Comparison of biofilm formation in clinical isolates of Candida species in a tertiary care center, North India.

Background and Objectives: Biofilms are colonies of microbial cells encased in a self-produced organic polymeric matrix. The biofilm production is more important for nonalbicans Candida (NAC); as C. albicans possess many other mechanisms to establish infections. Correct identification of Candida species has gained importance due to persistent rise in infections caused by NAC. We sought to isolate, identify Candida species in clinical isolates and study biofilm formation. Materials and Methods: Modified microtiter plate method was performed to study biofilm formation by isolates in Sabouraud's dextrose broth. It was then quantitatively assessed using a spectrophotometer. Biofilm formation was graded as negative, +1, +2, +3 and + 4 on the basis of percentage absorbance. Results: Biofilm formation was observed in 16 of 40 (40.0%) isolates of C. albicans as compared to 39 of 78 (50.0%) of isolates of NAC. Strong (+4) biofilm production was seen in maximum biofilm producers in C. tropicalis (12 of 27) followed by C. albicans (8 of 16). Total biofilm producers were significantly more among high vaginal swab isolates 63.2% (12 of 19) and urine isolates 59.2% (29 of 49), when compared to blood isolates 34.2% (13 of 38) as well as other isolates 27.5% (11 of 40). Interpretation and Conclusions: NAC species are qualitatively and quantitatively superior biofilm producers than C. albicans . Biofilm production is the most important virulence factor of NAC species and compared to other lesions, it is more significantly associated with luminal infections.