Antibiotic-resistant bacteria are one of the major threats to healthcare. But it’s not just hospitals that are hotspots for resistant germs, as researchers have now discovered. The surface water of the Baltic Sea could also serve as a reservoir for antibiotic-resistant bacteria such as Escherichia coli. Resistant strains were detected at three measuring points. However, there is no danger for healthy bathers.
Antibiotics have revolutionized modern medicine and curbed numerous serious infectious diseases. But more and more bacteria that are resistant to antibiotics are spreading around the world, making it more difficult for those affected to heal. Hospitals are considered hotspots for the emergence and spread of such multi-resistant germs, but there could also be reservoirs in nature in which the dangerous pathogens accumulate. For example, you could get there via untreated wastewater.
Looking for resistance in the Baltic Sea
In this context, the Baltic Sea in particular would be a suitable reservoir for resistant germs. Due to its semi-enclosed nature, limited connections to other bodies of water, shallow depth and slow water exchange, various pollutants can accumulate in the Baltic Sea. But does this really also apply to resistant bacteria?
To find out, researchers led by Phillip Lübcke from the University of Greifswald took more than 120 water samples over a year at various locations in Greifswald and the surrounding area: including in a bathing area, near sewage treatment plants and in a protected area on the island of Riems . The team examined these samples for resistant Escherichia coli bacteria. These make themselves felt by producing certain enzymes that can break down important antibiotic ingredients.
Resistant pathogens and antibiotic residues detected
The result: Lübcke and his colleagues were able to detect a total of 30 E. coli isolates that produce such enzymes in the Baltic Sea water sampled. They found larger amounts of multi-resistant pathogens and antibiotic residues, particularly in the samples from sewage treatment plants. “Our results show that some of the isolated bacteria are considered high-risk strains and have significant resistance to important antibiotics,” explains senior author Katharina Schaufler from the Helmholtz Center for Infection Research. However, she emphasizes that there is no increased risk of becoming infected with resistant bacteria for healthy bathers with a normal immune system in the waters examined. “Our study serves to educate and is not intended to stir up fears,” says the microbiologist.
However, according to Schaufler, the results illustrate how difficult it is for sewage treatment plants to completely remove resistant bacteria and drug residues from the water. “It would be desirable to further optimize wastewater treatment processes in order to keep the burden of resistant bacteria and antibiotic residues as low as possible,” says Schaufler. At the same time, according to her, the use of antibiotics and antimicrobial drugs in medicine and agriculture should be regulated more specifically so that so many germs cannot reach sewage treatment plants in the first place.
Source: University of Greifswald; Specialist article: npj Clean Water, doi: 10.1038/s41545-024-00394-7