Pneumocystis carinii pneumonia. Problems in diagnosis and therapy in 24 cases.

Twenty-four instances of Pneumocystis carinii pneumonia were recognized in 23 patients at the Stanford University Hospitals between 1962 and 1970. The affected persons could be broadly characterized as "compromised" hosts. All but one were receiving immunosuppressive drug therapy for such underlying disease as hematopoietic malignant disease, collagen vascular disorder, and organ transplant rejection. The one patient not receiving immunosuppressant medication had congenital dysgammaglobulinemia and suffered two discrete bouts of pneumocystis pneumonia. Most of the patients were concomitantly infected with other "opportunistic" pathogens. Open lung biopsy remained the most reliable method of antemortem diagnosis of pneumocystis infection during this eight-year period. It resulted in little morbidity. Unfortunately, direct examination of appropriately stained sputum specimens for cysts was almost uniformly nonproductive. The majority of patients received specific antipneumocystis drug treatment (pentamidine isethionate or pyrimethamine and sulfadiazine). "Cure" was achieved when institution of therapy was prompt and duration of therapy approached the empirically recommended two-week course. The fact that pneumocystis pneumonia can be controlled if recognized early is compelling reason to pursue diagnosis of pneumocystosis in an appropriate clinical setting, namely, in patients with impaired host defenses who have pulmonary infection unresponsive to conventional therapy. There is hope that a noninvasive (serological) technique will be developed shortly to simplify identification of this not uncommon cause of diffuse interstitial pneumonitis.