Sewage Plants can be Breeding Grounds for 'Superbugs'

Researchers from Rice, Nankai and Tianjin universities have found that wastewater treatment plants in northern China revealed antibiotic resistant bacteria with dangerous multidrug-resistant gene compounds. These 'superbugs' could not be disinfected by chlorination, and contained levels of NDM-1 that are being released to the environment.

"It's scary," said lead study author from Rice University Pedro Alvarez, via a press release. He is an environmental engineer. "There's no antibiotic that can kill them. We only realized they exist just a little while ago when a Swedish man got infected in India, in New Delhi. Now, people are beginning to realize that more and more tourists trying to go to the upper waters of the Ganges River are getting these infections that cannot be treated.

"We often think about sewage treatment plants as a way to protect us, to get rid of all these disease-causing constituents in wastewater. But it turns out these microbes are growing. They're eating sewage, so they proliferate. In one wastewater treatment plant, we had four to five of these superbugs coming out for every one that came in."

Background information from the study notes that antibiotic-resistant bacteria has been a particularly dangerous problem for years that officials have noted in hospital environments. What makes it so worrisome is that it can be very hard to treat and harbors an encoding gene that makes much of it resistant to preventative measures.

Researchers analyzed antibiotic-resistant genes in extracellular and intracellular DNA from water and sediment that's applied to sites in the Haihe River basin in China, which drains an area of heavy antibiotic use. They found significant amounts of plasmids for weeks in river sediment that can invade throughout indigenous bacteria.

"It turns out that they transfer these genetic determinants for antibiotic resistance to indigenous bacteria in the environment, so they are not only proliferating within the wastewater treatment plant, they're also propagating and dispersing antibiotic resistance," Alvarez said, via the release. "This calls for us to take a look at these breeding grounds for antibiotic-resistant bacteria and how we might be able to create better barriers than chlorination."

More information regarding the study can be found via Environmental Science & Technology Letters.