‘Superbugs’ spreading from water treatement plants

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E. Coli bacteria.

‘There’s no antibiotic that can kill them …’

By Summit Voice

FRISCO — Scientists already know that genetic mutations have made some bacteria resistant to antibiotics, and new research suggests that those superbugs are able to withstand purification efforts at water treatment plants. The bacteria are even multiplying in the very facilities meant to eliminate them.

“We often think about sewage treatment plants as a way to protect us, to get rid of all of these disease-causing constituents in wastewater,” said Rice University environmental engineer Pedro Alvarez, who led the recent study at two wastewater treatments plans in China. “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.”

The study found “superbugs” carrying New Delhi Metallo-beta-lactamase (NDM-1), a multidrug-resistant gene first identified in India in 2010, in wastewater disinfected by chlorination. They found significant levels of NDM-1 in the effluent released to the environment and even higher levels in dewatered sludge applied to soils.“It’s scary,” Alvarez said. “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.

Antibiotic-resistant bacteria have been raising alarms for years, particularly in hospital environments where public health officials fear they can be transferred from patient to patient and are very difficult to treat. Bacteria harboring the encoding gene that makes them resistant have been found on every continent except for Antarctica, the researchers wrote.

NDM-1 is able to make such common bacteria as E. coli, salmonella and K. pneumonias resistant to even the strongest available antibiotics. The only way to know one is infected is when symptoms associated with these bacteria fail to respond to antibiotics.

In experiments described in the same paper, Alvarez and his team confirmed the microbes treated by wastewater plants that still carried the resistant gene could transfer it via plasmids to otherwise benign bacteria.

“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,” he said. “I think we need to take a serious look at photo-disinfection processes, like ultraviolet disinfection. It has been shown to be more effective on resistant organisms. We also need a better understanding of how these microbes flow through the environment.”

Lead author Yi Luo is a professor of environmental sciences and engineering at Nankai University, Tianjin, China. Co-authors are Jacques Mathieu, a research scientist at Rice; graduate students Fengxia Yang and Qing Wang of Nankai University; and master’s student Daqing Mao of Tianjin University.

The National Natural Science Foundation of China, the State Environmental Protection commonweal project and the Ministry of Education Program for New Century Excellent Talents supported the research.

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