A new study from researchers at the Johns Hopkins Bloomberg School of Public Health found that a slow-growing variant form of Lyme bacteria caused severe symptoms in a mouse model. The slow-growing variant form of Lyme bacteria, according to the researchers, may account for the persistent symptoms seen in ten to twenty percent of Lyme patients that are not cured by the current Lyme antibiotic treatment.
The study, published March 28 in Discovery Medicine, also found that these “persister” Lyme bacteria were resistant to standard single-antibiotic Lyme treatments currently used to treat Lyme patients, while a three-antibiotic cocktail eradicated the Lyme bacteria in the mouse model.
For their study, the scientists isolated slow-growth forms of the Lyme bacterium, Borrelia burgdorferi. They found that, compared to normal fast-growth forms, the slow-growing forms caused more severe arthritis-like symptoms and resisted standard antibiotic treatment in test tube as well as in a mouse model. The scientists found that a combination of three antibiotics—daptomycin, doxycycline and ceftriaxone—cleared the Lyme infection in the study mice. The scientists now hope to test the combination in people with persistent Lyme disease.
“There is a lot of excitement in the field, because we now have not only a plausible explanation but also a potential solution for patients who suffer from persistent Lyme disease symptoms despite standard single-antibiotic treatment,” says study senior author Ying Zhang, MD, PhD, professor in the Department of Molecular Microbiology and Immunology at the Bloomberg School.
Lyme disease afflicts about 300,000 people in the United States every year. It is caused by Borrelia bacteria that live inside common species of ticks and are transmitted to humans by tick bites. Treatment with a single antibiotic—either doxycycline, amoxicillin or cefuroxime—for two to four weeks clears infection and resolves symptoms in most patients. However, some 10 to 20 percent of Lyme patients who are treated continue to suffer persistent symptoms including fatigue, muscle and joint aches, and brain fog that can six months or longer.