Genetic diversity and exoenzyme activities of Candida albicans and Candida dubliniensis isolated from the oral cavity of Brazilian periodontal patients.

OBJECTIVE: Mucosal surfaces are the primary oral reservoirs of Candida species, but these species can also be found in subgingival biofilm. The present study investigated the genetic diversity and production of exoenzymes of C. albicans and C. dubliniensis isolated from the oral cavity of systemically healthy patients with periodontitis. DESIGN: Fifty-three patients were analysed. Samples were collected from three oral cavity sites (periodontal pocket, gingival sulci and oral mucosa), plated and, after isolation, suspect strains of C. albicans and C. dubliniensis were identified by PCR. The genetic diversity of the isolates was evaluated by RAPD and the activities of the secreted aspartyl proteinases and phospholipases were evaluated by the agar plate method. RESULTS: Twenty-one patients showed positive results for Candida spp. There were no statistically significant differences between genders, or between sites. C. albicans was the most frequently found specie, while C. dubliniensis was isolated from the periodontal pocket of only one patient. Sixteen genotypes were detected among the C. albicans isolates, and one among the C. dubliniensis isolates. The similarity coefficient (S(SM)) values among the C. albicans genotypes ranged from 0.684 to 1.0 with an average of 0.905+/-0.074. All isolates produced high levels of Saps and most of them produced high levels of phospholipases. No relationship was found between the genotypes and the pattern of enzymatic production. There was no association between specific genotypes and their site of isolation. CONCLUSIONS: The results of the present study suggest that genetically homogeneous strains of C. albicans are present in the oral cavity of patients with periodontitis and that these strains are capable of producing high levels of exoenzyme.

Increase in probing depth is correlated with a higher number of Prevotella intermedia genotypes.

BACKGROUND: The aims of this study were to determine the genotypic diversity of Prevotella intermedia in subgingival plaque samples by using two techniques, arbitrarily primed polymerase chain reaction (AP-PCR) and heteroduplex analysis, and to assess the relationship of this diversity with increase in probing depth. METHODS: The subgingival plaque samples were obtained from 12 patients using paper points inserted into periodontal pockets (diseased sites) and healthy gingival sulci (healthy sites) of the same subjects. After isolation and identification, AP-PCR was performed for genotypic characterization of P. intermedia (80 isolates). The clinical samples with a positive result for P. intermedia were amplified by 16S rRNA-based PCR method, and the amplicons were subjected to heteroduplex analysis. RESULTS: The agreement between the two methods was very high; the AP-PCR and heteroduplex analysis showed that subjects harbored between one and five distinct genotypes of P. intermedia, with a positive association between numbers of genotypes by AP-PCR (P = 0.0042) or heteroduplex (P = 0.0099) and increase in probing depth. No matching of P. intermedia genotypes was observed between healthy and diseased sites of the same individual. Interindividual analyses demonstrated absence of identical clones and indicated a high level of genetic diversity in the species. CONCLUSION: A clear relationship was observed between a higher number of genotypes and increase in probing depth; these results suggest that environmental challenges in the periodontal pockets may modulate the microbiota by selecting genotypes best able to exploit the environment.