Human dental biofilm: Screening, characterization, in vitro biofilm formation and antifungal resistance of Candida spp.

The importance of dental plaque biofilms for oral and dental disease was proposed recently. This study determined the presence of Candida spp. in dental plaques of both males and females. Pooled samples of dental plaque were collected from 25 males and 55 females aged between 25 and 50 years. Colony growth was verified and 30 Candida isolates were chosen for the screening. The identification of biofilm forming Candida was confirmed by performing several screening techniques (Microtiter plate method, Test tube method). Screened positive Candida isolates DV1, DV17 and DV21 were characterized by several biochemical tests including growth on Hi-Crome agar. Molecular characterization has also been performed for isolates DV1, DV17 and DV21 by sequencing 18S rRNA gene. Phylogenetic trees were constructed for three Candida isolates and identified as Candida albicans DV1, C. albicans DV17 and C. albicans DV21. The biofilm formation of Candida spp. on catheter was evaluated using scanning electron microscopic analysis. The extra cellular polysaccharide (EPS) quantity was measured with the effect of different carbon sources, adherence time and biofilm forming time. The above isolates were screened for antifungal resistance against six clinically important antifungal agents such as Amphotericin B, Ketaconazole, Fluconazole, Itraconazole, Nystatin and Clotrimazole (10 μg/ml). The biofilm forming isolates were significantly resistant to the antifungal drugs in comparison with non-biofilm forming Candida isolates. The present study reveals the presence of Candida biofilm on human dental surface and indicates the magnitude of antibiotic resistance.