Design of a Simple Model of Candida albicans Biofilms Formed under Conditions of Flow: Development, Architecture, and Drug Resistance
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Candida albicans biofilms on most medical devices are exposed to a flow of body fluids that provide water and nutrients to the fungal cells. While C. albicans biofilms grown in vitro under static conditions have been exhaustively studied, the same is not true for biofilms developed under continuous flow of replenishing nutrients. Here, we describe a simple flow biofilm (FB) model that can be built easily with materials commonly available in most microbiological laboratories. We demonstrate that C. albicans biofilms formed using this flow system show increased architectural complexity compared to biofilms grown under static conditions. C. albicans biofilms under continuous medium flow grow rapidly, and by 8 h show characteristics similar to 24 h statically grown biofilms. Biomass measurements and microscopic observations further revealed that after 24 h of incubation, FB was more than twofold thicker than biofilms grown under static conditions. Microscopic analyses revealed that the surface of these biofilms was extremely compact and wrinkled, unlike the open hyphal layer typically seen in 24 h static biofilms. Results of antifungal drug susceptibility tests showed that C. albicans cells in FB exhibited increased resistance to most clinically used antifungal agents.
KeywordsCandida albicans Biofilm Flow Shear stress
Work in the laboratory is supported by Public Health Service grants numbered RO1 AI 064562 from the National Institute of Allergy and Infectious Diseases and R21 DE 017294 from the National Institute of Dental and Craniofacial Research to J. L. Lopez-Ribot. We would like to thank the Research Center for Minority Institutions (RCMI) Advance Imaging Center, supported by Grant numbered 5G12 RR01 3646-10, for use of the confocal microscope, and Colleen Witt for assistance with confocal microscopy. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute of Allergy and Infectious Diseases, the National Institute of Dental and Craniofacial Research, or the National Institutes of Health.
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