Fungal Biofilms: Update on Resistance

Abstract

Over the past decade, the emergence of biofilm-related invasive fungal diseases has been the subject of numerous studies focused on antifungal resistance and its impact on antifungal therapy in severely ill patients. The majority of the studies investigated the molecular mechanisms involved in antifungal resistance and pathogenicity of biofilm production by Candida albicans and Aspergillus fumigatus, the most common etiologic agents of yeast and mold invasive infections. The main mechanism characterizing biofilm-related antifungal resistance is the production of extracellular matrix, a physical barrier preventing the drugs from entering and expressing their activity. However, over-expression of efflux pumps, genetic changes of drug targets, persister cells, biofilm-host immune system interaction, proteins leading to filamentation, all together contribute to the onset of biofilm antifungal resistance. Some of these mechanisms are shared with planktonic cells and are often related to developmental phases of biofilm formation. All physical and genetic factors leading to biofilm-related antifungal resistance have been briefly discussed.

The Anti-helminthic Compound Mebendazole Has Multiple Antifungal Effects against Cryptococcus neoformans

“…Biofilm formation causes well-known difficulties in the treatment of a number of infectious diseases, including cryptococcosis (Martinez and Casadevall, 2006; Borghi et al, 2016). Based on this observation, we evaluated whether co-incubation of mebendazole with yeast cells prevented C. neoformans biofilm formation or caused damage to mature biofilms.…”

Biofilm Formed by Candida haemulonii Species Complex: Structural Analysis and Extracellular Matrix Composition

“…Biofilm formation by the C. haemulonii species complex has already been reported based on the use of classical methodologies [1,7,16], but there is lack of information about the characteristics of the biofilm formed by these fungi. Indeed, it is believed that biofilm lifestyle is the preferred organization mode of microorganisms in nature, which is characterized by a highly complex structured community of microorganisms that interact with each other and with a biotic/abiotic surface, covered by a self-produced extracellular matrix (ECM) composed mainly of proteins, polysaccharides, lipids, nucleic acids, minerals, and water [17,18]. Functionally, the ECM plays an important role in the biofilm maintenance, architecture, and dynamic, being responsible for conferring protection against external stressors, such as host immune responses (both humoral and cellular components) and drugs (either disinfectants or antimicrobial agents), which directly impact the treatment, especially that of seriously ill patients [18,19].Biofilm-related infections are considered a huge problem in healthcare settings worldwide [20].…”

Exploring the anti-biofilm activity of cinnamic acid derivatives in Candida albicans

“…7 However, the antifungal resistance of C. albicans biofilm is complex and it involves not only the physical barrier due to the polysaccharide layer, but a number of different mechanisms, such as over-expression of efflux pumps, genetic changes of drug targets, persister cells, biofilm-host immune system interaction. 8 Azoles currently used for the treatment of systemic infections (e.g. fluconazole, itraconazole) have little effect against Candida biofilms, even at high doses and in combination with caspofungin.…”