Magnusiomyces capitatus, an Unusual Cause of Invasive Fungal Infections in Neutropenic Patients: Case Reports and Outbreak Investigation.

Magnusiomyces capitatus is an environmental fungus found in soil, water, air, plants, and dairy products which may cause opportunistic infections in patients with haematological disorders resulting in high mortality rates. This series of the first reported cases in Ireland discusses investigation of two patients with underlying haematological disorders, hospitalised in the Irish National Adult Stem Cell Transplant Unit (NASCTU), who developed line-related fungaemias with M. capitatus within a three-month period. Patient A was a 49-year-old gentleman with a background of myelodysplastic syndrome with a large paroxysmal nocturnal haemoglobinuria clone who underwent an allogeneic stem cell transplant (ASCT). He developed a prolonged bloodstream infection with M. capitatus and was treated with antifungals but unfortunately passed away 30 days following first detection of M. capitatus from blood. Patient B is a 35-year-old lady with a background of aplastic anaemia who received an ASCT with blood cultures later growing M. capitatus. She developed a disseminated infection with skin involvement and brain lesions. She remains on long-term suppressive antifungals post discharge. Outbreaks of disseminated M. capitatus infection have been reported in several haematology units, related to contaminated medical devices and dairy products. In this situation, environmental and food sampling did not provide any evidence of M. capitatus, and whole genome sequencing proved that the isolates were unrelated. indicating no link between the two cases within a short period in the NASCTU. Increasing rates of rare invasive yeasts means that consideration should be given to management in vulnerable populations such as haematology patients post ASCT.