Knowledge and attitudes about HIV/AIDS of dental students from Kuwait and Sri Lanka

Several studies regarding knowledge and attitudes of dental students towards HIV/AIDS have been reported from various countries. However, to the best of our knowledge, an international comparison between countries with diverse cultural and educational backgrounds has not been reported in the literature. The aim of this study was to compare the knowledge and attitudes towards HIV/AIDS of dental students of Kuwait University (KU), Kuwait and the University of Peradeniya (UP), Sri Lanka, the only dental schools in the respective countries. A cross-sectional survey was conducted among a total of 258 dental students, representing the clinical years of both universities, using a similar structured questionnaire with sixty questions to examine their knowledge of various aspects of HIV/AIDS and thirteen questions to examine their attitudes towards the disease. The mean knowledge and attitude scores were calculated and compared between students from the two universities using t-test with SPSS 17.0. A total of 215 questionnaires were completed and returned, giving a total response rate of 83.3 percent. The KU students were significantly more knowledgeable (p=0.018) regarding HIV/AIDS than the UP students. However, the UP students demonstrated a more highly significant positive attitude (p<0.001) towards the disease than those in KU. This information might help to define strategies to improve the quality of education in these countries.     

The in vitro post-antifungal effect of nystatin on Candida species of oral origin

The post-antifungal effect (PAFE) is defined as the suppression of growth that persists following limited exposure of yeasts to antimycotics and subsequent removal of the drug. Although limited data are available on the PAFE of nystatin on oral isolates of C albicans, there is no information on non-albicans Candida species. As nystatin is the commonest antifungal agent prescribed in dentistry, the main aim of this investigation was to measure the PAFE of oral isolates of Candida belonging to six different species (five isolates each of C. albicans, C. tropicalis, C. krusei, C. parapsilosis, C. glabrata and C. guilliermondii) following limited exposure (1 h) to nystatin. The yeasts were examined for the presence of the PAFE after 1 h exposure to the minimum inhibitory concentration (MIC) of nystatin. The PAFE was determined as the difference in time (h) required for the growth of the drug-free control and the drug-exposed test cultures to increase to the 0.05 absorbance level following removal of the antifungal agent. The mean duration of nystatin-elicited PAFE was lowest for C. albicans (6.85 h) and greatest for C. parapsilosis (15.17 h), while C. krusei (11.58 h), C. tropicalis (12.73 h), C. glabrata (8.51 h), and C. guilliermondii (8.68 h) elicited intermediate values. These findings clarify another intriguing possibility for the persistent, chronic recurrence of oral C. albicans infections despite apparently adequate antifungal drug regimens. The significant variations in nystatin-induced PAFE amongst non-albicans species may also have clinical implications, in terms of nystatin regimens used in the management of these fungal infections.     

Inhalational and topical steroids, and oral candidosis: a mini review

Candidosis is by far the commonest oral fungal infection in man and could manifest as an adverse effect of drug therapy such as inhaled or topically applied corticosteroids. Due to the anti-inflammatory and immunosuppressive effect steroids are used in the management of bronchial asthma and oral mucosal diseases. In this mini review we discuss the clinical and laboratory findings on the relationship between steroid inhalers, other topical steroids and oral candidosis, possible mechanisms of pathogenicity following such therapy as well as the precautions that could be taken to minimize this adverse side effect.     

Adhesion of oral Candida species to human buccal epithelial cells following brief exposure to nystatin

Opportunistic oral infections caused by Candida albicans and non-albicans Candida species are particularly common in compromised patients. Nystatin, which belongs to the polyene group of antimycotics, is frequently used as a topical agent in the treatment of oro-pharyngeal candidosis. It is recognized that due to the delivery mode of nystatin (i.e. topical, intermittent), as well as the cleansing effect of saliva within the oral environment, the yeasts undergo a relatively brief exposure to this drug during treatment. Nevertheless, there is a sparsity of data on the effect of such brief exposure to nystatin on the pathogenic attributes of Candida such as their adherence to host surfaces. The adhesion of microbes to host mucosal surfaces is a major determinant of successful colonization and infection. Thus the main aim of our investigation was to compare the in vitro adhesion of 30 oral isolates of Candida belonging to six different species (comprising Candida albicans, Candida tropicalis, Candida glabrata, Candida guilliermondii, Candida krusei and Candida parapsilosis) to human buccal epithelial cells, following their brief exposure (1 h) to minimum inhibitory concentration of nystatin, and subsequent removal of the drug. The adhesion of these isolates to buccal epithelial cells was assessed by a previously described adhesion assay. Compared with the controls, there was a significant reduction in buccal epithelial cell adhesion of all six Candida species after drug exposure (54%-68%). However the adhesion of C. albicans isolates was the least affected by nystatin exposure, which was significantly different from that of the non-albicans species. These findings imply that sub-therapeutic levels of nystatin, which are likely to persist in the oral cavity during dosing intervals, may also be beneficial, as they inhibit candidal colonization. The significant difference in nystatin-induced suppression of adhesion between C. albicans and the non-albicans species investigated is a further testimonial for the pre-eminent virulence of the former species.     

Impact of Brief and Sequential Exposure to Nystatin on the Germ Tube Formation and Cell Surface Hydrophobicity of Oral Candida Albicans Isolates from Human Immunodeficiency Virus-Infected Patients

Objective

To evaluate the impact of brief and sequential exposure to nystatin on the germ tube formation and cell surface hydrophobicity of oral isolates of Candida albicans obtained from patients infected with human immunodeficiency virus (HIV).

Materials and Methods

After determining the minimum inhibitory concentration of nystatin, 10 oral isolates of C. albicans from 10 different HIV-infected patients were briefly (1 h) and sequentially (10 days) exposed to subtherapeutic concentrations of nystatin. Following a subsequent drug removal, the germ tube formation and cell surface hydrophobicity of these isolates were determined via a germ tube induction assay and an aqueous hydrocarbon assay, respectively. The data obtained from these assays for the control (unexposed to nystatin) and nystatin-exposed isolates were analyzed using Student''s t tests.

Results

The mean percentage reduction in the germ tube formation and cell surface hydrophobicity of the nystatin-exposed isolates compared to the controls was 30.12 ± 1.99 (p < 0.001) and 29.65 ± 2.33 (p < 0.001), respectively.

Conclusion

These data elucidate the possible pharmacodynamic mechanisms by which nystatin might operate in vivo in the modulation of candidal virulence.Key Words: Candida albicans, Cell surface hydrophobicity, Germ tubes, Nystatin