Targeted Antibiotic Shows Promise Against Lyme

Researchers found that a neglected antibiotic called hygromycin A selectively kills Borelliella burgdorferi, the bacteria that cause Lyme disease. The antibiotic was able to treat Lyme disease in mice without disrupting the microbiome. Results of the NIAID-supported study appeared in Cell.

Treatment of Lyme disease entails the use of broad-spectrum antibiotics. These drugs kill the Lyme-causing bacteria but also kill many other bacteria types as well. As a result, they can damage the patient’s gut microbiome and select for resistance in non-target bacteria.

A team of researchers wanted to find an antibiotic that would kill B. burgdorferi while leaving other bacterial species alone. They suspected compounds that selectively kill B. burgdorferi might already exist in nature. To find out, they screened extracts from more than 450 soil bacteria. 

The researchers purified and identified a compound from this extract that acted against B. burgdorferi. It turned out to be hygromycin A, an antibiotic discovered in 1953. The team confirmed that hygromycin A did not kill most bacteria, including many beneficial gut microbes. But it did kill B. burgdorferi and other bacteria in the same class very effectively. Further investigation showed that B. burgdorferi took up the drug much more easily than other bacteria. 

Hygromycin A had no toxic effects on cultured human cells. In a mouse model of Lyme disease, 5 days of hygromycin A treatment cleared the infection as well as broad-spectrum antibiotics did but without disrupting the gut microbiome.

Hygromycin A baits could be used to clear the disease from wild mice. Since mice are the principal hosts of B. burgdorferi, this strategy might help to eradicate the disease at its source. More study will be needed before the compound can enter clinical trials.—Brian Doctrow, NIH Research Matters