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Even an Isolated Amazonian Tribe’s Microbes Are Antibiotic Resistant

The finding of antibiotic resistance in people who have never taken antibiotics highlights how hard it will be to combat superbugs

Several Yanomami at the community of Irotatheri, in Venezuela, wait to preform a dance for visiting journalists (Carlos Garcia Rawlins/Reuters/Corbis)
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Without effective antibiotics, illnesses that are easily treatable today could once again become killers. Recently, antibiotic resistance has cropped up and created 'superbugs' that don’t fall to doctors' best medicines. At fault is the overuse of antibiotics — by doctors who prescribe them when they aren’t needed and by farmers hoping to both prevent healthy animals from getting sick, and to make them grow faster.  

In general, these causes are associated with an industrialized, modern lifestyle, so you might expect that some places, far removed from modern medicine and farming, would be protected from the coming swarm of antibiotic resistant bacteria. But, as Ann Gibbons reported for Science, researchers recently found that the bacteria in the guts of a group of Yanomani, Amazonian hunter-gatherers who have long been isolated from modern medicine and diet, had antibiotic-resistant genes. 

The Yanomami live deep in the Amazon rainforest on the boarder between Venezuela and Brazil and while their presence was first noted in the mid 1700s, the group remained isolated from the outside world until the 1950s. In 2008, an army helicopter noted a previously uncontacted Yanomami tribe, and, Gibbons writes, researchers immediately requested permission to study them, "before they were exposed to Western medicines and diets and would, therefore, lose diverse microbes." A medical expedition visited a village in 2009, treating some children with respiratory infections and also collecting bacteria from the mouths, skin and feces of 34 people in the village, reports Gibbons

The new research revealed that the Yanomami gut and skin bacteria has higher diversity than other populations, the scientists report in Science Advances. Also, a look at bacterial genes showed that the Yanomani gut microbes had 60 unique genes that can fight against antibiotics, including a half-dozen genes that would help the bacteria resist synthetic antibiotics. Gibbons writes:

The medical team’s interviews with these Yanomami villagers found they were never given drugs or exposed to food or water with antibiotics. Instead, [microbiologist Gautam Dantas, of Washington University in St. Louis] suggests that the Yanomami gut bacteria have evolved an armory of methods to fight a wide range of toxins that threaten them—just as our ancestors and other primates have done to fight dangerous microbes. For example, the Yanomami bacteria may already have encountered toxins that occur naturally in their environment that are similar in molecular structure to modern antibiotics, but have yet to be discovered by scientists. Or, gut bacteria in humans have evolved a generalized mechanism for detecting certain features shared by all antibiotics—including the synthetic ones designed by scientists—and so can mount a defense against new threats.

The finding emphasizes the difficulty researchers and physicians will face in combating the growing danger of antibiotic resistance. It shows that “antibiotic resistance is ancient, diverse, and astonishingly widespread in nature—including within our own bodies,” anthropologist Christina Warinner of the University of Oklahoma in Norman, who wasn’t involved in the study, told Gibbons. “Such findings and their implications explain why antibiotic resistance was so quick to develop after the introduction of therapeutic antibiotics, and why we today should be very concerned about the proper use and management of antibiotics in both clinical and agricultural contexts.”

Research on the Yanomami hasn't been without controversy. A 2000, a book by journalist Patrick Tierney accused researchers of gathering blood samples from the tribe without proper consent. Tribal members felt as though they hadn't consented to the way the blood was being used, including the fact that samples twould be preserved indefinitely — a practice that runs counter to the Yanomami traditions of treating bodily remains after death.

Before this work, researchers already knew that antibiotic resistance didn't necessarily require contact with antibiotics or industrial famrs. Past work has found viruses with genes for antibiotic resistance in 14th century fossilized human poo, long before doctors started using antibiotics in medicine. After all, competition between microbes is how antibiotics and its counter — antibiotic resistance — evolved. When antibiotics show up in soil and even insect wings, antibiotic resistance will turn up too. Still, figuring out how such resistant bugs move into the human gut, where they can effect human health, is important. 

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