Membrane fluidity and lipid composition of fluconazole resistant and susceptible strains of Candida albicans isolated from diabetic patients

Ten clinical isolates of Candida albicans, five strains belonging to each of fluconazole resistant and susceptible groups isolated from diabetic patients, were studied for the membrane fluidity and lipid composition. Compared to fluconazole susceptible strains, fluconazole resistant ones exhibited enhanced membrane fluidity as measured by fluorescence polarization technique. The increased membrane fluidity was reflected in the decreased p-values exhibited by the resistant strains. On the other hand, susceptible isolates contained higher amount of ergosterol, almost twice as compared to resistant isolates which might have contributed to their lower membrane fluidity. However, no significant alteration was observed in the phospholipid and fatty acid composition of these isolates. Labeling experiments with fluorescamine dye revealed that the percentage of the exposed aminophospholipid, phosphatidylethanolamine was highest in the resistant strains as compared to the susceptible strains, indicating a possible overexpression of CDR1 and CDR2 genes in resistant strains. The results presented here suggest that the changes in the ergosterol content and overexpression of ABC transporter genes CDR1 and CDR2 could contribute to fluconazole resistance in C. albicans isolated from diabetic patients.