ORAL CANDIDA - CLEARANCE, COLONIZATION, OR CANDIDIASIS

Candida albicans is frequently isolated from the human mouth, yet few carriers develop clinical signs of candidiasis. Oral candidiasis prese nts clinically in many forms. This reflects the ability of the yeast t o colonize different oral surfaces and the variety of factors which pr edispose the host to Candida colonization and subsequent infection. Co lonization of the oral cavity appears to be facilitated by several spe cific adherence interactions between C. albicans and oral surfaces whi ch enable the yeast to resist host clearance mechanisms. Thus, Candida has been shown to adhere to complement receptors, various extracellul ar matrix proteins, and specific sugar residues displayed on host or b acterial surfaces in the oral cavity. Oral candidiasis results from ye ast overgrowth and penetration of the oral tissues when the host's phy sical and immunological defenses have been undermined. Tissue invasion may be assisted by secreted hydrolytic enzymes, hyphal formation, and contact sensing. While these and other phenotypic characteristics may endow certain Candida species or strains with a competitive advantage in the oral cavity, it is the host's immune competence that ultimatel y determines whether clearance, colonization, or candidiasis occurs.