Aim:  The major objective of the study was to analyse exopolysaccharide produced by a biofilm forming‐clinical strain of Candida albicans. Methods and Results:  The biofilm‐forming ability of C. albicans recovered from infected intrauterine devices (IUDs) was evaluated using XTT (2,3‐bis[2‐methoxy‐4‐nitro‐5‐sulfophenyl]‐2H‐tetrazolium‐5‐carboxanilide) reduction assay. The morphological characteristics of the biofilm were assessed using scanning electron microscopy (SEM), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Biochemical characterization of the exopolysaccharide was carried out by gel permeation chromatography, gas chromatography (GC), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Microscopic studies of C. albicans biofilm revealed complex, heterogeneous three‐dimensional structure, in which yeast cells and hyphal elements were entrenched within exopolysaccharides matrix. Chromatographic analysis data indicated C. albicans exopolysaccharide (c. 300 kDa) to be made up of four major sugar units. The FTIR spectrum revealed specific absorbance of O–H, C–H, O=C=O, C=O, C–N and C–C ring stretching. 1H and 13C NMR data showed the presence of β (1→6) and β (1→3) linkages in the exopolysaccharide chain that were assigned to α‐d‐glucose and β‐d‐glucose, α‐d‐mannose, α‐l‐rhamnose and N‐acetyl glucosamine (β‐d‐GlcNAc), respectively. Conclusions:  Study suggested the production of a water soluble c. 300 kDa exopolysaccharide by C. albicans made up of glucose, mannose, rhamnose and N‐acetyl glucosamine subunits. Significance and Impact of the Study:  The study could assist in the development of novel therapeutics aimed at disrupting C. albicans biofilms that will translate into improved clearance of Candida‐related infections.

The inhibitory effect of 30 plant oils was evaluated against biofilm forming Candida albicans strain (CA I) isolated from clinical samples, which was sensitive to 4 microg/ml of fluconazole, used as a positive control. The standard strain (MTCC 227, CA II) used in this study was found to be highly resistant to fluconazole, 3,000 microg/ml of which was required to inhibit the growth of this strain partially, and complete inhibition could not be achieved. Eighteen among the 30 plant oils tested were found to show anti-Candida activity by disc diffusion assay. Effective plant oils were assessed using XTT (2, 3-bis [2-Methoxy-4-nitro-5-sulphophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay for biofilm quantification. Four oils eucalyptus, peppermint, ginger grass and clove showed 80.87%, 74.16%, 40.46% and 28.57% biofilm reduction respectively. Minimum inhibitory concentration (MIC) values were calculated using agar dilution assay. Scanning electron microscopic (SEM) analysis further revealed reduction in C. albicans biofilm in response to effective oils. The substantial antifungal activity shown by these plant oils suggests their potential against infections caused by C. albicans.

The significant antifungal activity of these oils suggests that they could serve as a source of compounds with therapeutic potential against Candida-related infections.

Our survey revealed that infected intrauterine devices (IUDs) recovered from patients suffering from reproductive tract infections (RTIs) were tainted with Candida biofi lm composed of a single or multiple species. Scanning electron microscopy (SEM) analysis of C. albicans biofi lm topography showed that it consists of a dense network of mono-or multilayer of cells embedded within the matrix of extracellular polymeric substances (EPS). Confocal scanning laser microscopy (CSLM) and atomic force microscopy (AFM) images depicted that C. albicans biofi lms have a highly heterogeneous architecture composed of cellular and noncellular elements with EPS distributed in the cell-surface periphery or at cell-cell interface. Biochemical analysis showed that EPS produced by C. albicans biofi lm contained signifi cantly reduced total carbohydrate (40%), protein (5%) and enhanced amount of hexosamine (4%) in contrast to its planktonic counterparts. The in vitro activity of antifungal agents amphotericin B, nystatin, fl uconazole and chlorhexidine against pre-formed C. albicans biofi lm, assessed using XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay revealed increased resistance of these infectious biofi lm (50% reduction in metabolic activity at a concentration of 8, 16, 64, 128 μg/ml respectively) in comparison to its planktonic form.

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