Pneumocystis carinii pneumonia

Pneumocystis carinii pneumonia (PCP) is an opportunistic infection that has shown a marked increase in prevalence in the United States during the past 2 decades, particularly in association with aquired immune deficiency syndrome. Determining a specific taxonomy for P carinii has been problematic. The organism has greater homology with certain fungi than with certain protozoa, but unlike fungi, the cyst wall does not contain ergosterol or the characteristic protein elongation factor 3. Furthermore, several antifungal drugs have no effect against PCP, whereas the drugs with demonstrated anti-P carinii activity are antiprotozoan drugs. This article discusses briefly the transmission, epidemiology, pathogenesis, pathology, clinical manifestations, diagnosis, prognosis, treatment, and prevention of PCP.