India’s Ganges river is teeming with bacteria resistant to antibiotics
RIVER IS LIVING PROOF THAT ANTIBIOTIC-RESISTANT BACTERIA ARE ALMOST EVERYWHERE
We needed to find some place with clear differences between polluted and unpolluted areas ... That turned out to be the Ganges.” David W. Graham | Professor, Newcastle University
High in the Himalayas, it’s easy to see why the Ganges River is considered sacred.
According to Hindu legend, the Milky Way became this earthly body of water to wash away humanity’s sins. As it drains out of a glacier here, rock silt dyes the ice-cold torrent an opaque grey, but biologically, the river is pristine — free of bacteria.
Then, long before it flows past any big cities, hospitals, factories or farms, its purity degrades. It becomes filled with a virulent type of bacteria, resistant to common antibiotics.
The Ganges is living proof that antibiotic-resistant bacteria are almost everywhere. The river offers powerful insight into the prevalence and spread of drug-resistant infections, one of the world’s most pressing public health problems. Its waters provide clues to how these pathogens find their way into our ecosystem.
Winding over more than 2,400 kilometres to the Bay of Bengal, Ma Ganga — “Mother Ganges” — eventually becomes one of the planet’s most polluted rivers, a melange of urban sewage, animal waste, pesticides, fertilisers, industrial metals and rivulets of ashes from cremated bodies.
But annual tests by scientists at the Indian Institute of Technology show that antibiotic-resistant bacteria appear while the river is still flowing through the narrow gorges of the Himalayan foothills, hundreds of miles before it encounters any of the usual suspects that would pollute its waters with resistant germs.
The bacterial levels are “astronomically high,” said Shaikh Ziauddin Ahmad, a professor of biochemical engineering at the Indian Institute of Technology. The only possible source is humans, specifically the throngs of ritual bathers who come to wash away their sins and immerse themselves in the waters.
BUILDING RESISTANCE
Antibiotic-resistance genes are not new. They are nearly as old as life itself.
On a planet that is about 4.5 billion years old, bacteria appeared about 3.8 billion years ago. As they fed on one another — and later on moulds, fungi, plants and animals — their victims evolved genes to make bacteria-killing proteins or toxins, nature’s antibiotics. (Penicillin, for example, was discovered growing in mould.)
The bacteria, in turn, evolved defences to negate those antibiotics. What modern medicine has done, scientists say, is put constant Darwinian pressure on bacteria. Outside the body, they face sunlight, soap, heat, bleach, alcohol and iodine. Inside, they face multiple rounds of antibiotics. Only the ones that can evolve drug-resistance genes — or grab them from a nearby species, which some bacteria can do — will survive.
The result is a global bout of sudden-death elimination at a microscopic level. Bacteria once susceptible to all families of antibiotics have become resistant to penicillins, then tetracyclines, then cephalosporins, then fluoroquinolone — and so on, until nearly nothing works against them.
“When bacteria are stressed, they turn on their SOS system,” said David W. Graham, a professor of ecosystems engineering at Newcastle University in Britain and a pioneer in antibiotic-resistance testing. “It accelerates the rate at which they rearrange their genes and pick up new ones.”
Eight years ago, Ahmad, a former student of Graham, suggested testing Indian waters.
“Until then,” Graham said, “I had avoided India because I thought it was one huge polluted mess.” With antibiotic-resistant bacteria so ubiquitous, it would be hard to design a good experiment — one with a “control,” someplace relatively bacteria-free. “We needed to find some place with clear differences between polluted and unpolluted areas,” Graham said. “That turned out to be the Ganges.”
WORKING RIVER
Although it is officially sacred, the Ganges is also a vital, working river. Its numerous watersheds in the mountains, across the Deccan Plateau and its vast delta serve 400 million people — a third of India’s population — as a source of drinking water for humans and animals, essential for crop irrigation, travel and fishing.
Twice a year, two of Ahmad’s doctoral students, Deepak K. Prasad and Rishabh Shukla, take samples along the whole river, from Gangotri to the sea, and test them for organisms with drug-resistance genes.
The high levels discovered in the river’s lower stretches were no surprise. But the researchers found bacteria with resistance genes even in the river’s first 100 miles, after it leaves Gangotri and flows past the next cities downstream: Uttarkashi, Rishikesh and Haridwar.
More important, the researchers found that the levels were consistently low in winter and then surged during the pilgrimage season, May and June.
Tiny Gangotri is so high in the mountains that it closes in winter, made impassable by the snow. But in summer, the area’s population swells with hundreds of thousands of pilgrims.
The most famous of the Upper Ganges pilgrimage cities is Rishikesh. Its streets are lined with hotels with names like Holy River and Aloha on the Ganges. Besides pilgrims, Westerners pour in for the town’s annual yoga festival or to study in its many ashrams and ayurvedic medicine institutes.
CLEAN VS DIRTY
In 2014, Graham and Ahmad found the clean-versus-dirty line in the Ganges to be at its starkest at Rishikesh.
Upstream, the water was fairly clean both summer and winter, but downstream in summer, the levels of bacteria with drug-resistance genes were astounding. The levels of NDM-1 — a drug-resistance gene that was first discovered in India and whose first two initials stand for New Delhi — were 20 times higher.
That finding has led the researchers to several conclusions. The resistant bacteria in the water had to have come from people — specifically, from their intestines.
Perhaps more intriguing, those people were fairly healthy — most were hale and hearty enough to be pilgrims, yoga students or river-rafters.
Presumably, Ahmad and Graham explained, the healthy travellers’ “bad” gut flora were held in check by their “good” flora.
At least 1,000 bacterial species have been found colonising human intestines. A healthy individual has at least 150 species, all competing with one another for space and food.
People can shed the bacteria they carry into the Ganges, Ahmad’s and Graham’s research shows. Then, if someone else picks them up, then falls ill and is given antibiotics, the person’s good bacteria can be killed and the bad ones have an opportunity to take over.
Pilgrimage areas, Ahmad and Graham wrote, are “potential hot spots for antibiotic-resistance transmission at large scales.”
MATTER OF FAITH
In the meantime, pilgrims will continue to be at risk, trusting in the deities to protect them.
“Ganga is our mother — drinking her water is part of our faith,” said Jairam Bhai, a large, jovial 65-year-old food vendor who held two small jugs as he waited to descend into the water in Gangotri. “If you have faith, you are safe.”