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Wastewater treatment plants harbor antibiotic-resistant genes
Findings from a study conducted in seven European countries showed that the number of antibiotic-resistant genes found in wastewater treatment plants mirrored the prevalence of antibiotic-resistant genes in clinical isolates collected from patients.
“However, modern wastewater treatment plants seem to be able to eliminate antibiotic resistance efficiently,” Marko Virta, PhD, a lecturer in the department of microbiology at the University of Helsinki, told Infectious Disease News.
In light of “consistent observation of an increasing north-to-south clinical [antimicrobial resistance] prevalence in Europe,” Virta and colleagues compared antibiotic-resistant genes found in water flowing in and out of 12 urban wastewater treatment plants (UWTPs) in Cyprus, Finland, Germany, Ireland, Norway, Portugal and Spain. UWTPs “are among the most important receptors and sources of environmental” antibiotic resistance, they said. According to the study, the researchers analyzed 229 resistance genes and 25 mobile genetic elements.
Virta said antibiotic use in Europe varies widely by country.
“Overall, southern Europeans use much more antibiotics than their counterparts in the north,” he said. “Similarly, people living in the south of Europe tend to carry a much higher number of antibiotic-resistant bacteria than those living in northern Europe and that is seen in wastewaters.”
Specifically, Cyprus, Ireland, Portugal and Spain report relatively high rates of antibiotic use, whereas Finland, Germany and Norway report fewer antibiotic prescriptions and less antibiotic use.
This corresponds with findings from the study that showed more resistant genes were detected in wastewater bound for purification in Cyprus, Ireland, Portugal and Spain compared with the other three countries.
Although Virta said treatment plants are successful in eliminating resistance genes from most samples, the researchers found that the relative number of resistance genes increased during purification in one plant.
They recommended the implementation of regular surveillance and control measures for UWTPs.
“Further research should be done on a global scale and with more wastewater treatment plants in order to allow conclusions on the effect of type and characteristics of a wastewater treatment plants,” Virta said. – by Marley Ghizzone
Disclosures: The authors report no relevant financial disclosures.