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Wastewater may be key to antibiotic resistance

Wastewater treatment plants have a role to play in reducing the spread of antibiotic-resistant bacteria.

While an increasing number of the dangerous bacteria is being found in waterways around the globe, a new study from the National University of Ireland shows effective wastewater treatment could help reduce the threat.

“Analytical data from our study indicates unequivocally that the total number of antimicrobial resistant E. coli is greatly reduced by wastewater treatment even if the proportion is somewhat increased,” said one of the report's authors, Dearbháile Morris.

“[But] wastewater treatment plants were not designed to specifically remove antibiotics and antibiotic-resistant bacteria.”

As a result, some antimicrobial-resistant (AMR) bacteria survive and are discharged into the environment.

With infections associated with AMR bacteria resulting in significant increases in health care costs, morbidity and mortality, the World Health Organisation is drafting a Global Action Plan for combating the threat.

Morris said further research into wastewater and sewage treatment was needed.

“A better understanding of the impact of current water treatment technologies and their ability to reduce/remove antibiotics and antibiotic resistant bacteria would contribute greatly to our understanding of the role the environment plays in the emergence and dissemination of antibiotic resistance,” she said.

“There is a need for further research to understand how the secondary wastewater treatment process may impact on the development of antimicrobial resistance; in particular what drives the development of resistance in effluent and what helps to maintain it.”

The study named a number of treatments that had been found to be effective.

“Advanced methods for treatment of hospital wastewaters, such as by reverse osmosis, using activated carbon or by ozonation, reduce or eliminate antimicrobials,” the report stated.

“Reducing sludge spreading is another possible method for decreasing the level of antimicrobials entering the waterways.”

“[Previous research has] credited oxidation with ozone or chlorine species as having the highest capacity for the removal of antimicrobial agents from surface and spiked distilled waters.

“These authors also identified that minimal antimicrobial removal occurs through coagulation, flocculation, sedimentation or excess lime softening, a chemical process that converts calcium and magnesium in water to calcium carbonate and magnesium hydroxide.”