Study On Post-Antifungal Effect (PAFE) of certain antifungal agents on Candida species and its impact on fungal virulence factors

Abstract

The study was conducted to determine the Post-antifungal effect (PAFE) induced by polyenes and azoles singly and/or combined, against clinical isolates of Candida species. The study was also focused on investigating the impact of PAFE on the candida! virulence factors, including germ tube formation (GTF), cell surface hydrophobicity (CSH), and adherence. A total of 95 clinical Candida isolates were collected from different clinical specimens. They were identified as C. albicans (61); C. tropicalis (16); C. glabrata (15); and C. Krusei (3). The antifungal sensitivity pattern of the tested isolates was determined by the disc diffusion method on RPMI-1640 medium, while the antifungal's minimum inhibitory concentrations (MICs) were determined using the agar dilution method. Four isolates of Candida species, sensitive to all of the tested antifungals, were exposed for a period of 1 h to three concentrations (4, 1, and 114 x MIC) of each of the tested antifungals. Following removal of the antifungal agents by I o•3 dilution, the PAFEs were determined

spectrophotometrically. The duration of the PAFEs of nystatin, fluconazole, ketoconazole, miconazole, and the combined (nystatin-ketoconazole) ranged from: (0.3-3 h), (0.3-1.2 h), (-1.4 -1 h), (0.3 -7.7 h), (0.7- 8 h) respectively, depending on the concentration and the species tested. When the antifungal's inhibitory effect on GTF of C. albicans during the PAFE period was investigated, it was found that, almost total suppression of germ tube formation of C. albicans isolate was observed following 1 h exposure to 1 x MIC of nystatin, and the combined nystatin - ketoconazole, with a mean percentage reduction of 73.41 and 87.23%

respectively.