Candida glabrata : a review of its features and resistance

Candida species belong to the normal microbiota of the oral cavity and gastrointestinal and vaginal tracts, and are responsible for several clinical manifestations, from mucocutaneous overgrowth to bloodstream infections. Once believed to be non-pathogenic, Candida glabrata was rapidly blamable for many human diseases. Year after year, these pathological circumstances are more recurrent and problematic to treat, especially when patients reveal any level of immunosuppression. These difficulties arise from the capacity of C. glabrata to form biofilms and also from its high resistance to traditional antifungal therapies. Thus, this review intends to present an excerpt of the biology, epidemiology, and pathology of C. glabrata, and detail an approach to its resistance mechanisms based on studies carried out up to the present.The authors are grateful to strategic project PTDC/SAU-MIC/119069/2010 for the financial support to the research center and for Celia F. Rodrigues' grant

Genetic and phenotypic evaluation of Candida albicans strains isolated from subgingival biofilm of diabetic patients with chronic periodontitis

Candida spp. are commensal microorganisms that are part of the microflora of different sites within the oral cavity. In healthy subjects, who have an unaltered immunological status, these yeasts do not cause disease. However, in immunosuppressed individuals whose condition may have been caused by diabetes mellitus, Candida spp. can express different virulence factors and may consequently become pathogenic. Studies have detected the presence of Candida spp. in periodontal sites of patients with chronic periodontitis, especially those that are immunologically compromised. However, the role of these microorganisms in the pathogenesis of periodontal disease is still unknown. The objectives of this study were: (1) to isolate and identify Candida albicans strains from subgingival sites of diabetic patients with chronic periodontitis; (2) to evaluate the following virulence factors; colony morphology, proteinase, phospholipase and hemolysin activities and cell surface hydrophobicity (CSH) under different atmospheric conditions; and (3) to determine the genetic patterns of these C. albicans isolates. Microbial samples were collected from subgingival sites and seeded on CHROMagar for subsequent identification of C. albicans by polymerase chain reaction (PCR). For the phenotypic tests, all strains of C. albicans were grown under reduced oxygen (RO) and anaerobiosis (ANA) conditions. Genotypes were defined by the identification through PCR of the transposable introns in the 25S rDNA. The results obtained relative to virulence factors were analyzed according to the atmospheric condition or genetic group, using Chi-square and Wilcoxon non-parametric tests. In this study, 128 strains were identified as C. albicans and of these, 51.6% were genotype B, 48.4% were genotype A and Genotype C was not found. Most of the strains were alpha-hemolytic in both atmospheric conditions, without a statistical difference. However, when comparing the genotypes, 46.1% of the genotype A strains were beta-hemolytic. In relation to colony morphology, 100% of the strains under ANA showed rough colonies, which were especially prevalent in genotype A isolates. In contrast, most of the colonies were smooth under RO. C. albicans strains did not produce proteinase and phospholipase activity in the total absence of oxygen. In RO, most strains had high proteinase activity and were positive by phospholipase tests (P < 0.05). Hydrophobicity was higher in anaerobiosis and was noted mainly for genotype A isolates. In conclusion, environmental oxygen concentration influenced the virulence factors of C. albicans strains isolated from subgingival sites of diabetic and periodontal patients. In addition, genotype A seems to be more virulent based on the phenotypic tests evaluated in this study.50546747

Periodontal conditions and prevalence of putative periodontopathogens and Candida spp. in insulin-dependent type 2 diabetic and non-diabetic patients with chronic periodontitis-A pilot study

