Study of Ganges River Highlights Growing Antibacterial Resistance

The Ganges River plays an important role in annual religious pilgrimages for millions of people in India, and researchers studying water quality in the Ganges during pilgrimage times have found it is 60 times more likely to spread bacterial "superbugs" than at other times of the year.

The research centered around pilgrimage sites in Rishikesh and Haridwar, which are in northern India along the banks of the Ganges. In May and June, hundreds of thousands of people travel to the region's sacred sites. During this time, a bacterial resistance gene is found in the water in significantly higher proportions.

"We studied pilgrimage areas because we suspected such locations would provide new information about resistance transmission via the environment. And it has -- temporary visitors from outside the region overload local waste handling systems, which seasonally reduces water quality at the normally pristine sites," said environmental engineer David Graham, an expert in environmental transmission of antibiotic resistance based at Newcastle University.

"The specific resistance gene we studied, called blaNDM-1, causes extreme multi-resistance in many bacteria, therefore we must understand how this gene spreads in the environment," Graham said. "If we can stem the spread of such antibiotic resistant genes locally -- possibly through improved sanitation and waste treatment -- we have a better chance of limiting their spread on larger scales, creating global solutions by solving local problems."

Graham and his team found that levels of blaNDM-1 in the Upper Ganges were 20 times higher per capita during the pilgrimage season than at other times. The researchers suspect that the influx of people to the sites during pilgrimage times causes sewage systems to become overloaded, resulting in untreated sewage being discharged directly into the river where pilgrims bathe.

"The bugs and their genes are carried in people's guts," Graham said. "If untreated wastes get into the water supply, resistance potential in the wastes can pass to the next person and spiraling increases in resistance can occur."

Worldwide, there is a growing concern surrounding bacteria that are resistant to a so-called "last resort" class of antibiotics called Carbapenems. There are few treatments for bacterial resistant to Carbapenems, and which makes their presence in water systems a great concern.

"This isn't a local problem -- it's a global one," Graham said. "What humans have done by excess use of antibiotics is accelerate the rate of evolution, creating a world of resistant strains that never existed before."

"Through the overuse of antibiotics, contamination of drinking water and other factors, we have exponentially speeded-up the rate at which superbugs might develop," he said.

"For example, when a new drug is developed, natural bacteria can rapidly adapt and become resistant; therefore very few new drugs are in the pipeline because it simply isn't cost-effective to make them.

"The only way we are going to win this fight is to understand all of the pathways that lead to antibiotic resistance. Clearly, improved antibiotic stewardship in medicine and agriculture is crucial, but understanding how resistance transmission occurs through our water supplies is also critical. We contend that improved waste management and water quality on a global scale is a key step."

Graham and his colleagues published their research in the journal Environmental Science & Technology.