Fungal Biofilms and Polymicrobial Diseases

Abstract

Biofilm formation is an important virulence factor for pathogenic fungi. Both yeasts and filamentous fungi can adhere to biotic and abiotic surfaces, developing into highly organized communities that are resistant to antimicrobials and environmental conditions. In recent years, new genera of fungi have been correlated with biofilm formation. However, Candida biofilms remain the most widely studied from the morphological and molecular perspectives. Biofilms formed by yeast and filamentous fungi present differences, and studies of polymicrobial communities have become increasingly important. A key feature of resistance is the extracellular matrix, which covers and protects biofilm cells from the surrounding environment. Furthermore, to achieve cell–cell communication, microorganisms secrete quorum-sensing molecules that control their biological activities and behaviors and play a role in fungal resistance and pathogenicity. Several in vitro techniques have been developed to study fungal biofilms, from colorimetric methods to omics approaches that aim to identify new therapeutic strategies by developing new compounds to combat these microbial communities as well as new diagnostic tools to identify these complex formations in vivo. In this review, recent advances related to pathogenic fungal biofilms are addressed.

In vitro efficacy of garlic extract against Candida albicans biofilms from children with early childhood caries

“…C. albicans biofilms are unique and substantially differ from bacterial biofilms containing hyphae and pseudohyphae. Their properties are remarkably different from those of planktonic or free-living populations, most notably regarding their high-level resistance to most antifungal agents [4,5]. C. albicans biofilms can mature and increase in complexity within 24-48 h, the development of which begins with small microcolonies comprising budding yeast cells that later transform into filaments, forming pseudohyphae and true hyphae.…”

“…The discordance between the present and previous studies may be attributed to the different types of tests and biofilm development. The MTT assay, a colorimetric assay commonly used in studies on the susceptibility of biofilms to antifungal drugs, was used in the present study [4]. MTT, a yellow tetrazolium salt, is further reduced to insoluble purple formazan crystals in the presence of metabolic activity, indicating the percentage of viable cells [4,16,17].…”

“…The formation continues with the early development of basal layers of yeast cells, hyphae, and extracellular matrix. Mature biofilms contain a substantial number of yeast cells, hyphae, pseudohyphae, extracellular matrix, and water channels that facilitate the movement of nutrients and cell distribution [4]. Mature forms of C. albicans biofilms have proven resistant to a variety of conventional antifungal drugs, leading to ineffective treatment [5].…”

Nano Based Therapy for Biofilm Management: Mini Review

“…Furthermore, the application of low energy ion irradiation (10 12 -10 16 ion/cm 2 ) can also be performed to enhance the physicochemical properties of the QDs and in turn their antifungal potency. Literature states that both biofilm and hyphal formation are important factors that are associated with drug resistivity and virulence [18]. This invariability makes drug resistance traits and virulence traits as crucial and novel high value targets for suppressing microbial infections.…”

Antimicrobial Metal Nanomaterials: From Passive to Stimuli‐Activated Applications

“…[ 16 ] As with bacteria, many fungi can adhere to biotic and abiotic surfaces, presenting as a challenge for removal of the biofilm communities. [ 17,18 ] For example, Candida species were found to be the fourth most common pathogen causing hospital‐acquired bloodstream infection in the USA, [ 19 ] with around 400 000 cases a year worldwide, which are often associated with implanted medical devices. [ 20 ] Antifungal drugs predominately target the disruption of the biosynthesis pathways or integrity of important components of the fungal cell wall.…”