A new semisynthetic
macrolide roxithromycin was evaluated for its potential use in the treatment of
Lyme borreliosis. Using a macro-dilution broth technique, Borrelia burgdorferi was shown to be susceptible to
roxithromycin with a minimal bactericidal concentration (MBC) of 0.06-0.25 microgram/ml. A systemic B. burgdorferi
infection was established in gerbils; a dosage of greater than or equal to 25 mg/kg/day
roxithromycin for 10 days eliminated the
infection. A single blind, randomized multicenter study was performed to evaluate the efficacy of
roxithromycin 150 mg b.i.d. versus
phenoxymethyl-penicillin 1 g b.i.d. for 10 days in patients with uncomplicated
erythema migrans. The study was interrupted when 19 patients had enrolled because of five treatment failures. All 5 patients had received
roxithromycin; three patients had persisting or recurrent
erythema migrans, one developed a secondary
erythema migrans-like lesion and severe
arthralgia and one developed neuroborreliosis. B. burgdorferi was isolated from skin biopsies after
roxithromycin therapy from two patients with persistent
erythema migrans and both isolates were still highly susceptible to
roxithromycin (MBC = 0.03 microgram/ml). No treatment failures were seen in 10 patients treated with
phenoxymethyl-penicillin.
Roxithromycin is thus not recommended for treatment of
Lyme borreliosis.