Analysis of Interactions Between Candida Albicans and Enterococcus Faecalis in an Iron Rich Environment

Abstract

Objective: Failed root canals have been associated with a variety of microorganisms, such as Entercoccus faecalis (E. faecalis) and Candida albicans (C. albicans). The goal of the present study is to better understand the interactions between E. faecalis and C. albicans. Specifically, the cellular morphology of these interactions and the effect on cell aggregation and biofilm formation. Since much of C. albicans’ adhesion mechanisms are regulated by high iron levels, this study also seeks to analyze the role of iron in the interactions between C. albicans and E. faecalis. Methods: Individual cultures of E. faecalis and C. albicans as well as co-cultures of both were prepared in 1:1 mixture of brain heart infusion and RPMI media in high and low iron conditions. Growth curves were created for each culture. Biofilm formation of cultures was measured through crystal violet analysis. Sedimentation assay at OD600 was used to measure cellular aggregation. Cells were observed under microscope to view cellular interactions. Results: Regardless of iron levels, growth of C. albicans was reduced when grown in co-culture with E. faecalis (p < 0.0001). Biofilm formation was reduced in cocultures of E. faecalis and C. albicans under high iron conditions, OD600=2.13, compared low iron conditions, OD600=3.60 (p < 0.0001). Microscopy showed a lack of aggregation of E. faecalis along C. albicans hyphae. Conclusion: E. faecalis and C. albicans show an antagonistic relationship that restricts normal biofilm formation and growth in high iron conditions.