Comparison of 2 real-time PCR assays for diagnosis of Pneumocystis jirovecii pneumonia in human immunodeficiency virus (HIV) and non-HIV immunocompromised patients

• We investigated the ability of a commercial quantitative real-time PCR assay, the Bio-Evolution Pneumocystis jirovecii real-time PCR.
• Bio-Evolution Pneumocystis quantitative real-time PCR has shown comparable performances to an “in house” real-time PCR for PCP diagnosis.
• In contrast to the literature, lower sensitivity and specificity were found in this study, especially in non-HIV patients.
• Operational thresholds should be assessed according to underlying diseases and other clinical and radiological parameters.

A total of 120 bronchoalveolar lavage specimens from HIV and non-HIV immunocompromised patients, positive for Pneumocystis jirovecii by an “in house” real-time polymerase chain reaction (PCR), were evaluated by the Bio-Evolution Pneumocystis real-time PCR, a commercial quantitative assay. Patients were classified in 2 categories based on clinical and radiological findings: definite and unlikely Pneumocystis pneumonia (PCP). For the “in house” PCR, cycle threshold 34 was established as cut-off value to discriminate definite PCP from unlikely PCP with 65% and 85% of sensitivity and specificity, respectively. For the Bio-Evolution quantitative PCR, a cut-off value of 2.8 × 105 copies/mL was defined with 72% and 82% of sensitivity and specificity, respectively. Overlapped zones of results for definite and unlikely PCP were observed. Quantitative PCR is probably a useful tool for PCP diagnosis. However, for optimal management of PCP in non-HIV immunocompromised patients, operational thresholds should be assessed according to underlying diseases and other clinical and radiological parameters.