Test performance of blood beta-glucan for Pneumocystis jirovecii pneumonia in patients with AIDS and respiratory symptoms
ABSTRACT OBJECTIVE:: The objective of this study was to define the test characteristics of plasma beta-glucan for diagnosis of Pneumocystis jirovecii pneumonia (PCP) in AIDS patients with respiratory symptoms. DESIGN:: Analysis of baseline blood samples in a randomized strategy study of patients with acute opportunistic infections, limited to participants with respiratory symptoms. METHODS:: Participants in the 282-person ACTG A5164 trial had baseline plasma samples assayed for beta-glucan testing. As part of A5164 trial, two study investigators independently adjudicated the diagnosis of PCP. Respiratory symptoms were identified by investigators from a list of all signs and symptoms with an onset or resolution in the 21 days prior to or 14 days following study entry. Beta-glucan was defined as positive if at least 80 pg/ml and negative if less than 80 pg/ml. RESULTS:: Of 252 study participants with a beta-glucan result, 159 had at least one respiratory symptom, 139 of whom had a diagnosis of PCP. The sensitivity of beta-glucan for PCP in participants with respiratory symptoms was 92.8% [95% confidence interval (CI) 87.2-96.5], and specificity 75.0% (95% CI 50.9-91.3). Among 134 individuals with positive beta-glucan and respiratory symptoms, 129 had PCP, for a positive predictive value of 96.3% (95% CI 91.5-98.8). Fifteen of 25 patients with a normal beta-glucan did not have PCP, for a negative predictive value of 60% (95% CI 38.7-78.9). CONCLUSION:: Elevated plasma beta-glucan has a high predictive value for diagnosis of PCP in AIDS patients with respiratory symptoms. We propose an algorithm for the use of beta-glucan as a diagnostic tool on the basis of the pretest probability of PCP in such patients.
- AIDS (London, England) 06/2013; 27(10):1679. DOI:10.1097/QAD.0b013e3283620831 · 6.56 Impact Factor
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ABSTRACT: This study assessed a quantitative PCR (qPCR) assay for Pneumocystis jirovecii (P.jirovecii) quantification in bronchoalveolar lavage (BAL) samples combined with serum (1→3)-β-D-glucan (BG) level detection to distinguish Pneumocystis pneumonia (PCP) and pulmonary colonization with P.jirovecii. Forty-six patients, for whom P.jirovecii was initially detected in BAL samples, were retrospectively enrolled. Based on clinical data and results of P.jirovecii detection, 17 and 29 patients were diagnosed with PCP and colonization, respectively. BAL samples were re-assayed using a qPCR assay targeting the mitochondrial large subunit rRNA gene. qPCR results and serum BG levels (Fungitell® kit) were analyzed conjointly. P.jirovecii DNA copy number was significantly higher in the PCP group than in the colonization group (1.3x10(7) vs. 3.4x10(3) copies/μL, p<0.05). A lower cut-off value (1.6x10(3) copies/μL) achieving 100% sensitivity for PCP diagnosis and an upper cut-off value (2x10(4) copies/μL) achieving 100% specificity were determined. Applying these two values, 13/17 PCP patients and 19/29 colonized patients were correctly assigned to their patient groups. For the remaining 14 patients for whom P.jirovecii DNA copy number ranged between the cut-off values, the diagnoses of PCP and colonization were not distinguished on the basis of qPCR results. Four of these patients, initially assigned to the PCP group, presented a BG level ≥100 pg/mL. The other 10 patients, initially assigned to the colonization group, presented a BG level <100 pg/mL. These results suggest that the combination of qPCR assay, applying 1.6x10(3) and 2x10(4) copies/μL cut-offs, and serum BG detection, applying a 100 pg/mL threshold, discriminates PCP and colonization diagnoses.Journal of clinical microbiology 07/2013; 51(10). DOI:10.1128/JCM.01554-13 · 4.23 Impact Factor
- AIDS (London, England) 11/2013; 27(18):2967-2968. DOI:10.1097/QAD.0000000000000018 · 6.56 Impact Factor