Enhanced diagnosis of Pneumocystis carinii: Promises and problems

Abstract

Over the past 20 yr, PCP has gone from a rather rare pathogen to the most common cause of pneumonia in immunocompromised patients. In response to this, sensitive and rapid staining methods have been developed for the detection of P. carinii and are in routine use in many clinical microbiology laboratories. In patients with a heavy organism burdens, such as those with AIDS, the diagnosis of PCP is often made by methods of specimen collection such as induced sputum and BAL that are less invasive than lung biopsy. PCR-based assays that are more sensitive than standard staining methods may allow for the diagnosis of PCP from induced sputum or BAL specimens in patients with low organism burdens, such as AIDS patients receiving prophylactic therapy for PCP, organ transplant recipients, or patients receiving chemotherapy. Future challenges include developing a PCR-based assay for routine use in the clinical microbiology laboratory that is sensitive enough to detect P. carinii in induced sputum and BAL specimens without compromising specificity.