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Objectives: The aims of this study were to evaluate periodontal conditions and identify the presence of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Tannerella forsythia, and four different species of Candida (C. albicans, C. dubliniensis, C. glabrata and C. tropicalis) in periodontal pockets and furcation sites of insulin-dependent type 2 diabetic and non-diabetic patients with generalised chronic periodontitis. Design: Clinical parameters, including oral status assessed using plaque index, gingival index, probing depth, gingival recession and clinical attachment level and systemic conditions with fasting glucose level or glycosylated haemoglobin were measured in diabetic and non-diabetic patients with chronic periodontitis. Samples of subgingival biofilm were obtained from the periodontal pockets and furcation sites and submitted to phenol-chloroform DNA extraction and PCR analysis using specific primers. Results: Clinical conditions of diabetic and non-diabetic patients were similar, without statistical differences in both periodontal indexes and glucose levels (p > 0.05). Diabetics had a higher prevalence of Candida spp., mainly C. albicans and C. dubliniensis, and a lower frequency of T. forsythia, when compared to non-diabetic patients, for both periodontal sites. C. glabrata and C. tropicalis were not found in periodontal pockets and furcation sites of non-diabetic patients. Conclusion: The results demonstrated a strong colonisation of Candida spp. in the periodontal sites of diabetic patients that have generalised chronic periodontitis with a higher prevalence of C. dubliniensis followed by C. albicans. (C) 2011 Elsevier Ltd. All rights reserved.561010981105Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Adhesion and invasion of Candida albicans from periodontal pockets of patients with chronic periodontitis and diabetes to gingival human fibroblasts

The objectives of this study were to evaluate clinical isolates of Candida albicans, particularly their adhesion to and invasion of gingival human fibroblasts in culture and to measure nitric oxide concentration (NO) produced by fibroblasts in the presence of these yeasts. Sixteen strains of C. albicans isolated from patients with chronic periodontitis and diabetes mellitus type II were divided on the basis of phenotypic tests into two groups, i.e., highly or weakly hydrophobic. Primary cultures of human fibroblasts were isolated from gingival biopsies and after subsequent subcultures, the cells were seeded into culture plates and incubated for 24 h. C. albicans strains were inoculated into these plates and maintained for 2 and 4 h to assess their adhesion and invasion, respectively. The number of adherent or invasive yeasts was evaluated by assessing colony-forming units (CFU). The production of NO by fibroblasts was also quantified. The results showed that strains with high hydrophobicity had a greater ability to adhere and invade fibroblasts (p < 0.05, ANOVA and Tukey). The production of NO was higher for the most hydrophobic strains, but did not reach statistical difference with the weakly hydrophobic isolates. These data indicated that the hydrophobicity may play a role in the adhesion and invasion of C. albicans in fibroblast cultures.501434

Biodegradation and Abrasive Wear of Nano Restorative Materials

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)The purpose of this study was to evaluate the biomechanical degradation of two nanofilled restorative materials (a resin-modified glass ionomer, Ketac N100 and a composite, Filtek Z350), compared with conventional materials (Vitremer and TPH Spectrum). Twenty specimens obtained from each material were divided into two storage groups (n=10): relative humidity (control) and Streptococcus mutans biofilm (biodegradation). After 7 days of storage, roughness values (Ra) and micrographs by scanning electron microscopy (SEM) were obtained. In a second experimental phase, the specimens previously subjected to biodegradation were fixed to the tooth-brushing device and abraded via toothbrushes, using dentifrice slurry (mechanical degradation). Next, these specimens were washed, dried, and reassessed by roughness and SEM. The data were submitted to repeated measures three-way analysis of variance (ANOVA) and Tukey tests (p<0.05). There was statistically significant interaction among factors: material, storage (humidity/biofilm), and abrasion (before/after). After biodegradation (S mutans biofilm storage), Ketac N100 presented the highest Ra values. Concerning bio plus mechanical challenge, TPH Spectrum, Ketac N100, and Vitremer presented the undesirable roughening of their surfaces, while the nano composite Filtek Z350 exhibited the best resistance to cumulative challenges proposed. The degraded aspect after biodegradation and the exposure of fillers after mechanical degradation were visualized in micrographs. This study demonstrated that the nanotechnology incorporated in restorative materials, as in composite resin and resin-modified glass ionomer, was important for the superior resistance to biomechanical degradation.366670677Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES