Biofilm formation and virulence properties of Candida spp. isolated from hospitalised patients in Tunisia

Abstract

Control of opportunistic yeast is one of the factors reducing nosocomial infection in hospital. In this study, we investigated the presence of virulence factors including antifungal susceptibility, haemolytic potency, proteinase and phospholipase production. In addition biofilm formation was assessed using the XTT assay. A total of 24 Candida strains were isolated and identified. The most common species were Candida albicans and Candida glabrata (40.7%), followed by Candida dubliniensis (8.3%), Candida kefyr (4.2%) and Candida krusei (4.2%). In addition, 62.5% of strains were resistant to itraconazole and 16.7% of strains were resistant to fluconazole. All the strains were susceptible to amphotericin B. Phospholipase activity showed that 8.3% of the total strains were very strong producers and 41.7% were strong producers. Furthermore, three strains (12.5%) were found to have very strong proteinase activity. All the tested strains revealed beta haemolytic potency. All Candida strains were adhesive to polystyrene 96-well microtitre plates to differing degrees. The OD values of XTT reduction at 492 nm ranged from 0.025 (ca12) to 0.927 (ca2). The majority of C. albicans strains were highly metabolically active in comparison with the other species. Control of fungal infections in hospitalised patients is important to prevent the emergence of multi-resistant strains to commonly used antifungal agents. © Springer-Verlag and the University of Milan 2010.