Isolation of aParacoccidioides brasiliensisstrain from the soil of a coffee plantation in Ibiá, State of Minas Gerais, Brazil

Abstract

Paracoccidioides brasiliensis has rarely been isolated from its habitat in rural areas. In order to investigate the hypothesis that human infection with this fungus is linked to coffee plantations (Coffea arabica), material was collected monthly over a period of 1 year from farms in the town of Ibiá, State of Minas Gerais, Brazil. A total of 760 samples of soil, coffee leaves and fruits was cultured and inoculated into mice. A fungus isolated from the liver of a mouse inoculated with soil showed temperature-dependent dimorphism and in vitro mycelium and yeast phases characteristic of P. brasiliensis. Yeast cells of this fungus caused disseminated infection after intraperitoneal inoculation in Wistar rats from which the fungus was re-isolated. An antigen reacting with sera from patients with paracoccidioidomycosis was obtained from this P. brasiliensis strain; antigenic identity with strain 339 and with four other P. brasiliensis strains was detected by gel immunodiffusion. However, when the exo-antigen was submitted to SDS-PAGE, we observed low gp43 expression in this new strain, which we called Ibiá. The isolation of P. brasiliensis from the soil at a coffee plantation suggests that this is one of its habitats and supports the hypothesis of acquisition of paracoccidioidomycosis during agricultural activity in these areas.