The Darwinian treatment

A simultaneously frightening and fascinating Scientific American article highlights the findings of a study conducted by the University of Michigan's Chuanwu Xi to assess the impact that wastewater treatment plants may have on the evolution of antibiotic-resistant bacteria.  The authors document significant increases in the prevalence of antibiotic-resistant bacteria when comparing (1) treated effluent with raw influent, and (2) ambient water samples from sites downstream of the treatment plant to upstream sites.  The results suggest that treatment plants can create conditions wherein selective pressure favors the survival of bacteria that can withstand antibiotic treatment, and that these bugs may then be introduced into surface waters via wastewater effluent, where they have the potential to sicken those who contact the water through recreational activities like swimming and fishing.