Susceptibility of Candida spp. Oral isolates for azolic antifungals and amphotericin B

Aims: Among the oral infections, candidosis may be considered the most frequent, and C. albicans the most prevalent species. Meanwhile, the non-albicans species may also be related to other infections processes and be able to affect the oral cavity, including periodontal disease. In this sense, understanding the relationship between Candida spp. and host, it is necessary and justified the search of mechanisms modulators of infections and treatments against diseases associated with these yeasts. Methods: Nineteen patients with periodontal disease were involved in this study. The aim was evaluate the susceptibility to azoles antifungals fluconozole, itraconazole, ketoconazole and the polienic anfotericin B against Candida spp isolated from three different sites of the oral cavity from these patients (periodontal disease, being periodontal pocket, oral mucosa and ridge gingival), by the minimum inhibitory concentration method – MIC. Results: Among the samples of C. albicans, 88% showed susceptibility depending on the concentration (SCD) and 3.6 % were resistant to at least one antifungal azole studied. Among the others species, 57% presented SDC and 42.8% showed resistance to at least one of the antifungal azole tested. Regarding to Anfotericin B, 90% of the C. albicans isolates and 3% of the nonalbicans showed resistance. There was no occurrence of resistance to the fluconazole and only 3.6% of C. albicans and 40% of the non-albicans were SDC to this antifungal. Conclusions: Patients with periondontal disease showed relevant levels of colonization by Candida spp, mainly at the oral mucosa and periodontal pocket showing important occurrence of SDC and resistance to the antifungals drugs tested.

Biotyping and genotypic diversity among oral Candida albicans strains from caries-free and caries-active healthy children

Cepas orais de Candida albicans coletadas de crianças saudáveis cárie ativas e livres de cárie com idade variando de 24 a 36 meses, foram estudadas. O propósito do estudo foi determinar a atividade da proteinase e da fosfolipase produzida por Candida albicans nos dois grupos e comparar com a diversidade genotípica usando o método AP-PCR. As cepas identificadas como C. albicans por testes morfológicos e de fermentação, foram cultivadas em meio ágar proteinase e fosfolipase a 37ºC por 7 e 4 dias, respectivamente. Após o período de incubação, a atividade enzimática das cepas proteinase e fosfolipase positiva foram medidas. Todas as cepas foram submetidas a técnica genotípica AP-PCR, usando o primer arbitrário AP-3. A análise enzimática demonstrou que não há diferença entre os dois grupos estudados. O método AP-PCR foi eficiente em demonstrar o polimorfismo genético de C. albicans intra indivíduos demonstrando uma maior diversidade clonal em crianças cárie ativas em relação as livres de cárie. Dendogramas de similaridade demonstraram semelhança na linhagem clonal apenas intra-indivíduos. Os resultados sugerem que o perfil enzimático não depende das características genotípicas das cepas.

Candida albicans proteinases

Candida species are ubiquitous commensal yeast that usually reside as part of an individual´s normal mucosal microflora and can be detected in approximately 50% of the population in this form. However, if the balance of the normal flora is disrupted or the immune defences are compromised, Candida species can invade mucosal surfaces and cause disease manifestations. Determining exactly how this transformation from commensal to pathogen takes place and how it can be prevented is a continuing challenger for the medical mycology field. Attributes that contribute to Candida albicans virulence include adhesion, hyphal formation, phenotypic switching and extra cellular hydrolytic enzyme production. The extra cellular hydrolytic enzyme, especially the secreted aspartyl proteinases (Saps), are one a few gene products that have been shown to directly contribute to C. albicans pathogenicity. Given the limited number of suitable and effective antifungal drugs, the continuing increase in the incidence of Candida infections, together with increasing drug resistance, highlights the need to discover new and better agents that target fundamental biological processes and or pathogenic determinants of C. albicans.