Prevention of pneumocystis pneumonia. Use of continuous sulfamethoxazole-trimethroprim therapy.

Owing to a 15% attack rate of Pneumocystis carinii pneumonitis (PCP) among the leukemic population of Riley Hospital, Indianapolis, a two-year study using continuous low-dosage sulfamethoxazole-trimethoprim to prevent PCP was started in January 1977. A total of 229 pediatric cancer patients considered at high risk for getting PCP received prophylaxis, while 19 additonal low-risk cancer patients did not receive sulfamethoxazole-trimethoprim. None of these 248 patients contracted PCP. However, five cases of PCP did occur among ten additional high-risk patients who failed to receive this preparation for a variety of reasons. Complications of the continuous prophylaxis program included neutropenia, rash, and gastrointestinal complaints. This study confirms that continuous, low-dosage sulfamethoxazole-trimethoprim prophylaxis is effective in preventing PCP in susceptible immunosuppressed patients but is ineffective in eradicating the organism from the population at risk.