The effectiveness of antibiotic treatment was examined in a mouse model of Lyme borreliosis. Mice were treated with ceftriaxone or saline for one month, commencing during the early (3 weeks) or chronic (4 months) stages of infection with Borrelia burgdorferi
Tissues from mice were tested for infection by culture, polymerase chain reaction (PCR), xenodiagnosis, and transplantation of allografts at 1 and 3 months after completion of treatment. In addition, tissues were examined for spirochetes by immunohistochemistry.
In contrast to saline-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 upon by Ixodes scapularis ticks (xenodiagnosis), spirochetes were acquired by the ticks, based upon PCR,
And ticks from those cohorts transmitted spirochetes to naïve 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.
Source: Antimicrobial Agents and Chemotherapy, March 3, 2008. [E-pub ahead of print] PMID: 18316520, by Hodzic E, Feng S, Holden K, Freet KJ, Barthold SW. Center for Comparative Medicine, Schools of Medicine and Veterinary Medicine, University of California at Davis, Davis, California, USA. [E-mail: Stephen Barthold firstname.lastname@example.org ]