Fonsecaea species cause chromoblastomycosis and phaeohyphomycosis, but links between environmental exposure and infection are poorly defined. We describe a 4-year-old boy with finger swelling after oak tree laceration in Houston, Texas. Broad-range polymerase chain reaction identified F. pedrosoi or F. monophora, and metagenomic sequencing of tree bark and soil detected Fonsecaea DNA.

[This corrects the article DOI: 10.3389/fimmu.2026.1843553.].

Chromoblastomycosis, caused primarily by Fonsecaea pedrosoi, is traditionally associated with traumatic environmental inoculation. We analyzed 50 Rhipicephalus sanguineus/R. microplus ticks from chromoblastomycosis-endemic Venezuelan states (Lara and Portuguesa) using Oxford Nanopore amplicon sequencing. Remarkably, F. pedrosoi dominated the tick eukaryotic microbiome, comprising 78% and 75% of fungal communities in Lara and Portuguesa, respectively. This unexpected high abundance across geographically distinct endemic foci suggests a previously unrecognized ecological association between ticks and the pathogen. While environmental transmission remains established, these findings provide first molecular evidence of F. pedrosoi in tick microbiomes, warranting investigation into potential carrier, vector or reservoir roles that may reshape chromoblastomycosis epidemiology understanding.

Chromoblastomycosis is a chronic neglected tropical mycosis caused predominantly by the melanized fungus Fonsecaea pedrosoi. Current treatments are prolonged and frequently ineffective, highlighting the need for new therapeutic strategies. Here, we applied an integrated immunoproteomic and reverse vaccinology approach to identify immunogenic antigens from F. pedrosoi and evaluate their vaccine potential. Fungal proteins were separated by two-dimensional electrophoresis and immunoreactive proteins were detected using sera from infected mice. Mass spectrometry identified several antigenic proteins, including enolase and previously uncharacterized hypothetical proteins. Computational epitope prediction revealed a peptide candidate (Hp11696; LGFMSAFKASKLIAI) with high predicted affinity for MHC class II molecules. Functional assays demonstrated that Hp11696 stimulated antigen-specific CD4[+] T-cell proliferation in splenocytes derived from infected animals. Immunization with Hp11696 significantly reduced fungal burden in a murine model of chromoblastomycosis and induced cytokine responses characterized by increased IFN-γ and IL-10 production. Collectively, these findings demonstrate that immunoproteomics-guided antigen discovery can identify protective peptide epitopes from fungal pathogens. The Hp11696 peptide represents a promising candidate for the development of peptide-based vaccines targeting chromoblastomycosis.

Fonsecaea monophora is a dematiaceous fungus with worldwide distribution that can cause chromoblastomycosis, an implantation mycosis and a neglected tropical disease. F. monophora also causes phaeohyphomycosis, including central nervous system infections like brain abscesses, with high mortality rates. In the absence of clinical breakpoints, epidemiological cutoff values (ECVs) can aid clinicians in monitoring antifungal resistance trends and guide initial antifungal selection. To establish F. monophora MIC distribution and ECVs, we performed antifungal susceptibility testing (AFST) on F. monophora isolates. AFST data on F. monophora isolates were collected at 14 laboratories during September 2023-May 2026. Species identification was previously confirmed by DNA sequence analysis. AFST was performed by CLSI M38 standard broth microdilution method for itraconazole, voriconazole, posaconazole, isavuconazole, ketoconazole, terbinafine, flucytosine, and amphotericin B. The ECVs were established using the iterative statistical method with ECOFFinder (v2.1) following CLSI M57 guidelines. We analyzed MIC results from 137 F. monophora isolates. The calculated ECVs were itraconazole, 2 μg/mL; voriconazole, 0.25 μg/mL; posaconazole, 1 μg/mL; isavuconazole, 0.25 μg/mL; and terbinafine, 0.5 μg/mL. Amphotericin B and flucytosine had bimodal distributions, and no ECVs were set. Ketoconazole did not have data from ≥100 isolates. These F. monophora ECVs can detect non-wild-type isolates to reevaluate antifungal treatment and investigate treatment failure associated with potential clinical resistance. Established through a global multicenter collaboration, these values provide a baseline to better understand the in vitro antifungal susceptibility profile of this species and monitor resistance.IMPORTANCEFonsecaea monophora is a dematiaceous fungus with worldwide distribution that can cause chromoblastomycosis, an implantation mycosis and neglected tropical disease of the skin and subcutaneous tissue. F. monophora also causes phaeohyphomycosis, including central nervous system infections like brain abscesses with high mortality rates. The paucity of antifungal susceptibility testing data on F. monophora complicates interpretation of minimum inhibitory concentration (MIC) values. We performed antifungal susceptibility testing on 137 F. monophora isolates to establish MIC distributions and epidemiological cutoff values (ECVs) for eight antifungals, including those commonly used to treat F. monophora infections. The calculated ECVs for commonly used antifungals were 2 μg/mL for itraconazole, 0.25 μg/mL for voriconazole, 1 μg/mL for posaconazole, and 0.5 μg/mL for terbinafine. ECVs can assist in selecting potential treatments for F. monophora and tracking antifungal resistance trends.

Fonsecaea pedrosoi, a pathogenic fungus within the order Chaetomycosis of the family Dematiaceae, is the primary causative agent of Chromoblastomycosis (CBM). Its clinical manifestations are diverse and lack specificity, often being confused with other skin diseases, which can easily lead to misdiagnosis or missed diagnosis. This article reports a case of a 36-year-old immunocompromised female with chronic infection caused by F. pedrosoi following minor trauma to the right knee. The patient presented with plaque-like hyperplasia, pruritus, desquamation, and suppuration of the local skin over the right knee, with persistent and refractory clinical course. The definite diagnosis was ultimately established through mycological, histopathological, and molecular biological examinations, followed by appropriate therapeutic intervention. This case indicates that chromoblastomycosis is prone to missed or delayed diagnosis due to its atypical clinical manifestations. Moreover, immunocompromised patients are more likely to experience prolonged disease course and slow recovery, highlighting the critical importance of accurate diagnosis and rational selection of treatment regimens. Combined with a literature review, it analyzes the clinical characteristics and key points in diagnosis and treatment of the disease, explores approaches to strengthen the awareness of clinical monitoring, and aims to improve the overall public health awareness of the disease.

Zearalenone (ZEN) is a secondary metabolite produced by Fusarium species that threatens food safety and animal health. In this study, we identified and isolated a novel ZEN-degrading enzyme FeZ12 from Fonsecaea erecta through sequence homology alignment, systematic learning models (SoluProt, DeepSoluE), and molecular dynamics (MD) simulations. FeZ12 was successfully heterologously expressed in Escherichia coli and exhibited optimal activity at 37 °C and pH 7.0. To enhance enzyme activity and thermal stability, multiple FeZ12 mutants were constructed based on structure-guided and mutation prediction analyses. Single mutants G179R, P127V, and T9V exhibited 2.8-fold, 2.5-fold, and 2.2-fold higher activities than the wild type, respectively. The triple mutant T9V/P127V/G179R exhibited a 3.2-fold activity increase and markedly improved thermal stability, retaining 65% of its activity after incubation at 45 °C for 30 min. MD simulations revealed that mutations stabilized the FeZ12 structure and optimized the catalytic geometry. This work provides a practical engineering route and a thermostable enzyme candidate for ZEN detoxification in food and feed systems, with potential for industrial application.

Chromoblastomycosis (CBM) is a chronic, neglected tropical fungal infection. Its immunopathogenesis, particularly the mechanism underlying its chronicity, remains poorly understood.