Antibiotic manure turns fields into breeding grounds for resistant germs

Even biogas plants can not filter residual antibiotics

Tons of antibiotics are used year after year in livestock to keep animals healthy in mass farming. A large part of the antibiotics is excreted by the animals again and thus enters the manure. This is then applied to the fields. As a result, residues of antibiotics are transported unfiltered to agricultural land, where increasingly resistant germs prevail. This is reported by the Deutsche Bundesstiftung Umwelt from the results of a current research project.

In a recent project, the Justus-Liebig-Universität Gießen was commissioned by the German Environmental Foundation (DBU) to investigate the links between antibiotics in manure and the rise of resistant bacteria. Since manure is often fermented before being applied in biogas plants, it was examined whether antibiotics can be eliminated there to reduce the inputs into the environment. The project comes to the conclusion that unfortunately this is not possible.

Every day antibiotics residues are applied in the manure to fields worldwide. As a result, increasingly resistant germs settle in the soils of agricultural land. (Image: dietwalther / fotolia.com)

Antibiotics must be reduced in the stable

"Antibiotics have to be reduced when they are awarded in the barn in order to protect humans, animals and the environment," emphasizes DBU Secretary General Alexander Bonde in a press release on the project. In the joint project, the researchers looked for alternative solutions to filter out the antibiotics from the manure. The active ingredients, however, withstood different temperatures and additions of acids and salts. The filter trials had no significant influence on the remaining stocks.

A global problem

According to information from the Federal Office for Consumer Protection and Food Safety, 733 tonnes of antibiotics were used in livestock farming in Germany alone in 2017. This is not the case only in Germany. "Worldwide antibiotics are found in manure samples and fermentation residues from biogas plants," explains project manager Dr. Ing. Astrid Spielmeyer from the Institute of Food Chemistry and Food Biotechnology at the University of Gießen. In regions with intensive agriculture, both antibiotics levies via veterinarians and resistant bacterial contamination in soil are the most pronounced.

Agricultural land as a nest for resistant pathogens

"About one-third of antibiotics used in veterinary medicine are antibacterial sulfonamides and tetracyclines," says Spielmeyer. Tetracycline is also used in humans as a broad spectrum antibiotic. This active ingredient is used in particular when the pathogens can not be determined accurately. For the two antibiotic groups mentioned already resistant pathogens have been detected in the fields. The results of the project were published in a freely available final report on the DBU website. (Vb)

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