24 July 2018

Pig and chicken manure tested for antibiotic resistance

Resistant gut bacteria related to use of antibiotics

Testing the manure of over 9,000 pigs and chickens: researchers from Utrecht University and Wageningen University & Research didn't turn their noses up at the task. Yesterday, together with an international team, they published the results of the study into antibiotic resistance in the prestigious journal Nature Microbiology. The degree of antibiotic resistance present in the intestinal tracts of pigs and chickens raised for meat was revealed to be linked to the use of antibiotics.

The international team visited 180 pig farms and 178 poultry farms in nine European countries. There, the researchers collected manure samples from over 9,000 animals.

Greater resistance among pigs

The data showed that the quantity and type of resistance gene present in the gut of each animal varied from one species and country to the next. In other words, the animals – pigs and chickens – and the nine countries differed from one another in terms of antibiotic resistance. This reflects the differing degree to which antibiotics are used for each species and within each country. The pigs’ gut bacteria showed stronger resistance than those of the chickens, while the chickens’ intestines were home to a greater variety of resistance genes. The results of the study are relevant not only for animals, but for people as well. After all, we humans are exposed to these resistance genes via the food we eat.

New approach

The researchers opted for a new approach to measuring resistance. They collected information using DNA found in the animals’ manure. This information included codes for any antimicrobial resistance within the total gut microbiota. This is known as the resistome, and includes all resistance genes present in the gut.

Joining forces

This publication is just one of the results of international collaboration within the European EFFORT project: ‘Ecology from Farm to Fork Of microbial drug Resistance and Transmission’. The project is aimed at studying the complex epidemiology and ecology of antimicrobial resistance and the ways in which bacteria interact in animals, the food chain and the environment. Utrecht University's own Jaap Wagenaar and Haitske Graveland are coordinating the project, which began in 2013 and will run through 2018. The international team consists of nineteen partners from ten European countries (the Netherlands, Belgium, Germany, Denmark, Poland, Bulgaria, Switzerland, Italy, Spain and France). Dutch institutes that have contributed significantly to the newly published article include Utrecht University's Faculty of Veterinary Medicine (Dick Heederik, Lidwien Smit, Heike Schmitt, Roosmarijn Luiken, Liese van Gompel, Alejandro Dorado and Jaap Wagenaar) and Wageningen Bioveterinary Research in Lelystad (Alex Bossers and Dik Mevius). The EFFORT project will culminate in a symposium to be held in Tivoli Vredenburg in Utrecht this November.