Pneumocystis carinii Pneumonia

Abstract

The development of immunosuppressive and antineoplastic chemotherapy and the improved survival of immunodeficient patients have brought about an increase in Pneumocystis carinii pneumonia (PCP), an opportunistic, generally fatal protozoan infection if untreated. The infection is confined to the lungs and manifests clinically as severe interstitial pneumonia with alveolar-capillary block and hypoxia. Onset is insidious, with an initial nonproductive cough progressing to severe respiratory decompensation over 3 to 6 weeks. Diagnosed by sputum smears and transbronchial biopsies, the organism responds well to treatment. Pentamidine, 4 mg/kg body-weight/day IM for 14 days, is highly effective but is associated with a high incidence of toxicity, notably nephrotoxicity. The combination of trimethoprim and sulfamethoxazole, 20 mg and 100 mg/kg body-weight/day, respectively, in divided doses for 14 days, shows clinical promise with less toxicity.