C6 test as an indicator of therapy outcome for patients with localized or disseminated lyme borreliosis.

Management of Lyme disease would benefit from a test to assess therapy outcome. Such a test could be employed to ascertain if treatment of early Lyme disease was successful and would be helpful to clinicians assessing patients with lingering posttreatment symptoms. We reported recently that levels of the antibody to C(6), a Borrelia burgdorferi-derived peptide that is used as an antigen in the C(6)-Lyme diagnostic test, declined after successful antibiotic treatment of Lyme borreliosis patients. We assessed retrospectively the change in anti-C(6) antibody titers in 131 patients with either early localized disease (erythema migrans) or disseminated disease. All of these patients were treated with antibiotics and were free of the clinical signs shown at presentation within 12 weeks after the initiation of treatment. Decreases in reciprocal geometric mean titers (rGMT) of the anti-C(6) antibody were quantified for the subpopulation of 45 patients whose baseline rGMT were >/=80 and whose second serum specimens were obtained at least 6 months after the baseline specimen. Eighty percent of this patient group (36 of 45) experienced a >/=4-fold decrease in their rGMT (P < 0.0003). These results suggest that a change in the anti-C(6) antibody titer may serve as an indicator of therapy outcome for patients with localized or disseminated Lyme borreliosis.