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New research shows high levels of resistant Salmonella present in pork

New analysis of pork products in Vietnam shows worrying results when it comes to antibiotic resistant bacteria.
A graphic depicting a map of Vietnam and a bowl of Vietnamese Pho

The research, published in the journal Frontiers in Veterinary Sciences, was lead by scientists at the London School of Hygiene & Tropical Medicine’s Department of Infection Biology. The analysis looked at antibiotic resistance present in Salmonella strains isolated from pork meat available at food retail outlets. The research looked at multi-drug resistance – when a strain shows resistance to many different antimicrobials. Scientists also specifically looked for the presence of the mcr-1 gene, which can give high-level resistance to the last-resort antibiotic colistin.

As well as slaughterhouses, the work examined pork samples from retail outlets classed as wet markets, supermarkets or ‘boutique’ – where the retailers claim the pork is high quality, traceable and environmentally friendly. These outlets typically market their products towards higher income consumers. The study showed that pork in these outlets still contained non-typhoidal Salmonella with high levels of multi-drug resistance, with a large proportion showing colistin resistance.

Salmonella are a family of bacteria in the family Enterobacteriaceae. The infection usually manifests with gastroenteritis including vomiting and diarrhoea, and is short lived. However in some cases, the infection can cross into the bloodstream and cause a much more severe disease, with a high number of deaths. In these cases, antibiotics are required and important to effectively treat the infection.

Commenting on the importance of the work, Niamh Holohan, from the Department of Infection Biology at the London School of Hygiene & Tropical Medicine said:

“This important research helps quantify the problem of antimicrobial resistance in pork products in Vietnam. Pork accounts for 70% of the total meat consumed in Vietnam, meaning contaminated pork poses a risk to a large number of consumers there. The prevalence of colistin resistance is particularly concerning, as this is really the last line of defense to treat invasive infections in a clinical setting.

“It's important that we have this data and quantify the problem accurately, so that we can design the best strategies to try and combat the development of further drug resistance.”

Dr Richard Stabler said “The Vietnamese government is working to reduce the use of antimicrobials used in pork production and to give consumers better information on how their food is produced. This is certainly a step in the right direction. This work showed that these retrospective samples, even from high end outlets, had concerning levels of drug resistance and further work is needed to see if the situation has improved.”

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