The Susceptibility of Candida albicans to Gamma-Radiations and Ketoco-nazole Depends on Transitional Filamentation
Simone Cagnacci*, 1, Rachele Grasso2, Anna Marchese1, Renzo Corvò2, Eugenio Debbia1, Lorenzo Rossi1
1 Institute of Microbiology “C.A Romanzi”, Department DISCAT, University of Genoa, Largo Rosanna Benzi, 10, 16132, Genoa, Italy
2 Department of Radiotherapy, National Cancer Institute of Genoa and University of Genoa, Largo Rosanna Benzi, 10, 16132, Genoa, Italy
The virulence of C. albicans is associated with the transitional evolution from yeast to filamentous forms. We were interested in the effects amphotericin B (AMB), ketoconazole (KTC) and γ-radiations might have on these broadly defined phenotypes as determined by the CFU procedure. By using collagen gel as the 3-dimensional support of cell culture, diverse experimental conditions were contemplated in order to modulate the differentiation of Candida during sessile and planktonic growth. These conditions included the co-culture with human epithelial and endothelial cells and treatment with farnesol, tyrosol and conditioned medium from P. aeruginosa. The overall results were as follows: 1) The survival of Candida was inhibited by the exposure to γ-radiations, but only after the organism was induced to progress into excess filamentation, while in normal growth conditions it proved to be radioresistant; 2) AMB inhibited the growth of yeast forms, while KTC was specifically toxic to filamentous forms and 3) the combined treatment of filamentous Candida with KTC and γ-radiations resulted in the synergistic inhibition of the organism. These findings indicate that both the radiosensitivity of C. albicans and its response to the synergistic effects of γ-radiations and KTC are filamentation-dependent pharmacological processes.
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* Address correspondence to this author at the Institute of Microbiology “C.A Romanzi”, Department DISCAT, University of Genoa, Largo Rosanna Benzi, 10, 16132, Genoa, Italy; Tel: +39-010-353-7655; Fax: +39-010-353-7651; E-mail: firstname.lastname@example.org