Nicotiana benthamiana as a model for studying Cryptococcus-plant interaction.

Cryptococcus gattii, an environmental yeast isolated from plants, is one of the agents of cryptococcosis. Here, we aimed to develop a plant model to study C. gattii-plant interaction, since it is unclear how it affects the plant and the yeast. We tested three inoculation methods (scarification, infiltration, and abrasion) in three plant species: Arabidopsis thaliana, Nicotiana tabacum, and N. benthamiana. Cryptococcus gattii was able to grow in all three models, with a peak of yeast cell burden after 7 days, without any pathological effects. Furthermore, the fungal burden was reduced later, confirming that C. gattii is not a phytopathogen. Cryptococcus gattii proliferation was higher in N. benthamiana, which presented an increase in the hydrogen peroxide content, antioxidant system activity, and indoleacetic acid (IAA) production. Cryptococcus gattii colonies recovered from N. benthamiana presented lower ergosterol content, reduced capsule, and increased growth rate in vitro and inside macrophages. In vitro, IAA altered C. gattii morphology and susceptibility to antifungal drugs. We hypothesize that C. gattii can temporarily colonize plant living tissues, which can be a potential reservoir of yeast virulence, with further dissemination to the environment, birds, and mammals. In conclusion, N. benthamiana is suitable for studying C. gattii-plant interaction.

Squamous cell carcinoma derived from chronic chromoblastomycosis in Brazil.

BACKGROUND: Chromoblastomycosis (CBM) is a chronic fungal infection caused mainly by the melanized fungi Fonsecaea species. The chronic lesions may be predisposed to develop into cancer, the most serious complication of the disease. METHODS: In this report, 7 cases of squamous cell carcinoma (SCC) resulting from chronic CBM in patients from Maranhão in the Brazilian Amazon are described. RESULTS: The 7 patients presented with SCC that resulted from chronic CBM, caused by Fonsecaea species >10 years' duration. The malignant lesions occurred independent of the antifungal therapy and all patients underwent curative amputation, except for 1 patient who developed metastases in the inguinal and intra-abdominal lymph nodes and thigh muscles. A majority of previous reports have focused on the malignant transformation of CBM described in only 1 patient each. This is a first report describing a group of patients from a single Brazilian state. CONCLUSIONS: Here, we provide new epidemiologic data on malignant CBM lesions, an endemic disease that is seemingly neglected worldwide. We reinforce the idea that typically chronic lesions may be predisposed to turn malignant.