A collaboration between researchers throughout Europe has found a correlation between antibiotic-resistant genes in wastewater and antibiotic consumption by patients in the region. The study was published in Science Advances and looked at water treatment plants in Finland, Norway, Germany, Ireland, Spain, Portugal and Cyprus.
It is important to evaluate the presence of antibiotic-resistant bacteria within our systems because of the risk of dispersion. If these bacteria were to make their way from wastewater into the environment and to the irrigation water used in agriculture, humans and wildlife alike would be gravely affected. This fear is particularly high as climate change-related weather events increase the frequency of flooding and overflow of water systems.
The results from this study have several conclusions, the first of which is that southern Europe uses more antibiotics than northern Europe. More specifically, antibiotic use is relatively high in Spain, Portugal, Cyprus, and Ireland, whereas in Finland, Norway and Germany antibiotics are prescribed and used less.
Perhaps unsurprisingly, people living in southern Europe also tend to carry a much higher number of antibiotic-resistant bacteria than those living in northern Europe; which is to say the Spaniards, the Portuguese, the Cypriots, and the Irish have more antibiotic-resistant bacteria than the Finns, the Norwegians, and the Germans.
Though every country participating in the study receives antibiotic-resistant genes into their wastewater treatment plants, Portugal, Spain, Cyprus, and Ireland did follow the above-described correlation, showing that more antibiotic-resistant genes enter treatment plants in southern Europe than in Finland, Norway, and Germany.
The upside of this investigation is that wastewater treatment plants were found to be quite effective overall. Apart from one Portuguese treatment facility where the relative number of antibiotic resistance genes increased during the purification process, the researchers found that treatment plants are largely able to rid the resistant genes from a majority of samples.
"In this study, 11 of the 12 wastewater treatment plants under investigation mitigated the resistance problem, which seems to indicate that modern plants work well in this regard," said Marko Virta, a University of Helsinki microbiologist from the Faculty of Agriculture and Forestry. "At the same time, an older plant or otherwise deficient purification process may end up increasing antibiotic resistance in the environment. We need more research findings from countries with high antibiotic consumption and less developed wastewater treatment practices." Virta and colleagues are hoping to conduct further research in Asia and West Africa in order to explain the anomaly in their results.
The team did find that the correlation was maintained for treated water leaving the treatment facilities. In other words, the higher the resistance in the incoming wastewater (southern European countries), the higher it remained in the water leaving the plant.