Septic systems may harbor antibiotic-resistant bacteria

A new housing development in Sun Prairie, Wis., is giving UW–Madison researchers a chance to test whether septic systems cause bacteria in groundwater to become resistant to antibiotics.

Led by UW–Madison environmental engineer Trina McMahon, the scientists are using new DNA-detection technology to test groundwater before and after the houses are built.

If the researchers detect any DNA associated with antibiotic resistance before the houses go in, the likelihood is that it originates from sources such as naturally occurring bacteria or bacterial runoff from agricultural lands, the scientists say.

If resistant bacterial DNA emerges after septic systems are in use, however, it would confirm the role of septic systems in contributing to the emergence of antibiotic-resistant bacteria.

The study is one of eight new projects related to drinking water, groundwater and surface water recently funded by UW–Madison’s Water Resources Institute.