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[The dynamics of the invasive growth of Candida albicans in the host's tissues]
Abstract:
Using experimental models of candidal vaginitis in leukopenic mice and of stomatitis in neonatal animals, who developed the minimal inflammatory response, the author has defined the rate of invasive growth of C. albicans in mucosal stratified epithelium. Pseudomycelium was found to invade the epithelium at an average rate of 2 microns per hour, penetrating the entire epithelial lining within 24-48 hrs. These data have been extrapolated to a clinical condition. On the basis of measurements of mucosal epithelium thickness (carried out with autopsy and biopsy material), presumable periods of the total epithelium penetration were calculated; such penetration results in vascular invasion, thus making possible a disseminated involvement. These periods ranged from 22 to 59 hrs for different mucous membranes. Our findings demonstrate the significance of cellular and tissue defense reactions, which, if suppressed, may induce the fungi, normally found on epithelial surface as saprophytes, invade the host tissues and cause deep (and in some cases disseminated) mycotic involvement within several days.
Insights
Candida albicans invades mucosal epithelium at 2 microns/hour. Suppressed immune defenses allow this fungus to penetrate tissues, leading to deep or disseminated infections within days.
Area of Science:
- Mycology
- Infectious Diseases
- Immunology
Background:
- Candida albicans is a commensal fungus.
- Opportunistic infections can arise when host defenses are compromised.
- Understanding fungal invasion dynamics is crucial for treating invasive candidiasis.
Purpose of the Study:
- To determine the invasion rate of Candida albicans in mucosal stratified epithelium.
- To extrapolate experimental findings to clinical scenarios of invasive candidiasis.
- To highlight the role of host immune defenses in preventing fungal dissemination.
Main Methods:
- Experimental models of candidal vaginitis in leukopenic mice.
- Experimental models of stomatitis in neonatal animals with minimal inflammatory response.
- Measurement of mucosal epithelium thickness using autopsy and biopsy materials.
Main Results:
- Pseudomycelium invaded the epithelium at an average rate of 2 microns per hour.
- Complete epithelial penetration occurred within 24-48 hours in experimental models.
- Calculated epithelial penetration times ranged from 22 to 59 hours for different human mucous membranes, potentially leading to vascular invasion.
Conclusions:
- Suppressed cellular and tissue defense reactions are critical for Candida albicans to invade host tissues.
- Normally saprophytic fungi can cause deep and disseminated mycoses when immune defenses are impaired.
- The rate of fungal invasion suggests a rapid progression from superficial colonization to systemic infection.