Efficacy of short-course ceftriaxone therapy for Borrelia burgdorferi infection in C3H mice

Abstract

Ceftriaxone is highly effective clinically in patients with Lyme disease. We studied a representative invasive human isolate of Borrelia burgdorferi for which the MBC of ceftriaxone was 0.050 microg/ml. A once-per-day dosage regimen of ceftriaxone (50 mg/kg/dose) administered intramuscularly for 5 days was 100% effective in sterilizing tissue samples of C3H mice infected with this strain of B. burgdorferi, regardless of whether the mice were being treated concomitantly with a corticosteroid. Administration of the same five doses of ceftriaxone at 6-h intervals over just 24 h was also 100% effective. These experiments suggest that shorter courses of antibiotics than those currently recommended should be considered for study in patients with early uncomplicated Lyme disease.

FIG. 1.

Ceftriaxone levels in the plasma of C3H mice at various time points after administration of the fifth and last dose of ceftriaxone (50 mg/kg given intramuscularly every 6 h). The mean ceftriaxone level and the standard error are plotted for each time point.