High Diagnostic Value of a New Real-Time Pneumocystis PCR from Bronchoalveolar Lavage in a Real-Life Clinical Setting

Abstract

Background: To diagnose Pneumocystis jirovecii pneumonia (PCP), PCR testing in bronchoalveolar lavage (BAL) fluid has recently become an alternative to immunofluorescence testing (IFT); however, its diagnostic accuracy is less clear. Objective: To analyze the diagnostic value of a new semiquantitative real-time PCR (RT-PCR) in BAL in a real-life clinical setting. Methods: Retrospective analysis of all RT-PCR results [semiquantitative: negative, weakly positive, and strongly positive; measured in cycle thresholds (Ct)] in BAL in the period between 2010 and 2014. The diagnosis of PCP was defined by clinical, radiological, and laboratory signs and by treatment initiation. Any positive PCR was compared with subsequent IFT. Results: Of 128 patient samples, 32 had PCP. There is a relevant correlation of high significance between positive PCR Ct and IFT (r = -0.7781, p < 0.001), which amounts to about 60% of the variance. Sensitivity, specificity, and positive predictive values (PPV) of any positive RT-PCR were 100, 80, and 63%, respectively. No patient with negative RT-PCR had PCP. Specificity and PPV are 100% in strongly positive RT-PCR, whereas they decrease to 80 and 21% in weakly positive RT-PCR. Conclusion: A negative RT-PCR (Ct >45) rules out PCP. A strongly positive PCR (Ct <31.5) confirms PCP. In these cases, the diagnostic value of the new method is at least equal to the IFT. A weakly positive PCR probably represents pneumocystis colonization and can occur under PCP treatment.

DNA‐based testing in lung transplant recipients with suspected non‐viral lower respiratory tract infection: A prospective observational study

“…Conventional microbiology testing by cultures is time consuming. DNA‐based testing through polymerase chain reactions (multiplex PCR) may provide a faster alternative and have proven benefits in detecting some pathogens such as Pneumocystis jirovecii . However, data regarding BAL detection of other lung pathogens in LTx recipients are lacking.…”

LOW CD4 LYMPHOCYTE COUNT RELATED RISK TO Pneumocystis jiroveci PNEUMONIA IN HIV/AIDS PATIENTS FROM BRONCHOALVEOLAR LAVAGE SPECIMENS USING REAL TIME PCR DETECTION

“…The less cycle the increasing of CT indicated the more targeted DNA load in the sample. 16 Cycle threshold value positively correlated with the microorganism density in the sample. 17 A cut off CT value of 32 cycle can be applied in differentiating colonization to P. jiroveci infection with sensitivity 72% and specificity 75%.…”

“…The P. jiroveci DNA can be detected even after prophylactic therapy but the microscopy examination can be difficult to achieve. 16 …”

Pneumocystis jirovecii Laboratuvar Tanısında Gerçek Zamanlı Polimeraz Zincir Reaksiyonu Yönteminin Değerlendirilmesi

“…Kantitasyon olanağı sunması nedeniyle kolonizasyon/enfeksiyon ayrımında fikir veriyor olması yöntemin birincil üstünlüğü olarak gösterilmektedir [22][23][24] . Uygulamasının kolay ve hızlı bir yöntem olmasının yanı sıra kapalı sistem olması nedeniyle dışarıdan kontaminasyon riskini en aza indirmesi, yöntemin diğer avantajları olarak öne çıkmaktadır 8,22,23,[25][26][27] .…”