Isolamento e identificação de leveduras do gênero Candida em pacientes com câncer orogástrico: susceptibilidade a drogas antifúngicas, virulência e perfil de resposta imune

• Ano de defesa: 2014
• Autor(a) principal: Lourimar Viana do Nascimento Franco de Sousa
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Candida spp; Resposta imune; Leveduras; Diagnóstico; Antifúngicos; Câncer orogástrico; Identificação; Microbiologia; Neoplasias bucais; Candida; Leveduras (Fungos)
• Link de acesso: http://hdl.handle.net/1843/BUBD-ABZH78

Cancer is a chronic degenerative disease that presents a disordered growth of cells and may spread to other body regions. The process of carcinogenesis and oncogenesis ranges from early changes in DNA to tumor formation, which may cause the destruction of the host organism, slowly and progressively. As in other malignant neoplasms, oral cancer has its development stimulated by the interaction of environmental factors, carcinogens or carcinogens and host factors as age, race, sex and genetic inheritance. Some external agents are also predisposing to cancer development factors such as exposure to solar radiation, as well as smoking and chronic alcoholism. Opportunistic infections of the oral cavity are primarily caused by fungi of the genus Candida and occur frequently in this group of patients. Considering the aspects related to the presence of fungi in the oral cavity and its questionable role in cancer, the aim of this study was to determine the potential aggressor of Candida species among different patients who had orogastric cancer, including issues related to the diagnosis of neoplasia buccal, antifungal therapy and cell population involved in the immune response of the patient. To confirm the diagnosis of cancer, tissue fragments were subjected to cytological and histological analyzes. Both histopathologic as cytopathologic tests, considered a form of alternative diagnosis, showed sensitivity of 100% for all samples analyzed. In this study 59 patients with clinical diagnosis for cancer and presence of Candida spp. and 34 control subjects without cancer were included. Oral swabs samples of individuals were seeded in Sabouraud Dextrose Agar for identification of species. Yeasts, after screening with pigment production in the middle of CRHOMagarCandida were identified by morphological tests through microcultive and confirmatory testing by MALDI-TOF. Fifty (85%) of patients with cancer oro-gastric and 20 (59%) of the control subjects showed yeast in the oral cavity. Candida albicans was the most prevalent species, both in patients with cancer (48.4%) and in control subjects (66.7%). Among the 50 cancer patients who had yeast in the oral cavity, in eight of these, two different Candida species and in two, three different strains were isolated, totaling 62 samples. Of the 20 control subjects, positive for Candida in the oral cavity, one had two species, totaling 21 isolates. In the group with cancer 32 (51.6%) samples were identified as Candida albicans, 4 (6.5%) as C. tropicalis, 9 (14.5%) as C. glabrata, 4 (6.5%) as C. krusei, 8 (12.9%) as C. parapsilosis and 5 (8%) as C. lusitaniae. In the control group 14 yeast (66.7%) were identified as C. albicans, 5 (23.8%) as C. parapsilosis, 1 (4.8%) as C. krusei and 1 (4.8%) as C. glabrata. Yeasts were also assessed for the expression of virulence factors such as the production of proteinase and phospholipase, their adhesion ability, and as to the susceptibility to antifungal agents, commonly used in medical clinical profile. Among the samples of Candida spp. isolated, 54.2% and 32.5% produced phospholipase and proteinase, respectively. Isolates from patients with cancer showed higher proteinase production (41.9%) than those isolated from the control group (4.8%). Samples of Candida isolated from the oral cavity of patients with cancer had higher adhesion to buccal epithelial cells (BEC) than those of the oral cavity of people without alteration of the oral mucosa (p = 0.05). Candida species from cases with cancer showed higher sensitivity to isoconazole, voriconazole, ketoconazole and amphotericin B antifungals while the samples of Candida tropicalis were resistant to fluconazole. The samples of the control group demonstrated the sensitivity to all the antifungals tested. In this study 100% of individuals who had oral cancer were smokers and chronic alcoholics. An assessment was also performed, to be given the profile of immune response in the serum of individuals with oro-gastric cancer and the control group. In cancer patients there was a statistically significant increase in IL-2, IL-10, TNF, IFN- and IL-17 in the control group suggesting that there was a systemic change in these inflammatory cytokines in patients with neoplasia.