Diagnostic strategies in Pneumocystis carinii pneumonia.

Pneumocystis carinii (P. carinii) remains a major pulmonary pathogen for the immunocompromised patient. In HIV infected patients, P. carinii represents the most commonly diagnosed cause of pneumonia. In the AIDS patient, empiric therapy based on clinical presentation has its proponents. However, this approach has been associated with a worse overall prognosis for the at risk patient. Because P. carinii can not be cultured, specific identification relies on examining respiratory specimens ranging from expectorated sputum to bronchoscopy with bronchoalveolar lavage (BAL). The low sensitivity of conventional stains has led to the search for antibodies to P. carinii and the use of immunofluorescent techniques. In addition, the polymerase chain reaction (PCR) is successfully being used in the diagnosis of P. carinii. Overall, these techniques allow the clinician to tailor the diagnostic testing for the individual patient.