Efficacy of antibiotic prophylaxis for prevention of Lyme disease

OBJECTIVE: To determine if antibiotic prophylaxis following a deer tick bite is effective in reducing the risk of developing Lyme disease. DESIGN: Meta-analysis of published trials. DATA IDENTIFICATION: Clinical trials were identified by a computerized literature search of MEDLINE and by an assessment of the bibliographies of published studies. STUDY SELECTION: Trials were included in the analysis if their patients were randomly allocated to a treatment or control group, enrolled within 72 hours following an Ixodes tick bite, and had no clinical evidence of Lyme disease at enrollment. Three trials were selected for review after inclusion criteria were applied. DATA EXTRACTION: Data were extracted for details of study design, patient characteristics, interventions, duration of therapy, and number of adverse events in each arm of therapy. RESULTS OF DATA SYNTHESIS: Among the 600 patients with Ixodes tick bites, the rate of infection in the placebo group was 1.4%. In contrast, patients who received antibiotic prophylaxis had a 0% infection rate. The pooled odds ratio, comparing prophylaxis to placebo, was 0.0 (95% confidence interval 0.0, 1.5) (p = .12). CONCLUSIONS: The available evidence to date suggests that the routine use of antibiotic prophylaxis for the prevention of Lyme disease remains uncertain. Mete-analysis of the controlled trials failed to establish definitive treatment efficacy owing to the small sample size of the combined trials and the low rates of infection following a deer tick bite, A larger randomized trial is needed to demonstrate definitively that prophylaxis is more effective than placebo in reducing the risk of early Lyme disease in endemic areas.