Deep in the remote Amazonian jungles in Venezuela lives an isolated tribe of Yanomami Amerindians who offer a key to "our microbial past," according to Jose C. Clemente, PhD, assistant professor of genetics and genomics at the Icahn School of Medicine at Mount Sinai in New York City.
Dr. Clemente is the first author of a study that examined the microbial diversity in the isolated tribe. The study is the result of a collaborative effort with Icahn scientists and a multicenter team of U.S. and Venezuelan researchers.
The study found bacterial diversity in the Yanomami people — who were previously unexposed to antibiotics or industrialized diets — was nearly double that of people living in industrialized countries. The Yanomami people's bacterial diversity was also significantly higher than in other remote populations moderately exposed to modern practices.
The results indicate a link between antibiotic usage or western diet to the reduced bacterial diversity observed in modern societies. The findings also suggest that this loss of diversity happens quickly upon initial exposure to those practices.
"Even minimal exposure to these practices greatly decreases diversity and removes potentially beneficial bacteria from our microbiome," said Dr. Clemente.
Additionally, the scientists analyzed the gut and oral bacteria of the tribal people, revealing the villagers had bacteria encoding genes resistant to both natural and synthetic antibiotics, despite their lack of previous exposure to antibiotics.
"During the 1940s and 1950s, in the heyday of pharmaceutical antibiotic development, most antibiotics were derived from naturally occurring bacteria in the soil," said co-author Gautam Dantas, PhD, associate professor of pathology, immunology, and biomedical engineering at Washington University School of Medicine in St. Louis. "So, we would expect that natural resistance to antibiotics would emerge over millions of years of evolution. We didn't expect to find resistance to modern synthetic antibiotics."
Dr. Dantas noted that the presence of resistant genes in human microbes unexposed to antibiotics may help explain the rapid rate at which bacteria develop resistance to new classes of antibiotics.
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