Sulfamethoxazole-Trimethoprim Versus Ampicillin in Treatment of Shigellosis

Thirty-five infants and children hospitalized for severe shigellosis were randomly treated either with ampicillin or with sulfamethoxazole-trimethoprim for five days. Among the 35 isolated Shigella strains, 31 were S. sonnei (88%) and 4 were S. flexneri (12%), and 31.4% of the total strains, were ampicillin resistant. Fifteen patients treated with sulfamethoxazole-trimethoprim and 14 patients with ampicillinsusceptible Shigella treated with ampicillin responded comparably well to the therapy. Five of the patients successfully treated with sulfamethoxazole-trimethoprim had ampicillin-resistant Shigella infection. Three of them failed to respond to ampicillin during the first 72 hours of therapy but subsequently responded to sulfamethoxazole-trimethoprim. In vitro susceptibility studies showed good synergistic effects of sulfamethoxazole and trimelhoprim against the Shigella isolated. Judged from the present in vitro susceptibility studies and clinical experiences sulfamethoxazole-trimethoprim appears to be a highly effective drug in treating patients with shigellosis and the drug of choice in areas where ampicillin-resistant Shigella infection is common.