A new study in Science Advances evaluated the normal body flora of a South American Yanomami tribe who had never interacted with Westerners before. The scientists swabbed the mouths, skin, and feces of 34 individuals, and sequenced the DNA of the bacteria living there. What they found was that the Yanomami group had the highest levels of microbial diversity ever reported in a human group. The villagers spend much time outdoors hunting and gathering, and have had almost no contact with the antibiotics and processed foods that come along with a Western lifestyle.
Study co-author Maria Gloria Dominguez-Bellosays says work suggests there may be a link between bacterial diversity, industrialized life, and diseases such as obesity, asthma, allergies, and diabetes. "We believe there is something environmental occurring in the past 30 years that is driving these diseases. We think the microbiome could be involved." William Hanage, a Harvard epidemiologist said” the relationship between the microbiome and human health is really complicated. Though we know that low bacterial diversity is associated with some modern illnesses, it’s not clear whether the low diversity causes the illness or vice versa. “It is a leap to say that more diverse is necessarily healthier,” says Hanage.
Another important finding was that, although the Yanomami microbes were susceptible to antibiotics, the bacteria carried antibiotic resistance genes. Since the Yanomami had never been exposed to Western culture, this means bacteria don’t need to be exposed to antibiotics to possess antibiotic resistance genes. Co-author Gautam Dantas said “A critical part of trying to curb the spread of antibiotic resistance is understanding where it comes from.
The new study concludes “Our work emphasizes the value of detailed characterization of microbiomes of people living ancestral life-styles, particularly if practices in industrialized societies might eradicate potentially beneficial microbes and their encoded functions. Characterization of the commensal resistome of diverse people will also inform the design and prudent deployment of antibiotics to minimize enrichment for preexisting resistance Causation and functional consequences of microbiome changes need to be understood before functional restoration of the microbiome is possible to attempt to reverse the current global trends in metabolic and inflammatory diseases."
The article can be found at: http://advances.sciencemag.org/content/1/3/e1500183