Serotype distribution and secretory acid proteinase activity of Candida albicans isolated from the oral mucosa of patients with denture stomatitis

Denture stomatitis is the most common form of oral Candida infection in humans. In the current study, the distribution of Candida albicans serotype A and B as well as the activity of the secreted acid proteinase were determined in clinical isolates from patients with denture stomatitis. It was found that 70% of individuals with clinical signs of denture stomatitis exhibited fungal growth, with C. albicans representing the most frequently isolated species (75%). Of the C. albicans isolates, 75% were serotype A and 25% were serotype B, representing a significant increase of serotype B compared to a control group of non-denture-wearing HIV-seronegative individuals with oral candidiasis, but no significant difference compared with isolates from HIV-seropositive patients, who also exhibited a high percentage of serotype B. The mean secretory acid proteinase activity of C. albicans isolates from denture stomatitis patients (2796 +/- 819 U/l) was statistically not different from the mean secretory acid proteinase activity in non-denture-wearing HIV-seronegative individuals (2324 +/- 1487 U/l). Both values were significantly lower than the mean secretory acid proteinase activity of C. albicans from HIV-seropositive individuals (4256 +/- 2372 U/l). No correlation exists between the C. albicans serotype and the amount of secreted acid proteinase, indicating that serotype and secretory acid proteinase expression are two independent pathogenetic factors in oral candidiasis. These results indicate that there seems to be strain selection for C. albicans serotype B in denture stomatitis. These results further indicate that increased secretion of the acid proteinase seems to be of pathogenetic significance in the candidiasis of HIV-seropositive patients but not in denture stomatitis. Nevertheless, the secretory acid proteinase is likely to be an important pathogenetic factor also in denture stomatitis, where an increased secretion of the acid proteinase may not be required because of decreased salivary flow and a low pH under the denture, which will result in a high enzymatic activity.

Effect of different surface textures on retentive strength of tapered posts

STATEMENT OF PROBLEM

Tapered posts allow for the preservation of tooth substance in the fragile apical area and are advantageous in clinical situations where they conform to the root and canal configuration of endodontically treated teeth. However, their lower retention compared with passive parallel-sided or active threaded posts is a disadvantage.

PURPOSE

This study determined the retentive strength of tapered titanium posts with different surface textures and examined the effect of roughening dentinal walls of the prepared post space.

MATERIAL AND METHODS

Posts with four surface configurations (smooth, with and without grooves, and sandblasted, with and without grooves) were examined when cemented in extracted anterior teeth.

RESULTS

The smooth post showed the lowest retentive strength. Sandblasting the smooth post more than doubled its retentive strength. The retentive strength of both smooth and sandblasted posts could be further increased by the addition of circumferential grooves. Roughening the dentinal walls of the prepared post space increased the retentive strength of sandblasted posts with and without grooves even more.

CONCLUSIONS

These findings indicated that, when a tapered post is used, roughening the dentin canal wall, as well as sandblasting and grooving the post, can provide statistically significant additional resistance to dislodgment.

Increased expression of Candida albicans secretory proteinase, a putative virulence factor, in isolates from human immunodeficiency virus-positive patients

The increased prevalence and the severity of oropharyngeal candidiasis in human immunodeficiency virus (HIV)-positive patients are attributed exclusively to the virus-induced immune deficiency of the host. The present study was aimed at answering the question of whether Candida albicans secretory proteinase, a putative virulence factor of the opportunistic C. albicans yeast, has any potential influence on the clinical manifestation of oropharyngeal candidiasis in HIV-positive patients. We measured the secretory proteinase activities of clinical C. albicans isolates from the oropharynges of either HIV-positive individuals (n = 100) or a control group (n = 122). The mean secretory proteinase activity of C. albicans isolates from the HIV-positive group (4,255 +/- 2,372 U/liter) was significantly higher compared with that of isolates from the control group (2,324 +/- 1,487 U/liter) (P < 0.05). The higher level of secretory proteinase activity in the culture supernatants of individual C. albicans isolates correlated with the increased level of proteinase expression on the cell surface, as revealed by cytofluorometry, and with higher levels of secretion of the immunodetectable protein, as shown by Western blotting (immunoblotting). Proteinase activity within the population of C. albicans isolates from HIV-positive individuals was independent of the patient's clinical disease stage and the CD4+/CD8+ cell numbers. Furthermore, no correlation of the proteinase activities with the C. albicans serotype was found, although C. albicans serotype B was significantly more frequent in the HIV-positive group (40%) compared with that in the control group (12%). However, a positive correlation of proteinase activity to antifungal susceptibility was evident. The C. albicans isolates from the HIV-positive group that were characterized by higher levels of proteinase activity were also less susceptible to the widely used azole antifungal ketoconazole and fluconazole. Collectively, the present data are consistent with a concept of early preferential selection of a subpopulation of C. albicans in HIV-infected patients.