibiotics ineffective based on genetic mutations.
*4 Conjugation: Transmission of genetic factors such as plasmids from one bacteria to another through contact between bacteria.
Magazine information
[Publication magazine] Microbiology and Immunology
[Paper title]Prevalence and Genomic Characterization ofmcr-Positive Enterobacteriaceae in Retail Meat in Thailand Following the Colistin Ban
【author】 Ahmed Abououf, Sharda Prasad Awasthi, Asmaa M. Elbastawesy, Noritoshi Hatanaka, Atsushi Hinenoya, Srinuan Somroop, Yukihiro Kaneko, Shinji Yamasaki
[Publication URL] https://doi.org/10.1111/1348-0421.70073
Contact information regarding research detailsOsaka Public University Graduate School of Veterinary Medicine/Osaka International Infectious Disease Research Center
Professor Shinji Yamazaki
TEL: 072-463-5653
E-mail:yshinji[at]omu.ac.jp
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Osaka Public University Public Relations Division
Person in charge: Tani
TEL: 06-6967-1834
E-mail: koho-list[at]ml.omu.ac.jp
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Source: https://www.omu.ac.jp/info/research_news/entry-25502.html