Pneumocystis carinii: a deadly opportunist.

Pneumocystis carinii pneumonia is a life-threatening complication of diseases and therapies associated with immunosuppression. Approximately 80 percent of patients with acquired immunodeficiency syndrome will develop pneumocystis pneumonia. Diagnosis is important, because effective therapy is available. In most cases, diagnosis can be made by sputum analysis. Bronchoalveolar lavage will yield a diagnosis in 85 to 90 percent of patients with pneumocystis pneumonia, and is used when sputum induction and analysis is unproductive, unavailable or negative. Transbronchial biopsy and, rarely, open lung biopsy will yield the etiology of pneumonia in the remaining patients. Pentamidine or trimethoprim-sulfamethoxazole is the treatment of choice. Toxicity often occurs, including hypoglycemia, nephrotoxicity, neutropenia and rash. Corticosteroids are helpful in moderate to severe disease. Mortality for the first episode of P. carinii pneumonia averages 20 percent. Prophylaxis effectively prevents and reduces the incidence of future episodes.