Inter-laboratory comparison of three different real-time PCR assays for the detection of Pneumocystis jiroveci in bronchoalveolar lavage fluid samples.

Pneumocystis jiroveci pneumonia (PCP) is an opportunistic infection affecting immunocompromised patients. While conventional diagnosis of PCP by microscopy is cumbersome, the use of PCR to diagnose PCP has great potential. Nevertheless, inter-laboratory validation and standardization of PCR assays is lacking. The aim of this study was to evaluate the inter-laboratory agreement of three independently developed real-time PCR assays for the detection of P. jiroveci in bronchoalveolar lavage fluid samples. Therefore, 124 samples were collected in three tertiary care laboratories (Leiden University Medical Center, Maastricht Infection Center and Radboud University Nijmegen Medical Centre) and were tested by both microscopy and real-time PCR. Of 41 samples positive for P. jiroveci by microscopy, 40 were positive in all three PCR assays. The remaining sample was positive in a single assay only. Out of 83 microscopy-negative samples, 69 were negative in all three PCR assays. The other 14 samples were found positive, either in all three assays (n=5), in two (n=2) or in one of the assays (n=7). The data demonstrate high inter-laboratory agreement among real-time PCR assays for the detection of P. jiroveci.