Sewage and Superbugs

From Scientific American:

High levels of antibiotic resistance have been found in bacteria that live downstream from a waste-water treatment plant in Patancheru, near Hyderabad in India.

Two years ago, Joakim Larsson of the University of Gothenburg, Sweden, and his colleagues reported that the treatment plant released drugs in its effluent water at levels sometimes equivalent to the high doses that are given therapeutically. The antibiotic-containing water reaching the plant came from 90 bulk pharmaceutical manufacturers in the region, near Hyderabad, they determined. The researchers wondered what might be happening to bacteria in the environment exposed to these drugs. . . .

In three sites downstream of the plant, the resistance genes made up almost 2 percent of the DNA samples taken there, the researchers report in PLoS ONE. Because only one or two genes out of the typical genome of around 5,000 genes are necessary to protect the bacterium, that's a lot of genetic resistance, says Dave Ussery, a microbiologist at the Technical University of Denmark, who was not involved in the work.