Pathogenic factors in Candida biofilm-related infectious diseases

Candida albicans is a commonly found member of the human microflora and is a major human opportunistic fungal pathogen. A perturbation of the microbiome can lead to infectious diseases caused by various micro-organisms, including C. albicans. Moreover, the interactions between C. albicans and bacteria are considered to play critical roles in human health. The major biological feature of C. albicans, which impacts human health, resides in its ability to form biofilms. In particular, the extracellular matrix (ECM) of Candida biofilm plays a multifaceted role and therefore may be considered as a highly attractive target to combat biofilm-related infectious diseases. In addition, extracellular DNA (eDNA) also plays a crucial role in Candida biofilm formation and its structural integrity and induces the morphological transition from yeast to the hyphal growth form during C. albicans biofilm development. This review focuses on pathogenic factors such as eDNA in Candida biofilm formation and its ECM production and provides meaningful information for future studies to develop a novel strategy to battle infectious diseases elicited by Candida-formed biofilm.

Effects of extracellular DNA from Candida albicans and pneumonia-related pathogens on Candida biofilm formation and hyphal transformation

AIMS

The aim of this study was to investigate the effects of genomic DNA purified from Candida albicans and pneumonia-related pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, on in vitro biofilm formation and morphological change of 3 Candida species (C. albicans, C. glabrata, and C. tropicalis).

METHODS AND RESULTS

Biofilm formation was evaluated by the crystal violet assay and colony-forming unit counts. Morphological characteristics of biofilms were evaluated by scanning electron microscopy and fluorescence microscopy. Addition of DNA at a low concentration (<1·0 μg ml(-1)) significantly increased biofilm mass of all three Candida species. In contrast, the addition of DNA at a high concentration (10 μg ml(-1)) decreased the biofilm mass. Interestingly, the formation of hyphae in a dense network of yeast cells was observed in C. albicans biofilms exposed to a low concentration of DNA (<1·0 μg ml(-1)).

CONCLUSIONS

These findings demonstrated that extracellular DNA (eDNA) plays a crucial role in Candida biofilm formation and suggested that eDNA may induce the morphological transition from yeast to hyphal growth form during C. albicans biofilm development.

SIGNIFICANCE AND IMPACT OF THE STUDY

A novel therapy targeting eDNA may be applicable for Candida infection to decrease biofilm formation and hyphal formation.