New therapies could stop antibiotic-induced damage to gut health

As many know, antibiotics help treat bacterial infections by destroying the harmful bacteria causing them. But they can also destroy the good bacteria found in the gut that support our immune system and overall well-being.

Most commonly, people develop recurrent Clostridiodes difficile infections and regular gastrointestinal (GI) problems. Additionally, people experience allergic reactions, metabolic, and inflammatory diseases. “Many antibiotics inhibit the growth of various pathogenic bacteria. This broad activity spectrum is useful when treating infections, but it increases the risk that the microbes in our gut are targeted as well,” explained Lisa Maier, DFG Emmy Noether group leader at the University of Tübingen, in a statement.

Researchers from the Typas group at EMBL Heidelberg, the Maier lab at the Cluster of Excellence ‘Controlling Microbes to Fight Infections’ at the University of Tübingen, and collaborators explored the effects of 144 antibiotics on the most common microbes in the gut, and the survival of 27 bacterial strains. In this study, the researchers determined the concentrations at which a specific antibiotic would affect certain strains for more than 800 antibiotic–strain combinations.

Their experiments show that close to half of the tested strains didn’t survive the treatments. They were surprised to find that two antibiotics — tetracycline and macrolides — which are only supposed to stop bacterial growth, actually killed the bacteria.

To explore possible ways of reducing this damage, the researchers also investigated whether certain drugs could mask the negative effects of antibiotics on healthy gut microbes, while allowing the antibiotic to run its course on pathogenic ones. “This would provide something like an antidote, which would reduce the collateral damage of antibiotics on gut bacteria,” says Typas.

To do this, the scientists combined either either erythromycin or doxycycline antibiotics with a set of 1,200 pharmaceuticals to identify drugs that would save two common gut bacterial species from damage. Their findings confirmed that non-antibiotic drugs could be saving graces for healthy gut microbes. “Our approach that combines antibiotics with a protective antidote could open new opportunities for reducing the harmful side effects of antibiotics on our gut microbiomes,” concludes Maier.

This study suggests a new approach to stopping adverse effects of antibiotic treatment in its tracks, which is a welcomed idea in scientific research since millions of Americans take them per years. The researchers recognize that there is a greater need for other studies to identify the most optimal dosing, combination, and antidote formulation. Future similar findings can pave the way for these medications to be applied in clinical settings and help maintain optimal gut health in patients, all while allowing antibiotics to do their job.

This study is published in the journal Nature.

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