Estratégias para o conhecimento da coccidioidomicose : uma doença emergente no Nordeste brasileiro

• Ano de defesa: 2006
• Autor(a) principal: Cordeiro, Rossana de Aguiar
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Palavras-chave em Português: Coccidioidomicose; Antifúngicos; Fungos
• Link de acesso: http://www.repositorio.ufc.br/handle/riufc/865

Coccidiodomycosis is a systemic infection caused by the dimorphic fungi species Coccidioides immitis and C. posadasii. The disease affects both humans and animals, and is considered endemic in the semiarid areas of Ceará State (Northeast Brazil), where it is caused by C. posadasii. The aims of this study were to analyse the phenotypical characteristics of C. posadasii and to develop culture independent methods for improving of the laboratorial diagnosis of coccidioidomycosis. The phenotypical study was conducted with 10 strains (7 from clinical and 3 from ambiental sources) by macro and micromorphology analyses; in vitro growth under different conditions of salinity, temperature and pH; nutritional analysis and antimicrobial susceptibility tests. In addition, methods of antigens extraction and amplification of C. posadasii DNA directly in sputum were also tested. The mycological analysis showed three morphological variations of C. posadasii strains cultivated in potato agar, Sabouraud agar and YEG agar. Regarding to micromorphology, it was observed that arthroconidia counts were related to colony aging and texture. Growth rates of C. posadasii strains were inhibited by high salt concentrations, temperatures above 40° C, but were not affected by the range of pH. Nutritional analyses showed that several compounds, including the oxidized ions, nitrite and nitrate, were efficiently metabolized by C. posadasii strains as carbon and/ or nitrogen sources. The antifungal susceptibility analysis showed that all of the strains of C. posadasii were sensitive to amphotericin B, caspofungin and the azoles ketoconazole, itraconazole, fluconazole, and voriconazole. With the exception of pyrazinamide, all of the tested drugs interfered with the in vitro growth of C. posadasii. Combined antituberculosis drugs also inhibit fungal growth in vitro. Experimental protocols produced a stable and immunoreactive antigen, suitable in presumptive serologic tests for the diagnosis of coccidioidomycosis. Molecular identification of C. posadasii was achieved by PCR amplification of the specific pra gene directly from filamentous cultures and sputum with fungal parasitic structures. The data obtained by phenotypical analyses may be useful in future studies for biological distinction of C. immitis and C. posadasii species. The results of this study provided approaches for a better understanding of coccidioidomycosis in Brazil