Drug resistance mechanisms of fungal biofilms

Abstract

Fungi are ubiquitous in nature and exist in soil, water, plants, and in animals and humans. Similar to bacteria, fungi also form confluent biofilms either singly (mono-species) or with other microbial species (mixed-species). Fungal biofilms are known to be highly resistant to the adverse environmental conditions including antimicrobials and biocide compared to its planktonic (free-floating) counterparts. Although bacterial biofilms have been studied in detail, relatively little is known of fungal biofilms, its properties and their role in infections. Fungal biofilm infections, particular caused by Candida species have dramatically increased in the past decade due to increased numbers of compromised populations such as HIV/AIDS patients, organ transplant recipients and patients on chemotherapy. Candida biofilm associated infections are frequently refractory to antifungal agents owing to the properties that are unique to the biofilm phenotype. Although various hypotheses have been proposed for the higher antifungal resistance of Candida biofilms, the exact mechanism is still elusive. Therefore, in this chapter, we review the current knowledge on the drug resistance mechanisms of fungal biofilms, focusing on that of Candida biofilms. We will also outline in brief, the technological platforms available to investigate such properties in fungal biofilms. Lastly we summarize areas that warrant further research in the field of fungal biofilms.