New Study Finds That Even The Cleanest Wastewater Contributes To More 'Super Bacteria'

A new University of Minnesota study reveals that treated municipal wastewater -- even wastewater treated by the highest-quality treatment technology -- can result in significant quantities of antibiotic-resistant bacteria, often referred to as "superbacteria," in surface waters. The study also suggests that standard wastewater treatment technologies probably release far greater quantities of antibiotic-resistant genes used by bacteria, but this likely goes unnoticed because background levels of bacteria are normally much higher than in the water studied in this research.

The new study is led by civil engineering associate professor Timothy LaPara in the University of Minnesota, Twin Cities College of Science and Engineering. The study is published in the most recent issue of Environmental Science and Technology, a journal of the American Chemical Society. The research was part of a unique class project in a graduate-level civil engineering class at the University of Minnesota focused on environmental microbiology.

Antibiotics are used to treat numerous bacterial infections, but the ever-increasing presence of antibiotic-resistant bacteria has raised substantial concern about the future effectiveness of antibiotics. In response, there has been increasing focus on environmental reservoirs of antibiotic resistance over the past several years. Antibiotic use in agriculture has been heavily scrutinized, while the role of treated municipal wastewater has received little attention as a reservoir of resistance.

Antibiotic-resistant bacteria develop in the gastrointestinal tracts of people taking antibiotics. These bacteria are then shed during defecation, which is collected by the existing sewer infrastructure and passed through a municipal wastewater treatment facility.