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Published on: December 14, 2017
Candida albicans and Enterococcus faecalis biofilm frenemies: When the relationship sours
Om Alkhir Alshanta1, Khawlah Albashaireh1, Emily McKloud1
1Glasgow Endodontology and Oral Sciences Research Group, Glasgow Dental School, School of Medicine, Dentistry and Nursing, College of Medical, Veterinary and Life Sciences, Glasgow, United Kingdom.
Abstract:
The opportunistic yeast Candida albicans and lactic acid bacteria Enterococcus faecalis are frequently co-isolated from various infection sites on the human body, suggesting a common interkingdom interaction. While some reports suggest an antagonism, the reason for their co-isolation therefore remains unclear. The purpose of this study was to undertake a detailed characterisation of this dual-species interaction. We used standard biofilm characterisation methodologies alongside an RNASeq analysis to assess the response of C. albicans to E. faecalis. We evaluated the relevance of pH to dual-species biofilm interactions and demonstrated that E. faecalis rapidly and significantly impacted C. albicans morphogenesis and biofilm formation, which was mirrored by levels of gene expression. These transcripts were enriched in amino acids biosynthesis and metabolism pathways in co-cultures, a finding that guided our investigation into pH related mechanism. We were able to demonstrate the direct role of E. faecalis induced low pH, which inhibited C. albicans hyphal morphogenesis and biofilm formation. The results suggest that the anti-candidal effect of E. faecalis is not based solely on a single mechanism, instead it may involve various mechanisms, which collectively reflects the complexity of interaction between C. albicans and E. faecalis and impacts treatment outcomes.
Insights
Enterococcus faecalis rapidly impacts Candida albicans biofilm formation and morphogenesis by inducing a low pH environment. This interkingdom interaction involves multiple mechanisms, influencing treatment outcomes.
Area of Science:
- Microbiology
- Medical Mycology
- Bacterial Pathogenesis
Background:
- Candida albicans and Enterococcus faecalis are frequently co-isolated from human infections.
- The nature of their interaction and reasons for co-isolation remain unclear, despite reports of antagonism.
Purpose of the Study:
- To characterize the dual-species interaction between Candida albicans and Enterococcus faecalis.
- To investigate the impact of Enterococcus faecalis on Candida albicans biofilm formation and gene expression.
- To elucidate the role of pH in this interkingdom interaction.
Main Methods:
- Standard biofilm characterization techniques.
- RNASeq analysis to assess Candida albicans gene expression in response to Enterococcus faecalis.
- Evaluation of pH effects on dual-species biofilms.
Main Results:
- Enterococcus faecalis significantly impacted Candida albicans morphogenesis and biofilm formation.
- Gene expression analysis revealed enrichment in amino acid biosynthesis and metabolism pathways.
- A low pH induced by Enterococcus faecalis was identified as a key factor inhibiting Candida albicans hyphal growth and biofilm formation.
Conclusions:
- The anti-candidal effect of Enterococcus faecalis is multifactorial, involving pH-mediated inhibition.
- The complex interaction between Candida albicans and Enterococcus faecalis influences clinical outcomes.
- Understanding these mechanisms is crucial for developing effective treatment strategies.
