Diagnosis of Pneumocystis carinii pneumonia: specificity and sensitivity of polymerase chain reaction in comparison with immunofluorescence in bronchoalveolar lavage specimens.

DNA amplification by the polymerase chain reaction (PCR) is a promising method for the detection of Pneumocystis carinii in immunosuppressed patients. The sensitivity and specificity of the PCR technique has been assessed in comparison with the immunofluorescence method (IF) on bronchoalveolar lavage fluid (BALF). Results correlated in 43 (78.8%) of 52 cases studied. P. carinii PCR gave positive results with BALF from all 32 patients found to have P. carinii pneumonia (PCP); IF gave positive results with 26 of them. PCR was more sensitive and as specific as IF. However, at the present time, we do not believe that it is clinically useful for detection of P. carinii in BALF samples. P. carinii DNA amplification by PCR should be reserved for testing IF-negative BALF samples from patients judged clinically to have PCP.