pneumocystosis /no̅o̅′mōsistō″sis/ [Gk, pneuma, air, kystis, bag, osis, condition] , infection with the fungus Pneumocystis jiroveci, usually seen in patients with human immunodeficiency virus infection; premature, malnourished infants; or debilitated or immunosuppressed people, particularly those with hematologic malignancies. It is characterized by fever, cough, tachypnea, and frequently cyanosis. The diagnosis is difficult to make and usually requires obtaining a specimen by an induced sputum procedure or bronchoalveolar lavage and special staining techniques. Mortality rates are near 100% in untreated patients. Treatment with pentamidine isethionate or a combination of trimethoprim and sulfamethoxazole, trimetrexate plus folic acid, trimethoprim plus dapsone, atovaquone, or primaquine plus clindamycin is effective. Patients at risk should receive prophylaxis against acute infection. Also called interstitial plasma cell pneumonia.
