Development of a quantitative PCR detecting Cunninghamella bertholletiae to help in diagnosing this rare and aggressive mucormycosis

Mucormycosis is an invasive mold infection, frequently fatal in immunocompromised patients. We report the case of a patient with chronic lymphocytic leukemia admitted to the hematology unit for febrile aplasia. Pulmonary lesions suggesting a fungal infection expanded/increased despite a combination of posaconazole and liposomal amphotericin B. The fungal biomarkers performed repeatedly were negative. At D65 after chemotherapy a bronchial biopsy was positive for Cunninghamella bertholletiae. The patient died despite appropriate antifungal management. A qPCR targeting Cunninghamella was developed a posteriori, and a retrospective analysis showed that a sample was positive more than 30 days before culture-based identification could be made.