Treatment of Infection Due to Pneumocystis carinii

Abstract

The therapy of infection due to Pneumocystis carinii has evolved in two areas over the past 20 years. First, improve- ments in the diagnosis of Pneumocystis infection have facili- tated early diagnosis; treatment can often be initiated before marked deterioration in pulmonary function is observed. Sec- ond, the prolonged survival of immunocompromised patients has altered the presentation of Pneumocystis pneumonia, with there being an increased incidence of patients presenting with, in addition to P. carinii, multiple opportunistic infections often with some degree of resistance to common antimicrobial agents; the development of atypical (e.g., extrapulmonary) pre- sentations of disease; and a growing number of patients re- quiring alternative prophylactic regimens due to drug toxicity (19a). Because Pneumocystis infection can be rapidly progres- sive and the success of therapy is related to the severity of disease at the time of the initiation of therapy, early therapy is essential. The short-term use of treatment (48 h) will not impair the histopathologic diagnosis of infection if, for exam- ple, bronchoscopic or laboratory support services are tempo- rarily unavailable. The risk of opportunistic infection may be reduced by decreasing the level of immune suppression in patients receiving exogenous immune suppression for autoim- mune diseases or following organ transplantation or by de- creasing the viral load in patients infected with human immu- nodeficiency virus (HIV). Treatment of Pneumocystis should be successful if a 14- to 21-day course of therapy is tolerated.