Oral candida carriage and the antifungal activity of parotid secretion
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https://hdl.handle.net/2144/35613Abstract
When local or general predisposing factors are present, Candida, an oral
opportunistic pathogen, may cause acute or chronic oral infections. It is well known that
healthy individuals differ with respect to the carrier status of Candida a/bicans. The aim
of this project was to determine Candida carriage among healthy individuals, and to
investigate the spectrum of antifungal activity of parotid secretion. To determine the
oral Candida carrier status, masticatory stimulated whole saliva (WS) was collected
from thirteen healthy subjects, every 2 to 3 days, during a 2 week time interval. The cell
sediment from 1 ml WS was suspended in 100 μI phosphate buffered saline (PBS, pH
7.0) and plated on Sabouraud dextrose agar or on Chromagar to determine the
number and type of fungi present in WS, respectively. Gustatory stimulated parotid
secretions (PS) were collected from four of the thirteen subjects, two being low and two
being high Candida carriers. The fungistatic activity of the collected PS secretions was
evaluated in growth media assaying 15 medically important fungi including 6 strains of
C. albicans. Four of the 13 subjects were found to be non-Candida carriers in WS (zero
colonies on all sampling occasions), five were low carriers (zero to a few colonies
cultured per occasion) and four were high carriers (never zero colonies, mostly double
digit counts). The total number of C. albicans in the carriers showed considerable
fluctuation, which was established to be due to the sampling occasion. However, noncarriers maintained their non-carrier status during the entire interval of examination. PS collected from four of the thirteen subjects exhibited a surprising trend of being
fungistatic toward many fungal species, as evidenced from the low IC50 values, while
being 20-50 fold less active against the six evaluated strains of C. albicans. This was
true for PS samples collected from low or high Candida carriers. Considering the fact
that PS is a major contributor to oral fluid, this observation would suggest a lower overall antifungal activity in the oral cavity toward C. albicans in particular. It is
hypothesized that this may be a contributing factor to the successful oral colonization
of C. albicans.
Description
Thesis (MSD)--Boston University, Goldman School of Dental Medicine, 2008 (Dept. of Periodontology and Oral Biology). Includes bibliographical references: leaves 46-50.
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