Four Cases of Fusariosis in Hematologic Patients and Effective Environmental Control Measures

Fusariosis is an emerging and often fatal fungal infection in immunosuppressed patients, especially in onco-hematology. In this population, the disease is disseminated, with fever, metastatic skin lesions, and pneumonia. Skin lesions present as painful nodules, ulcers with irregular borders, and areas of central necrosis. Fusarium spp. are found in soil, plants, and contaminated materials; in hospital environments, the main sources are air-conditioning systems, water, and drains. Retrospective descriptive study of four patients diagnosed with fusariosis between July 2023 and July 2024, all with acute myeloid leukemia (AML) and/or bone marrow transplant (BMT), including clinical diagnosis, microbiological identification, and outcome. Environmental control measures that were effective in preventing new cases are also described. All patients had AML, three were haploidentical BMT recipients. All had skin lesions; one patient had onychomycosis on admission with recent AML diagnosis. Only three had Fusarium solani isolated in blood culture; one had diagnosis by histopathology of the lesion. Patients had poor oncologic prognosis, previous hospitalizations before BMT, prolonged aplasia, and all died, although only two had active infection at the time of death. Cases: 1. AML; 2 and 3. relapsed AML FLT3-positive; and 4. newly diagnosed FLT3-positive AML. Improvement measures: (1) Air-conditioning system: duct cleaning, change of HEPA filter replacement from annually to every six months, and monthly qualitative fungal air cultures. (2) Water: blocking access to hospital tap water, providing bottled mineral water for hand hygiene, brushing, and bathing; increasing chlorine concentration to a target of 2 ppm; cleaning and disinfection of water tanks and artesian wells; and implementing water treatment by reverse osmosis. PALL filters were installed in sinks and showers. We currently perform Fusarium cultures in water. No Fusarium spp. were isolated in air or water during or after the implementation of control measures, and no further cases occurred in the hospital. Fusariosis remains a significant challenge in clinical detection, microbiologic diagnosis, and outcomes in this population. Environmental analysis for Fusarium is difficult, and early risk identification is rare.