Abstract: The effectiveness of antibiotic treatment was examined in a mouse model of Lyme borreliosis. Mice were treated with ceftriaxone or saline solution for one month, commencing during the early (three weeks) or chronic (four months) stages of infection with Borrelia burgdorferi. Tissues from mice were tested for infection by culture, PCR, xenodiagnosis, and transplantation of allografts at one and three months after completion of treatment.
In addition, tissues were examined for the presence of spirochetes by immunohistochemistry. In contrast to saline solution-treated mice, mice treated with antibiotic were consistently culture negative, but tissues from some of the mice remained PCR positive, and spirochetes could be visualized in collagen-rich tissues.
Furthermore, when some of the antibiotic-treated mice were fed on by Ixodes scapularis ticks (xenodiagnosis), spirochetes were acquired by the ticks, as determined based upon PCR results, and ticks from those cohorts transmitted spirochetes to naive SCID mice, which became PCR positive but culture negative. Results indicated that following antibiotic treatment, mice remained infected with non-dividing but infectious spirochetes, particularly when antibiotic treatment was commenced during the chronic stage of infection.
Hodzic E, et al. Persistence of Borrelia burgdorferi following Antibiotic Treatment in Mice. Antimicrob Agents Chemother. 2008;52(5):1728-36.