What You Need to Know
Detections of Cladophialophora bantiana, a neurotropic mold with a 60% to 70% case-fatality rate, increased 4-fold at a University of Washington reference laboratory from 2023 to 2025, rising to 8 cases in 2024 and 14 in 2025 from samples submitted by 22 US jurisdictions.
The cause of the increase, the environmental reservoirs, and the risk factors remain unknown, and the infection can strike immunocompetent patients with no identified exposure, so investigators are calling for national surveillance and systematic case reporting.
Clinicians should consider C bantiana in any patient with a brain abscess and should treat promptly with combination antifungal therapy, such as liposomal amphotericin B, posaconazole or voriconazole, and flucytosine for at least 2 weeks, along with surgical excision when possible.
The reasons for the increase in cases are unknown, as are the environmental reservoirs, the epidemiology, and the risk factors for contracting the fungal disease. It is presumed that infection can occur by inhalation or direct inoculation after cutaneous injury. Nelson and colleagues report that 12% of the cases were detected in pulmonary samples, supporting the presumption of a respiratory route of infection.
The progress of the infection is primarily by hematogeneous spread to the brain. The infection can occur in immunocompetent persons, and typically presents without extracranial disease or an identified source or site of inoculation.There have also been, however, rare cases of pulmonary and cutaneous infections.
The investigators explain that C bantiana has only rarely been isolated from environmental sources, and that many patients do not appear to have similar exposure histories or risk factors. As there is no system of surveillance in place, and the nature of reference laboratory testing limits obtaining demographic data, they gathered context from case reports and retrospective literature reviews.This, they note, limits their elucidation of epidemiologic characteristics and patterns.
The limited demographic, occupational and clinical data and the unknown causes of the recent increase highlight, they indicate, "the need for more systematic reporting mechanisms for this mold and for clinical laboratories to publish numbers of detected cases."
In considering their advice to clinicians, Nelson and colleagues cite a 2024 study with 23 patients in France in which surgical excision or drainage of brain abscesses was associated with improved outcomes.2
"Thus, when possible, surgical excision should be considered, concurrently with administration of combination antifungal therapy," they recommend. "Although the most effective antifungal regimen is not known, triple therapy (treatment with lipsosomal amphotericin B, posaconazole or voriconazole, and flucytosine) for at least 2 weeks has demonstrated some effectiveness."
References
1. Nelson MT, Truong TT, Bourassa LA, et al. Notes from the field: Molecular detections of Cladophialophora bantiana at a clinical reference laboratory—United States, 2009-2026. MMWR Morb Mortal Wkly Rep. ePub: 2 October 2026. DOI: https://www.cdc.gov/mmwr/volumes/75/wr/mm7540e1.
2. Lortholary O, Garcia-Hermoso D, Sturny-Leclère A, et al. Reappraising Cladophialophora bantiana phaeohyphomycosis in France: Retrospective nation-based study. Lancet Microbe 2024; 5:100907. https://doi.org/10.1016/S2666-5247(24)00139-3.
