Evaluation of different real time PCRs for the detection of Pneumocystis jirovecii DNA in formalin-fixed paraffin-embedded bronchoalveolar lavage samples.

The presence of Pneumocystis jirovecii in fresh clinical materials can be detected by PCR with high sensitivity and is thus preferred over microscopic methods. However, fresh materials are not always available, and on formalin-fixed paraffin-embedded materials, PCR may result in reduced detection rates. In this study the diagnostic sensitivity of P. jirovecii real time PCR on DNA isolated from fresh bronchoalveolar lavage (BAL) samples versus that from matched FFPE derived DNA is analyzed. Our results indicate that when targeting a small DNA fragment P. jirovecii PCR can be performed on FFPE BAL samples with acceptable sensitivity (up to 83.3%). This is considerably higher than the 33.3% positives observed by classical staining of these samples.