Antibiotics allow gut pathogens to 'breathe'

http://www.eurekalert.org/pub_releases/2016-05/uoc--aag050216.php

Public Release: 2-May-2016
Antibiotics allow gut pathogens to 'breathe'
UC Davis study details how antibiotics benefit pathogen growth by disrupting oxygen levels, fiber processing in the gut
University of California - Davis Health System

Antibiotics are essential for fighting bacterial infection, but, paradoxically, they can also make the body more prone to infection and diarrhea.

Exactly how the resident "good" microbes in the gut protect against pathogens, such as Salmonella, and how antibiotic treatments foster growth of disease-causing microbes have been poorly understood.

But research in a mouse model led by Andreas Bäumler, professor of medical immunology and microbiology at UC Davis Health System, has identified the chain of events that occur within the gut lumen after antibiotic treatment that allow "bad" bugs to flourish.

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According to Bäumler, the process begins with antibiotics depleting "good" bacteria in the gut, including those that breakdown fiber from vegetables to create butyrate, an essential organic acid that cells lining the large intestine need as an energy source to absorb water. The reduced ability to metabolize fiber prevents these cells from consuming oxygen, increasing oxygen levels in the gut lumen that favor the growth of Salmonella.

"Unlike Clostridia and other beneficial microbes in the gut, which grow anaerobically, or in the complete absence of oxygen, Salmonella flourished in the newly created oxygen-rich micro environment after antibiotic treatment," Bäumler said. "In essence, antibiotics enabled pathogens in the gut to breathe."

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