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Updated: Aug 1, 2026

Bio-energetics Investigation of Candida albicans Using Real-time Extracellular Flux Analysis
Published on: March 19, 2019
Candida albicans--do mycelia matter?
Abstract:
Growth of Candida albicans in the mycelial phase is neither necessary for initiation of infection in the kidney of the mouse, following intravenous inoculation, nor for the establishment of chronic renal colonization. However, mycelial formation would appear to be important in the establishment of pelvic lesions with their associated pathological changes. Two mycelia-less mutants, CA-2 and MM2002, in the early stages of infection tended to develop in the glomeruli of the mouse kidney cortex while the wild-type parent strains spread throughout the cortex and medulla, with only occasional involvement of glomeruli. The mutants appeared to stimulate a milder inflammatory response than the parent strains. In chronic infections with wild-type strains, tangled masses of mycelia filled the renal pelvis, but pyelonephritis and hydronephrosis did not depend on a persistent cortical infestation. Yeasts of the mutant strains persisted in the body of the kidney and stimulated a continuing neutrophil response. Systemic infections with wild-type strains were eliminated by treatment with low doses of an azole antifungal drug, ICI 195,739, or with amphotericin B, whereas systemic infections with the mutant strains were much reduced, but not eliminated, by relatively high doses of either of the two drugs. Unlike azole drugs, amphotericin B does not show differential activity against the two morphological forms of C. albicans. Because kidney infections with the mutant strains are relatively resistant to amphotericin B as well as the azole tested, we conclude that the impressive activity of azoles in vivo may not be explained entirely by their inhibition of mycelial growth.
Insights
Mycelial growth of Candida albicans is not essential for kidney infection initiation or chronic colonization but aids in lesion development. Mycelia-less mutants showed altered kidney distribution and reduced antifungal drug susceptibility.
Area of Science:
- Medical Mycology
- Renal Pathogen Research
Background:
- Candida albicans exhibits dimorphism, switching between yeast and mycelial forms.
- The role of C. albicans mycelial growth in renal infection pathogenesis remains incompletely understood.
Purpose of the Study:
- To investigate the necessity of Candida albicans mycelial growth for kidney infection initiation, colonization, and lesion development.
- To compare the infectivity and antifungal susceptibility of wild-type C. albicans and its mycelia-less mutants in a murine kidney infection model.
Main Methods:
- Intravenous inoculation of mice with wild-type C. albicans and two mycelia-less mutants (CA-2, MM2002).
- Histopathological examination of kidneys to assess fungal distribution and inflammatory responses.
- Evaluation of pyelonephritis and hydronephrosis.
- Treatment of systemic infections with an azole antifungal (ICI 195,739) and amphotericin B to determine drug efficacy.
Main Results:
- Mycelial growth was not essential for initial infection or chronic colonization but contributed to pelvic lesion formation.
- Mycelia-less mutants localized primarily in glomeruli, unlike wild-type strains spreading throughout the cortex and medulla.
- Mutants induced a milder inflammatory response compared to wild-type strains.
- Chronic wild-type infections featured extensive mycelial masses in the renal pelvis.
- Mutant infections were significantly less responsive to both azole and amphotericin B treatments compared to wild-type infections.
Conclusions:
- Candida albicans mycelial development is crucial for pelvic lesion establishment but not for initial renal infection or chronic colonization.
- Mycelia-less C. albicans mutants exhibit distinct kidney infection patterns and reduced susceptibility to antifungal therapies.
- The in vivo efficacy of azole antifungals may involve mechanisms beyond the simple inhibition of mycelial growth.
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