Candidoses orales et prothèses dentaires

The prevalence of selected genes involved in biofilm formation in Candida albicans isolated from the oral cavity

Introduction. C. albicans genome sequencing enables investigation of the role of particular genes in biofilm formation involving the yeast-like fungi.

Aim. The aim of the study was to determine the genotypes of C. albicans isolates on the basis of the presence of the selected genes involved in biofilm formation.

Material and methods. The study material included C. albicans strains isolated from the oral cavity of 654 healthy individuals. The strain biofilm-forming capacity was estimated with the MTT assay and menadione. The presence of HWP1, ALS3, TUP1, NGR1, SAM2 and CYS3 genes was investigated.

Results. In total, 15 gene combinations were found, including nine gene combinations for strains with a confirmed biofilm-forming capacity, 11 – for the strains without this capacity, and five – independent of biofilm-forming capacity. A combination involving all the genes occurred in 72.5% of all biofilm-forming strains and in 53.8% of all strains that do not form biofilm. Moreover, the genetic material of 14.3% of all strains not involved in biofilm formation did not contain any of the studied genes. For one of the biofilm-species, no analyzed genes were found.

Conclusions

1. The absence of correlation between gene combinations HWP1, ALS3, TUP1, NGR1, SAM2 and CYS3 and biofilm-forming capacity of the studied C. albicans strains confirms the multigenetic – and not yet fully known – molecular basis of the formation of this structure. This result corresponds to the data reported by other researchers.

2. Knowledge on the genetic foundations of biofilm formation is still developing and the list of biofilm-related genes has been considerably extended.

3. The absence of correlation between the combinations of investigated genes and the biofilm-forming capacity of the studied C. albicans strains confirms a multigenetic, basis of this structure.

4. The research on genes activated or inhibited during biofilm formation is extremely important, because it would enable the development of effective methods to disturb the biofilm forming process at the molecular level. There is a need for such methods in our clinical practice to prevent biofilm formation in the oral cavity.

Microbial contamination of removable dental prosthesis at different interval of usage: An in vitro study

Background:

Loss of teeth affects the individual's health. Many factors determine the need to wear a removable dental prosthesis. Due to nature of design, age and lack of awareness, prosthesis often are neglected to maintain in an aseptic condition leading to microbial contamination. This provided an impetus for the present study with the aim of determining the microbial contamination of removable dental prosthesis.

Methodology:

Total, 45 patients wearing removable dental prosthesis were randomly selected. Patients were divided into three groups as per duration of usage since 1 month, 6 month and ≥1 year. Sterile cotton swab moistened with phosphate buffer saline (PBS) was used to collect swab from the fitting areas of prosthesis. Swab samples was inserted immediately into the sterile tube containing 1 ml of PBS solution, 10 μl PBS is inoculated on the blood agar and MacConkey agar plates using spread plate technique. Samples were cultured and incubated at 37°C for 48 h. Calibrated microbiologist isolated, identified and counted microorganisms using colony counter. Depending on the nature of data, statistical analysis was done applying Kruskal–Wallis test, Mann–Whitney U-test and Chi-square test.

Result:

Streptococcus species and Staphylococcus aureus were the common microorganisms isolated in all three groups and was statistically significant at P <0.05. Candida albicans, Diptheroid, Escherichia coli, Micrococcus species were isolated from Group II and Group III.

Conclusion:

There is a linear increase in microbial contamination of removable dental prosthesis as the duration of usage increases and might increase the susceptibility of individuals' to many diseases.

Candida albicans susceptibility to lactoperoxidase-generated hypoiodite

In vivo, lactoperoxidase produces hypothiocyanite (OSCN⁻) from thiocyanate (SCN⁻) in the presence of hydrogen peroxide (H₂O₂); in vitro, iodide (I⁻) can be oxidized into hypoiodite (OI⁻) by this enzyme. The aim of this study was to compare in vitro the anti-Candida effect of iodide versus thiocyanate used as lactoperoxidase substrate to prevent Candida biofilms development. Candida albicans ATCC 10231 susceptibility upon both peroxidase systems was tested in three different experimental designs: (i) in a liquid culture medium, (ii) in an interface model between solid culture medium and gel containing the enzymic systems, (iii) in a biofilm model onto titanium and acrylic resin. Yeast growth in liquid medium was monitored by turbidimetry at 600 nm. Material-adherent yeast biomass was evaluated by the tetrazolium salt MTT method. The iodide-peroxidase system has been shown to inhibit Candida biofilm formation at lower substrate concentrations (~200 fold less H₂O₂ donor) and for longer incubation periods than the thiocyanate-peroxidase system. In conclusion, efficiency of lactoperoxidase-generated OI⁻ to prevent C. albicans biofilm development allows refining iodine antifungal use in ex vivo conditions.