The effect of long-term intermittent trimethoprim/sulfamethoxazole treatment on recurrences of toxoplasmic retinochoroiditis

PURPOSE: To determine the effect of long-term intermittent trimethoprim/sulfamethoxazole treatment on recurrences of toxoplasmic retinochoroiditis. DESIGN: Prospective randomized open-labeled interventional clinical trial. METHODS: A total of 124 patients with a history of recurrent toxoplasmic retinochoroiditis were randomized to treatment with one tablet of trimethoprim (160 mg)/sulfamethoxazole (800 mg) (Bactrim F; Roche Pharmaceuticals, Rio de Janeiro, Brazil) every 3 days (61 patients) or to observation without treatment (63 patients) and were followed monthly for up to 20 consecutive months for clinical signs of disease recurrence. A recurrence was defined as a new focus of necrotizing retinochoroiditis with active inflammation either adjacent to or remote from preexisting retinochoroidal scars. RESULTS: Recurrences developed in four (6.6%) treated patients and in 15 (23.8%) controls (P =.01). Treatment was discontinued prematurely in four patients because of mild drug reactions. CONCLUSION: Long-term intermittent treatment with trimethoprim/sulfamethoxazole can reduce the rate of recurrent toxoplasmic retinochoroiditis.