The diagnosis of mucormycosis by PCR in patients at risk: a systematic review and meta-analysis

Background: This systematic review and meta-analysis aimed to examine the performance of polymerase chain reaction (PCR) assays for diagnosing mucormycosis. Methods: A standardised search was conducted from conception to December 3rd 2024 using PubMed, Embase, Global Health, and Cochrane library. Original studies that used PCR-based methods on any human specimen to diagnose mucormycosis were analysed for eligibility. Using a bivariate meta-analysis, the diagnostic performance of PCR was examined against the European Organisation for Research and Treatment of Cancer–Mycoses Study Group Education and Research Consortium 2020 (EORTC-MSGERC) definitions of proven and probable invasive mould disease, which was modified to include all patients at risk of mucormycosis. The study protocol was registered on the PROSPERO database (CRD42023478667). Findings: Of 4855 articles, a total of 30 met inclusion criteria, including 5920 PCR reactions on 5147 non-duplicate specimens from 819 cases of proven/probable mucormycosis and 4266 patients who did not meet the EORTC-MSGERC 2020 criteria. According to specimen type, sensitivity of PCR varied (p < 0.001) whereas specificity was similar (p = 0.662). Bronchoalveolar lavage fluid offered the highest sensitivity of 97.5% (95% CI 83.7–99.7%), specificity of 95.8% (95% CI 89.6–98.4%), positive likelihood ratio (LR+) of 23.5, and negative likelihood ratio (LR−) of 0.03. Tissue provided sensitivity of 86.4% (95% CI 78.9–91.5%), specificity of 90.6% (95% CI 78.1–96.3%), LR+ of 9.2, and LR− of 0.15. Blood provided reduced sensitivity of 81.6% (95% CI 70.1–89.4%), specificity of 95.5% (95% CI 87.4–98.5%), DOR of 95, LR+ of 18.3, and LR− of 0.19. Formalin-fixed paraffin-embedded specimens yielded the lowest sensitivity of 73.0% (95% CI 61.0–82.3%), highest specificity of 96.4% (CI 95% 87.5–99.0%), LR+ of 20.2, and LR− of 0.28. The covariates best explaining heterogeneity of the overall analysis were specimen type, study design (cohort versus case-control) and disease prevalence while patient population (COVID-19 versus other) and PCR (conventional versus quantitative) had less impact on heterogeneity. Interpretation: This meta-analysis confirms the high performance of PCR for diagnosing mucormycosis and supports the instatement of PCR detection of free-DNA in blood, BALF and tissue into future updated definitions and diagnostic guidelines for mucormycosis. Funding: None.