Lyme disease treated with antibiotic that doesn’t harm gut microbiome
Mice overcame a Lyme disease infection after being given an antibiotic that is often used for pneumonia, and its effect on their gut microbiomes was negligible
By Carissa Wong
23 April 2025
Lyme disease can spread to people via ticks
Heiko Barth/Shutterstock
An antibiotic that is commonly used to treat pneumonia rid mice of Lyme disease at a dose 100 times lower than the standard antibiotic therapy. This smaller dose, combined with the drug’s targeted action against the infection, meant the animals’ gut microbiomes were largely unaffected.
Lyme disease is caused by bacteria in the genus Borrelia that mainly spread among birds and small rodents, but people can get infected via the bites of ticks that have fed on the blood of such animals. Infections commonly lead to flu-like symptoms and a “bull’s-eye” rash. If untreated, they can cause serious long-term complications, such as fatigue and aches.
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Standard treatment involves taking a high dose of the antibiotic doxycycline twice daily for up to three weeks. This stops bacteria from making the proteins they need to survive, but it doesn’t selectively target Borrelia species. “It wreaks havoc on the normal [gut] microbiome,” says Brandon Jutras at Northwestern University in Illinois.
Looking for a more selective alternative, Jutras and his colleagues first tested how effectively more than 450 antibiotics, all approved by the US Food and Drug Administration, could kill Borrelia burgdorferi – the most common type of Lyme disease-causing bacteria – in a lab dish.
They then assessed how the top-performing drugs affected the growth of harmless or beneficial bacteria that are commonly found in the guts of people and mice, such as certain strains of Escherichia coli. This revealed that piperacillin, an antibiotic that is related to penicillin and is commonly used to treat pneumonia, most selectively targeted B. burgdorferi.
