Resistance of
Candida albicans Biofilms to Drugs and the Host Immune System.
Jundishapur J Microbiol 2016;
9:e37385. [PMID:
28138373 PMCID:
PMC5240163 DOI:
10.5812/jjm.37385]
[Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 01/27/2023] Open
Abstract
Background
Candida albicans is a commensal fungus that resides on mucosal surfaces and in the gastrointestinal and genitourinary tracts in humans. However, it can cause an infection when the immune system of the host is impaired or if a niche becomes available. Many C. albicans infections are due to the organism’s ability to form a biofilm on implanted medical devices. A biofilm represents an optimal medium for the growth of C. albicans as it allows cells to be enclosed by a self-produced extracellular matrix (ECM).
Objectives
The present work investigated certain aspects of the resistance of C. albicans biofilms to drugs and the host immune system.
Results
An ECM was found to provide the infrastructure for biofilm formation, prevent disaggregation, and shield encapsulated C. albicans cells from antifungal drugs and the host’s immune system. By influencing FKS1 and upregulating multiple glucan modification genes, β-1, 3-glucan, an important component of ECM, was shown to be responsible for many of the biofilm’s drug-resistant properties. On being engulfed by ECM, the fungal cell was found to switch from glycolysis to gluconeogenesis. Resembling the cellular response to starvation, this was followed by the activation of the glyoxylate cycle that allowed the use of simple molecules as energy sources.
Conclusion
Mature biofilms were found to be much more resistant to antifungal agents and the host immune system than free cells. The factors responsible for high resistance included the complex architecture of biofilms, ECM, increased expression of drug efflux pumps, and metabolic plasticity.
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