A study from the University of Gothenburg reveals that wastewater environments are more conducive to antibiotic resistance evolution than previously thought, with unique characteristics enabling resistance genes to transfer from harmless to disease-causing bacteria. The research emphasizes the need for attention on waste streams alongside efforts to reduce antibiotic use in humans and animals, in order to prevent the emergence of new antibiotic-resistant bacteria.
According to a recent study from the University of Gothenburg in Sweden, the potency of antibiotic resistance evolution in wastewater has been greatly underestimated. The research reveals that wastewater has unique properties that allow resistance genes to start their journey from harmless bacteria to those that cause disease.
Long before humans utilized antibiotics as medicines, microorganisms had already developed the production of these molecules. As a result, the ability of many bacteria in the environment to resist antibiotics is an ancient trait.
Fanny Berglund, Sahgrenska Academy at the University of Gothenburg. Credit: University of Gothenburg
Since the introduction of antibiotics in clinics, disease-causing bacteria have also started to accumulate more and more resistance genes in their DNA. This still ongoing process requires that genes, that were previously well anchored in the chromosome of certain bacterial species, first gain the ability to move around and eventually jump between species.
In a study published in the journal Communications Biology, researchers at the Centre for Antibiotic Resistance Research (CARe) in Gothenburg, Sweden present evidence for where the genes could gain their ability to move.
Important to prevent the emergence
It is known that wastewaters contain residues of antibiotics that could favor the development of antibiotic-resistant bacteria. New evidence shows that wastewaters also have characteristics allowing the resistance genes to start their journey from harmless bacteria to disease-causing bacteria.
The researchers acknowledged that it is not sufficient with antibiotics to drive the process. The species carrying the resistance genes in their chromosome also needs to be present, as well as specific sequences of DNA that could provide the ability to move the resistance genes.
By studying DNA from thousands of samples from different environments, the researchers could identify where all the key components came together. To the authors’ surprise, it was not in the gut of humans or animals, it was in wastewater sampled across the world.
“In order to fight antibiotic resistance we cannot focus only on preventing the spread of those types of resistant bacteria that are already in circulation, we also need to prevent or delay the emergence of new ones,” says Fanny Berglund, a researcher at the Sahlgrenska academy at University of Gothenburg, and the lead author of the study.
More focus on wastewater
The same research team has published several other studies showing that the environment harbors a huge variety of different resistance genes, many more than the resistance genes that we see today in bacteria causing disease.
This makes the environment a vast source for new resistance genes that one after the other acquire the ability to jump between species, to eventually end up in pathogens. The authors conclude that favoring this development by polluting the environment with antibiotics is not a good idea.
“There is a lot of focus on reducing antibiotic use in humans and animals. This is of course important, but our study shows that we also need to pay attention to our waste streams, as this seems to be a place where new variants of antibiotic resistance could emerge,” concludes Fanny Berglund.
Reference: “Evidence for wastewaters as environments where mobile antibiotic resistance genes emerge” by Fanny Berglund, Stefan Ebmeyer, Erik Kristiansson and D. G. Joakim Larsson, 25 March 2023, Communications Biology.
DOI: 10.1038/s42003-023-04676-7
