Velocity of Candida albicans invasion into host tissues.

Using 2 experimental models (candidal vaginitis in leukopenic mice and oral candidosis in neonatal rats) characterized by minimal inflammatory response to the pathogen, the rate of invasive growth of Candida albicans in stratified epithelia of mucosal membranes was defined. The pseudomycelium was found to invade animal epithelia at an average rate of 2 microns per hour, penetrating the entire epithelial thickness during 24-48 h. These data have been extrapolated to clinical pathology. On the basis of experimental data and by measuring the epithelial thickness in some human mucous membranes, the presumable periods of total epithelial penetration were calculated which may lead to vascular invasion and create the danger of dissemination. For different human mucous membranes these periods ranged from 22 to 59 h. These data emphasize the importance of cellular and tissue defense mechanisms, the inhibition of which may allow the fungi normally found on epithelial surfaces as commensals to invade the host tissues and to cause deep and disseminated mycotic lesions within several days.