Abstract
Pneumocystis jirovecii pneumonia (PcP) remains an important cause of morbimortality worldwide and a diagnostic challenge. Conventional methods have low accuracy, hardly discriminating colonization from infection, while some new high-cost or broncho-alveolar lavage-based methods have limited usefulness in developing countries. Quantitative PCR (qPCR) tests may overcome these limitations due to their high accuracy, possibility of automation, and decreasing cost. We evaluated an in-house qPCR targeting the fungus mtSSU gene using induced sputum. Sensitivity of the assay (ten target gene copies/assay) was determined using recombinant plasmids. We prospectively studied 86 AIDS patients with subacute respiratory symptoms in whom PcP was suspected. qPCR results were determined as quantification cycles (Cq) and compared with a qualitative PCR performed in the same IS, serum 1,3-β-D-Glucan assay, and a clinical/laboratory/radiology index for PcP. The qPCR clustered the patients in three groups: 32 with Cq ≤ 31 (qPCR+), 45 with Cq ≥ 33 (qPCR-), and nine with Cq between 31-33 (intermediary), which, combined with the other three analyses, enabled us to classify the groups as having PcP, not P. jirovecii-infected, and P. jirovecii-colonized, respectively. This molecular assay may contribute to improve PcP management, avoiding unnecessary treatments, and our knowledge of the natural history of this infection.
Highlights
Introduction iationsHIV is still an important cause of death across the world, [1] and Pneumocystis pneumonia (PcP) remains among the leading pulmonary opportunistic infections (OI) in several developing and developed countries [2,3,4,5,6,7]
We show here that our Quantitative PCR (qPCR), standardized for induced sputum (IS) samples, presents a high performance when applied to AIDS patients suspected of having Pneumocystis jirovecii pneumonia (PcP), allowing the discrimination between infection and colonization
We show here the results of a specific real-time PCR developed to quantify P. jirovecii in IS of AIDS patients suspected of having PcP who were prospectively admitted to our emergency unit
Summary
Introduction iationsHIV is still an important cause of death across the world, [1] and Pneumocystis pneumonia (PcP) remains among the leading pulmonary opportunistic infections (OI) in several developing and developed countries [2,3,4,5,6,7]. Data of PcP incidence are scarce mainly in developing countries, and the largest studies of invasive fungal infections (IFI). Seldom included PcP due to the difficulties related to its diagnosis [5,8,9,10,11,12,13]. In Brazil, it has been reported to range from 3.2% to 47.1% [14,15,16,17,18,19,20], and it is estimated that PcP accounts worldwide for almost 400,000 cases/year, with 200,000 deaths/year, mainly in developing countries [21]. PcP diagnosis remains a challenge, owing to several issues such as the absence of culture systems for P. jirovecii, low accuracy of the conventional diagnostic methods, and Licensee MDPI, Basel, Switzerland. Methods based on visualization of the fungus with conventional staining have low sensitivity, requiring broncho-alveolar lavage fluid (BALF)
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