Antibiotics are essential for fighting bacterial infection, but, paradoxically, they can also make the body more prone to infection and diarrohea by allowing gut pathogens to “breathe”, says a study.Antibiotics benefit pathogen growth by disrupting oxygen levels and fibre processing in the gut, the study said. The findings, published in the journal Cell Host Microbe, could lead to development of new strategies to prevent the side effects of antibiotic treatment. 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 the new research in a mouse model has identified the chain of events that occur within the gut lumen after antibiotic treatment that allow “bad” bugs to flourish. The process begins with antibiotics depleting “good” bacteria in the gut, including those that breakdown fibre from vegetables to create butyrate, an essential organic acid that cells lining the large intestine need as an energy source to absorb water, said lead researcher Andreas Baumler, professor at University of California Davis Health System in the US. The reduced ability to metabolise fibre prevents these cells from consuming oxygen, increasing oxygen levels in the gut lumen that favour the growth of Salmonella. Most persons infected with Salmonella develop diarrohea, fever, and abdominal cramps 12 to 72 hours after infection, according to the US Centres for Disease Control and Prevention (CDC). “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,” Baumler said. “In essence, antibiotics enabled pathogens in the gut to breathe,” Baumler noted.