Aspergillus flavus culture filtrate inhibits candidal biofilm development in-vitro

Abstract

Background: Invasive candidiasis, a major health concern in developing countries, has an attributable mortality of 15-40%. It is associated with biofilm formation over indwelling devices. Our study was aimed at finding low-cost alternatives to inhibit this biofilm development in-vitro. Methods: One loopful of Aspergillus flavus clinical isolates were cultured in YPD(Yeast Extract-Peptone-Dextrose) broth for 1 week. Culture filtrate was prepared by filtering it through membrane filter of pore size 0.45 μm. Candia albicans and C. tropicalis clinical isolates were cultured in YPD broth at 37 °C for 48 hours. Dilutions of yeast cell suspensions were prepared in YPD broth as well as Aspergillus culture filtrate, and yeast cell density was adjusted to 106 cells/ml in both cases. Then 100 μl of each was poured in wells of a flat-bottomed microtitre plate. The plate was incubated at 37 °C and washed at intervals of 90 minutes, 24 hours and 48 hours with sterile Phosphate Buffered Saline (pH 7.2). Each time after washing, wells were reloaded with respective cell suspensions. Then the optical density(O.D.) was measured in a spectrophotometer at 450 nm wavelength after staining the wells with 1% Safranine in 95% ethanol. The plate was also observed under Inverted microscope to see biofilm development. Tests were done in triplicate. Results: Aspergillus filtrate significantly reduced the biofilm formation in C. albicans and C. tropicalis , as observed microscopically and spectrophotometrically. Mean O.D.value of Candida spp. in YPD broth was 0.795 0.6 and that of filtrate containing Candida spp. suspension was 0.576 ± 0.1(p value: <0.05). Conclusion: Culture filtrate of Aspergillus flavus disrupts Candidal biofilm development in-vitro.