An Indian river has turned into hotspot for dumped drugs. Drugs from a waste water treatment plant in Patancheru near Hyderabad is dumped into this river. The continual discharge of antibiotic-contaminated water has created a hotspot of bacterial antibiotic resistance in the river, reports Nature.
Two years ago, Joakim Larsson of the University of Gothenburg, Sweden, and his colleagues reported that the antibiotic-containing water reaching the plant came from 90 bulk pharmaceutical manufacturers in the region, near Hyderabad.
Bacteria can trade bundles of drug-resistance genes in mobile 'cassettes' carried, for example, on small circles of DNA called plasmids, which can replicate themselves independently of the bacterium's chromosome.
In three sites downstream of the plant, the resistance genes made up almost 2 percent of the DNA samples taken there, the team found.
According to Dave Ussery, a microbiologist at the Technical University of Denmark, 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.
Finding resistance amid so much exposure to active drug ingredients "is not surprising," said David Graham at Newcastle University, UK, who has studied sites in Cuba.
"But in a way, it's sort of like a beaker experiment," he said that tests the worst-case scenario, only this is "in a natural system. That's what makes it useful".
Bjorn Olsen, an infectious-disease specialist at Uppsala University in Sweden, said the resistance hotspots like the one at Patancheru could end up behaving like a volcanic eruption: "the cloud is going to drop down somewhere else, not just around the sewage plant".
Ussery cautioned that even if the bacteria found are not dangerous to humans or other animals in the area, they may transfer their resistance genes to bacteria that are.
"They need to know who's there," said Ussery, to identify which species are surviving and which are the sources of genetic resistance.