Geotrichosis Due to Magnusiomyces capitatus: A Severe Emerging Invasive Fungal Disease

Geotrichosis is a rare opportunistic mycosis caused by emerging yeasts rarely associated with fungemia. We report a case of invasive Magnusiomyces capitatus (M. capitatus) infection in a neutropenic patient. A 71-year-old man with rectosigmoid cancer undergoing chemotherapy was admitted to the emergency department with septic shock. Laboratory tests revealed a severe inflammatory response, agranulocytosis, and acute renal failure requiring hemodialysis via a femoral catheter. An infectious workup performed at the Central Parasitology and Mycology Laboratory of Ibn Sina University Hospital in Rabat included blood cultures, urine samples, hemodialysis catheter samples, and a protected distal specimen (PDS). Empirical broad-spectrum antibiotic therapy was initiated, followed by caspofungin due to a lack of clinical improvement. Microscopic examination of urine, catheter, and PDS specimens revealed arthrospores. Blood cultures turned positive after 20 hours of incubation. Cultures on Sabouraud agar showed whitish, dry colonies with irregular edges, typical of Geotrichum spp. Precise identification of M. capitatus was achieved using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF). Despite appropriate antifungal treatment, the patient died 10 days after admission. This case underlines the severity of invasive M. capitatus infections, often overlooked in immunocompromised patients, and highlights the critical importance of rapid and accurate diagnosis with modern tools like mass spectrometry to optimize management.