Real burden of mucormycosis diagnosed over five years in a French medical center: a retrospective study

Mucormycosis, a rare but fatal invasive fungal infection, affects immunocompromised patients. Despite recent advancements in diagnostic tools and treatments, mortality rates remain high, reaching 79% at ninety days in disseminated forms. Quantitative Polymerase Chain Reaction (qPCR) based methods are now widely available, and help to discern colonisation and infection, although this remains a real challenge. This study aims to describe the epidemiological and clinical characteristics of a French cohort of patients with presence of Mucorales in clinical samples. With a retrospective monocentric study from 2017 to 2022, we investigated risk factors associated with proven or probable mucormycosis and in-hospital mortality. Patients included had at least one Mucorale-positive culture, or positive PCR assay detecting Mucorales. Clinical, microbiological, and hospital management data were collected and analyzed using univariate and multivariable statistical models. Among our 85 identified patients, in-hospital mortality was significantly associated with positive cultures obtained from deep respiratory samples (OR=16.6, p=0.017) and diagnosis based on EORTC+PCR criteria (OR=12.4, p=0.016). Principal-component analysis revealed a homogeneous group of patients with positive deep respiratory swabs, haemopathy, ICU admission and a greater death ratio. We completed with an expert analyses on diagnosis, which revealed diagnostic variability with an overall Krippendorffs alpha about 0.32. Mucormycosis remains a challenging condition due to its rarity, severity, and diagnostic limitations. Incorporating PCR into diagnostic criteria and implementing early and tailored management for at-risk patients may improve clinical outcomes. Prospective studies are required to validate these findings and refine management strategies for this life-threatening infection.