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A look at our disappearing microbes

8146322408_5312e9deb2_zCould obesity, asthma, allergies, diabetes, and certain forms of cancer all share a common epidemiological origin? NYU microbiologist Martin Blaser, MD, thinks so – he calls these “modern plagues” and traces them to a diminished microbial presence in our bodies, caused by the overuse of antibiotics and the increased incidence of caesarian sections.

I attended a recent public lecture sponsored by UC Santa Cruz’s Microbiology and Environmental Toxicology department, during which the charismatic Blaser cited statistics about antibiotic use in childhood. Alarmingly, American children receive on average seventeen courses of antibiotics before they are twenty years old, taking a progressively bigger toll on their internal microbial ecosystems. We also have an unprecedented rate of c-sections - at nearly 33 percent. Babies delivered this way are deprived of contact with their mothers’ vaginal microbes, which in vaginal deliveries initiates the infant’s intestinal, respiratory, and skin flora. Breastfeeding has implications for beneficial bacterial transfer, too.

It’s not news that antibiotics are being overused – Stanford Medicine hosts an Antimicrobial Stewardship Program dedicated to this cause, and the CDC has been hosting a campaign for awareness about appropriate antibiotic use for several years, including their use in farm animals. (Seventy to eighty percent of antibiotic use takes place on farms to promote growth - that is, not for veterinary reasons.)

Overuse leads to antibiotic resistance, a serious problem. Meanwhile, research by Blaser and others – notably Stanford microbiologist David Relman, MD – has shown that abundant bacterial and viral life is essential to healthy bodies, and that imbalances in the microbial ecosystems that inhabit our gut play an important role in the chronic diseases of the modern age. Blaser said he is concerned that we’re going down a path where each generation has fewer and fewer species of microbes; part of his research is to compare human gut biodiversity in different parts of the globe, and people in remote areas of New Guinea have far more variety than those in Western nations.

The problem is not just within the Western medical community. For example, antibiotic use is significantly worse in China, where there are far fewer restrictions.

While antibiotics are known to be ineffective in many circumstances (for instance against viruses), they haven't typically been considered unsafe, so they've been given to patients when pressed for them.

During the question period at the end of the lecture, the audience was filled with curiosity about probiotics, fecal transplants and numerous other supposed microbe-replacement aids. Blaser's consistent response was that there is a lot that has not been tested, and that above all we need to do rigorous research to determine the actual effects of any of these, weeding out marketing hype and the placebo effect.

What else can be done? Blaser encouraged audience members to tell their politicians to fund research in this area. Healso advocated participating in the American Gut Project, a crowd-sourced gut-bacteria information gathering endeavor he called “wonderful.” (If you’re interested, check out preliminary results from the project, the related Human Food Project, and ponder some of the ethical concerns it raises).

Blaser is a professor of clinical pharmacology and microbiology at NYU, director of NYU’s Human Microbiome Project, and author of Missing Microbes: How the overuse of antibiotics is fueling our modern plagues.

Previously: Free online course aims to educate about ‘pressing public health threat’ of antibiotic resistance
Photo by Pacific Northwest National Laboratory

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