Gram stain to the rescue: a case report of cerebral phaeohyphomycosis by Cladophialophora bantiana in an immunocompetent 24-year-old

Cerebral phaeohyphomycosis due to Cladophialophora bantiana: case report and systematic review of cases

PURPOSE

Cladophialophora bantiana is a wonted melanized fungus causing brain abscess. In past many cases were reported from Asia, particularly from India. Of late, there is a rise in cases in places besides Asia and hence a review of the cases is warranted.

METHODS

We present a case of fatal cerebral phaeohyphomycosis caused by C. bantiana and conduct a systematic review of culture confirmed brain abscess due to C. bantiana reported between 2015 and 2022.

RESULTS

Of the 39 cases found, majority (68%) were immunocompromised. The various clinical presentations were headache (53%), hemiparesis (34%), visual disturbance (25%), altered sensorium (18%), aphasia/dysarthria (12%) and seizures (9%). Isolated lesion was observed in 18 (60%) patients. In the sequence of occurrence, the lesions were in frontal (30%), temporal (27%) and parietal (20%) region. There were five cases with coinfections such as concurrent detection of Nocardia pneumonia in two cases, toxoplasma DNA in brain abscess, coexisting pulmonary Cryptococcus neoformans infection and coexisting Candida in a case of brain abscess in one case each. Surgical intervention was performed in 84% cases. Antifungal therapy included voriconazole (80%), liposomal amphotericin B (76%), 5-fluorocytosine (30%), posaconazole (10%), and amphotericin B deoxycholate (6%). The overall mortality was 50% with lower mortality (42%) in regions outside Asia compared to Asia (63.6%) though not statistically significant.

CONCLUSIONS

C. bantiana brain abscess is an emerging infection worldwide. Next generation sequencing is an upcoming promising diagnostic test. Early complete excision of the lesion with effective antifungals may improve the outcome.

[Fungal infection by Cladophialophora bantiana and development of cerebral phaeohyphomycosis. A systematic review of 58 case reports]

INTRODUCTION

INTRODUCTION

Cladophialophora bantiana is a filamentous fungus, known as a dematiaceous fungus because of the presence of melanin. This fungus is of clinical importance because it is neurotropic and causes cerebral phaeohyphomycosis.

MATERIAL AND METHODS

The available scientific information on the development of cerebral phaeohyphomycosis caused by Cladophialophora bantiana was analysed by selecting articles from the PubMed, Scopus and Google Scholar databases that describe case reports of fungal infection by C. bantiana in adults, taking into account the analysis of the patients' symptomatology, clinical history and neuroanatomical damage, in addition to considering the mortality of the condition.

RESULTS

India and United States were the countries with most case reports, with 32 and 11 cases respectively. Moreover, in terms of neuroanatomical lesions, the majority of patients suffered mixed lesions (29%) and frontal lobe lesions (22%). In accordance with the patients' condition, the pathology has a mortality rate of 62%.

CONCLUSIONS

It is concluded that cerebral phaeohyphomycosis has a high mortality rate, there is no standardised treatment and, in most cases, the fungal infection of the brain is mixed and affects several different parts of it. Furthermore, if not diagnosed and treated in time, it can lead to the patients' death.

Cladophialophora bantiana metabolites are efficient in the larvicidal and ovicidal control of Aedes aegypti, and Culex quinquefasciatus and have low toxicity in zebrafish embryo

Mosquitoes' current insecticide resistance status in available public health insecticides is a serious threat to mosquito control initiatives. Microbe-based control agents provide an alternative to conventional pesticides and insecticides, as they can be more targeted than synthetic insecticides. The present study was focused on identifying and investigating the mosquitocidal potential of Cladophialophora bantiana, an endophytic fungus isolated from Opuntia ficus-indica. The Cladophialophora species was identified through phylogenetic analysis of the rDNA sequence. The isolated fungus was first evaluated for its potential to produce metabolites against Aedes aegpti and Culex quinquefasciatus larvae in the 1-4th instar. The secondary metabolites of mycelium extract were assessed at various test doses (100, 200, 300, 400, and 500 μg/mL) in independent bioassays for each instar of selected mosquito larvae. After 48 h of exposure, A. aegypti expressed LC₅₀ values of 13.069, 18.085, 9.554, and 11.717 μg/mL and LC₉₀ = 25.702, 30.860, 17.275, and 19.601 μg/mL; followed by C. quinquefasciatus LC₅₀ = 14.467, 11.766, 5.934, and 7.589 μg/mL, and LC₉₀ = 29.529, 20.767, 11.192, and 13.296 μg/mL. The mean % of ovicidal bioassay was recorded 120 h after exposure. The hatchability (%) was proportional to mycelia metabolite concentration. The enzymatic level of acetylcholinesterase in fungal mycelial metabolite treated 4th instar larvae indicated a dose-dependent pattern. The GC-MS profile of C. bantiana extracts identified five of the most abundant compounds, namely cyclobutane, trans-3-undecene-1,5-diyne, 1-bromo-2-chloro, propane, 1,2,3-trichloro-2-methyl-, 5,5,10,10-tetrachlorotricyclo, and phenol, which had the killing effect in mosquitoes. Furthermore, the C. bantiana fungus ethyl acetate extracts had a strong larvicidal action on A. aegypti and C. quinquefasciatus. Finally, the toxicity test on zebrafish embryos revealed the induction of malformations only at concentrations above 1 mg/mL. Therefore, our study pioneered evidence that C. bantiana fungal metabolites effectively control A. aegypti and C. qunquefasciastus and show less lethality in zebrafish embryos at concentrations up to 500 μg/mL.

Human Dectin-1 deficiency impairs macrophage-mediated defense against phaeohyphomycosis

Subcutaneous phaeohyphomycosis typically affects immunocompetent individuals following traumatic inoculation. Severe or disseminated infection can occur in CARD9 deficiency or after transplantation, but the mechanisms protecting against phaeohyphomycosis remain unclear. We evaluated a patient with progressive, refractory Corynespora cassiicola phaeohyphomycosis and found that he carried biallelic deleterious mutations in CLEC7A encoding the CARD9-coupled, β-glucan-binding receptor, Dectin-1. The patient's PBMCs failed to produce TNF-α and IL-1β in response to β-glucan and/or C. cassiicola. To confirm the cellular and molecular requirements for immunity against C. cassiicola, we developed a mouse model of this infection. Mouse macrophages required Dectin-1 and CARD9 for IL-1β and TNF-α production, which enhanced fungal killing in an interdependent manner. Deficiency of either Dectin-1 or CARD9 was associated with more severe fungal disease, recapitulating the human observation. Because these data implicated impaired Dectin-1 responses in susceptibility to phaeohyphomycosis, we evaluated 17 additional unrelated patients with severe forms of the infection. We found that 12 out of 17 carried deleterious CLEC7A mutations associated with an altered Dectin-1 extracellular C-terminal domain and impaired Dectin-1-dependent cytokine production. Thus, we show that Dectin-1 and CARD9 promote protective TNF-α- and IL-1β-mediated macrophage defense against C. cassiicola. More broadly, we demonstrate that human Dectin-1 deficiency may contribute to susceptibility to severe phaeohyphomycosis by certain dematiaceous fungi.