Sensitivity and Specificity of Plasma and Bronchoalveolar Lavage Fluid PCR for Diagnosing Pulmonary Mucormycosis in Subjects With Diabetes Mellitus

BackgroundMucorales polymerase chain reaction (PCR) is used to diagnose pulmonary mucormycosis (PM) among neutropenic individuals. However, data on the utility of PCR in patients with diabetes mellitus, another major risk factor for PM, are limited.ObjectiveThe primary objective was to assess the diagnostic performance of a commercial real‐time PCR assay (MucorGenius) in plasma and bronchoalveolar lavage fluid (BALF) for diagnosing PM (proven and probable cases only) in patients with suspected invasive mould disease (IMD). For the secondary objective, we evaluated the performance of the MucorGenius assay in all PM (proven, probable, and possible) cases.MethodsWe prospectively enrolled patients with suspected IMD and assessed the performance of MucorGenius PCR (index test) in plasma and BALF samples. A multidisciplinary team assigned the final diagnosis of IMD (reference standard) based on microscopy, histopathology, cytology, and culture. We report the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) with 95% confidence intervals (CI).ResultsWe enrolled 103 patients, of whom 43 (41.7%) were confirmed to have PM. Plasma PCR showed a sensitivity of 18.6% (95% CI: 8.4–33.4), specificity of 90.7% (95% CI:77.9–97.4), PPV of 66.7%, and NPV of 52.7%. Including possible PM/IMD cases improved the plasma PCR sensitivity to 30.0% (95% CI: 18.9–43.2) and retained specificity at 90.7%. BALF PCR had better sensitivity (47.4%) but poorer specificity (69.6%), with a PPV of 56.3% and NPV of 61.5%.ConclusionPlasma and BALF MucorGenius PCR have poor diagnostic performance for diagnosing PM among individuals with diabetes mellitus. Further multicenter studies are needed to validate these findings.