Prospective randomized double blind placebo-controlled evaluation of azithromycin for treatment of cat-scratch disease.

OBJECTIVE: To determine the efficacy of azithromycin in the treatment of patients with typical cat-scratch disease.

DESIGN: Prospective, randomized, double blind, placebo-controlled clinical trial.

SETTING: Large military medical center and its referring clinics.

PATIENTS: Active duty military members and their dependents with laboratory-confirmed, clinically typical cat-scratch disease.

INTERVENTION: Study participants assigned by randomization to treatment with oral azithromycin or placebo for 5 days.

OUTCOME MEASURES: Lymph node volume was calculated using three dimensional ultrasonography at entry and at weekly intervals. The ultrasonographer was blinded to the treatment groups. Endpoint evaluations were predetermined as time in days to 80% resolution of the initial total lymph node volume.

RESULTS: Demographic and clinical data showed that the azithromycin and placebo treatment groups were comparable at entry although the placebo group tended to be older. Eighty percent decrease of initial lymph node volume was documented in 7 of 14 azithromycin-treated patients compared with 1 of 15 placebo-treated controls during the first 30 days of observation (P = 0.026). After 30 days there was no significant difference in rate or degree of resolution between the two groups.

CONCLUSIONS: Treatment of patients with typical cat-scratch disease with oral azithromycin for five days affords significant clinical benefit as measured by total decrease in lymph node volume within the first month of treatment.