Resumo

Histoplasmosis is a systemic mycosis caused by the geophilic dimorphic fungus Histoplasma capsulatum var.capsulatum. This agent can cause severe infection with high mortality in humans and animals, especially in immunocompromised individuals with disseminated forms. H. capsulatum usually has been found in environmental samples enriched with avian and/or bat excreta in caves, caverns, chicken coops, hollow trees, etc. The purpose of this research was investigate the detection of H. capsulatum var.capsulatum in soil samples from an Amazonian cave by PCR and NESTED-PCR. We evaluated the PCR-based method for the detection of Histoplasma capsulatum developed by Bialek et al. We optimised the concentration DNA template and annealing temperature of this PCR reaction. Samples with different concentrations of H. capsulatum DNA (25, 0.5, 1×10−2, 2×10−4, 4×10−6 and 8×10−8 ng) were used for amplification in order to determine the detection limit of protocol.We analysed the samples by electrophoresis on a 1.5% agarose gel as described by Bialek et al. The analysis of 30 soil samples from the Maroagas Cave used in nested PCR assay, demonstrated the presence of H. capsulatum DNA in five soil samples. None reaction PCR reaction carried out with the primer HC1 and HC2 was positive, however, the same 5 soil samples were positive when it was carried out this assay with the primers HC3 and HC4. Thus, simple PCR method can be used to detect the pathogen in soil samples and even to support a previous diagnosis.The fact of the isolated occurrence of this fungus in a cave the municipality in question leads us to think of the possibility of H. capsulatum in other caves in the region, seeing that they exhibit the same bioclimatic conditions , favorable to the development of this pathogen.