Assessment of Biofilm Formation by Candida albicans Strains Isolated from Hemocultures and Their Role in Pathogenesis in the Zebrafish Model

Abstract

Candida albicans, an opportunistic pathogen, has the ability to form biofilms in the host or within medical devices in the body. Biofilms have been associated with disseminated/invasive disease with increased severity of infection by disrupting the host immune response and prolonging antifungal treatment. In this study, the in vivo virulence of three strains with different biofilm formation strengths, that is, non-, weak-, and strong biofilm formers, was evaluated using the zebrafish model. The survival assay and fungal tissue burden were measured. Biofilm-related gene expressions were also investigated. The survival of zebrafish, inoculated with strong biofilms forming C. albicans,, was significantly shorter than strains without biofilms forming C. albicans. However, there were no statistical differences in the burden of viable colonogenic cell number between the groups of the three strains tested. We observed that the stronger the biofilm formation, the higher up-regulation of biofilm-associated genes. The biofilm-forming strain (140 and 57), injected into zebrafish larvae, possessed a higher level of expression of genes associated with adhesion, attachment, filamentation, and cell proliferation, including eap1, als3, hwp1, bcr1, and mkc1 at 8 h. The results suggested that, despite the difference in genetic background, biofilm formation is an important virulence factor for the pathogenesis of C. albicans. However, the association between biofilm formation strength and in vivo virulence is controversial and needs to be further studied.

Alterations in the Level of Ergosterol in Candida albicans’ Plasma Membrane Correspond with Changes in Virulence and Result in Triggering Diversed Inflammatory Response

“…One of the key virulence factors of C. albicans is its ability to form biofilms both on biotic and abiotic surfaces, which can be critical for patients after transplantations [ 37 ]. Here, the biofilm formation assay analysis revealed that C. albicans KS058 has an impaired ability of biofilm formation ( Figure 1 B).…”

Characterization of Oral Candida spp. Biofilms in Children and Adults Carriers from Eastern Europe and South America

“…In this study, the biofilms' comparisons were made while taking into account C. albicans SC5314 biofilm, which has high hyphae quantity and entanglement [8,11]. The results showed that all of the strains were biofilm formers, regardless of the age group.…”

“…These concentrations were carefully chosen, taking into account several previous studies conducted by our group with the same conditions (antifungal drugs used to treat matured biofilms of Candida spp.) [10][11][12][13][14][15].…”

“…It is relevant to indicate that these concentrations were chosen, according to previous studies of our group, as the minimum concentrations to eradicate the biofilm (MBEC) in several Candida spp. [8,[10][11][12][13][14][15]. Wells containing only culture medium without inoculum were used as negative control.…”

Our current clinical understanding of Candida biofilms: where are we two decades on?

“…It has been successfully used for investigating immune responses to both yeast and mould systemic infections (204). In a recent study, C. albicans isolates, with a high or low propensity to form biofilms, were injected in zebrafish larvae to assess in vivo virulence (205). Although fish survival after strong biofilm‐former isolates was significantly reduced, fungal burden was similar after tissue recovery.…”