β-D-Glucan and S-adenosylmethionine serum levels for the diagnosis of Pneumocystis pneumonia in HIV-negative Patients: A prospective study

Objective: To prospectively assess the diagnostic utility of S-adenosylmethionine (AdoMet) and (1 -> 3)-beta-D-glucan (beta-D-glucan) serum markers for Pneumocystis pneumonia (PCP) in HIV-negative patients. Methods: HIV-negative, immunocompromised patients suspected of PCP based on clinical presentation and chest imaging were included. PCP was confirmed or rejected by results of direct microscopy and/or real-time PCR on broncho-alveolar lavage (BAL) fluid. Measurement of serum beta-D-glucan and AdoMet was performed on serum samples collected at enrollment and during follow-up. Both serum beta-D-glucan and AdoMet were assessed for diagnostic accuracy and correlation with clinical and laboratory parameters. Results: In 31 patients enrolled (21 PCP-positive, 10 PCP-negative), AdoMet levels did not discriminate between patients with and without PCP. Elevated serum beta-D-glucan was a reliable indicator for PCP with a sensitivity of 0.90 and specificity of 0.89 at the 60 pg/ml cut-off. In PCP-positive patients beta-D-glucan serum levels decreased during treatment and inversely correlated with Pneumocystis PCR cycle threshold values in BAL fluid. Conclusions: The level of serum beta-D-glucan-but not AdoMet - was diagnostic for PCP within the clinical context and may serve as marker for pulmonary fungal load and treatment monitoring. (C) 2010 The British Infection Association. Published by Elsevier Ltd. All rights reserved.