In lab culture, Borrelia burgdorferi, the bacterium that causes Lyme disease, can survive amoxicillin treatment by transforming into a round-body form. Such round bodies persist in a slowly-growing state and are tolerant of antibiotics. In this study, the authors tested 1581 drugs that are already approved by the FDA, for antimicrobial activity against amoxicillin-induced round-bodied B. burgdorferi. They found 23 drugs with activity against the round bodies when used singly. In addition, they identified artemisinin, a malaria drug, in combination with cefoperazone and doxycycline, as well as sulfachlorpyridazine together with daptomycin and doxycycline as potent combinations that reduced round bodies. Importantly, these combinations also had some durable inhibitory effect, because re-growth after subculture was low. These findings provide evidence that the continued search for effective drug combinations against persister bacteria is warranted.
