Study Do residues of agriculture lead to increased antibiotic resistance?

Physicians are studying the use of antibiotics in agriculture

Every year, farmers buy huge quantities of antibiotics approved for use in cows, pigs, poultry and other livestock. Not infrequently, the feces of these animals is then used as fertilizer. As a result, traces of the drugs are released into the environment. Researchers fear that agriculture could contribute significantly to the rise of antibiotic-resistant bacteria.

The researchers from the Buffalo College of Arts and Sciences found that many traces of antibiotics were released into the environment through agriculture, which could lead to an increase in antibiotic-resistant bacterial strains.

Does the feces of animals in agriculture lead to an increase in resistance to antibiotics? (Image: dietwalther / fotolia.com)

Two waste treatment systems have been closely studied

Two of the most advanced waste treatment systems used in agriculture to degrade antibiotics can not completely retain or remove drug residues, according to researchers. Both technologies leave traces of antibiotics, which include both the active ingredients themselves, as well as the molecules into which the active ingredients decompose, explain the experts. Solid excrements were also examined in more detail, which are often filtered out before further processing.

Dung solids contain a lot of antibiotics

The researchers found that this solid can contain high levels of antibiotics. This discovery is particularly troubling because it is often released into the environment when used as litter or fertilizer. It was hoped that advanced processing technologies could remove antibiotics. However, as it turned out, these methods were not as effective as they were supposed to be. Diana Aga from the University of Buffalo College of Arts and Sciences.

Composting could solve the problem

There is, however, hope: A multi-stage process, which also includes the composting at the end of the system, could significantly reduce the amount of antibiotics, the experts report. Earlier studies of poultry manure have shown that this process works very well. After about 150 days, a reduction of antibiotics by 70 percent can be achieved, the scientists say.

Treatment systems were not designed to remove antibiotics

According to the US Food and Drug Administration, more than 30 million pounds of antibiotics approved for use in food producing livestock were sold or distributed in the United States in 2016. This is only a fraction of the world's antibiotics used annually in humans and animals, explain the experts. Although research has focused on dairy farms, the results point to a bigger problem. None of the studied treatment systems was designed to remove antibiotics from the waste, Aga emphasizes. The aim is rather to reduce odors and produce biogas or recycle water.

Problem is not just agriculture

The problem is not limited to agriculture: waste treatment systems, including those designed for the treatment of urban waste, hospital waste and even waste from the antibiotic industry, do not have antibiotics as its main objective. As the increase in antimicrobial resistance in the environment progresses, antibiotics in the environment are an important global problem. Solutions must be found urgently, the experts emphasize.

People use antibiotics in many cases. This has led to an increase in resistance to antibiotics in recent decades. (Image: denisismagilov / fotolia.com)

Two dairy farms were closely examined

To conduct the research, scientists visited two dairy farms in Upstate New York. Both plants remove much of the cow dung solids before subjecting the remaining sludge to high-tech waste management techniques. Thereafter, one of the companies used microorganisms and pasteurization to convert organic material to manure and produce biogas. The other company used so-called reverse osmosis. Both technologies reduced the residues of antibiotics in the manure, but could barely reduce the remaining antibiotics in the solids.

Most of the solids remain untreated

The current research findings are particularly worrying, as research has also shown that antibiotic compounds tend to migrate from the liquid parts of the manure into the solids during treatment, say the physicians. The processing techniques are only performed after most of the solids have already been separated from the raw mash, meaning that most of the solids remain untreated. The study found that both the liquid and the solid part of the sludge may contain genes that confer resistance to antibiotics. Although reverse osmosis can effectively remove such ionophores from the liquid part of the manure, many of the ionophores have already migrated to the solid part of the raw mist prior to treatment, which is removed before reverse osmosis begins, the researchers explain.

Further research is needed

Different waste management techniques must now be explored more closely to reduce the spread of antibiotics and resistant bacteria. Composting is an area that should be specially considered. Results from an ongoing study on this topic are promising, Aga explains. The physicians published the results of their study on the two different investigated waste treatment systems in the English language magazines "Chemosphere" and "Environmental Pollution". (As)