Abstract

Candida biofilms have become an increasingly significant clinical problem for hospital-acquired and device-associated infections due to their increased levels of resistance to the antifungals and disinfectants. This study examines the biofilm formation of fiveCandida isolates (Candida albicans, Candida glabrata, Candida parapsilosis, Candida krusei and Candida tropicalis), using the XTT (2, 3-Bis [2-methoxy- 4-nitro-5-(sulfenylamino) carbonyl-2H-tetrazolium-hydroxide]), and compares the susceptibility of biofilm cells to five disinfectants (glutaraldehyde, hydrogen peroxide, peracetic acid, ortho-phtalaldehyde and sodium hypochlorite) at the different times of biofilm formation (6th, 12th, 24th and 48th). Thus, the aim of our study was to investigate whether these disinfectants can interfere on Candida biofilm development phases. Our results indicated that the many variations in biofilm formation in clinical Candida species following disinfectant stress, however, none of the disinfectants completely removed the biofilm. Also, our transmission electron microscopic findings suggest that the disinfectants showed an important effect on the planktonic Candida cell. All these results also emphasize the importance of regular disinfection, before the starting of biofilm formation. On the other hand, XTT assay may not be the only adequate method to evaluate the efficacy of disinfectants. For these reasons, further studies are necessary to evaluate the disinfectant effectiveness on Candida biofilms.

Key words: Biofilm, Candida, tetrazolium salt (XTT), disinfectant, , transmission electron microscope (TEM).