LAUSR

A biofilm is defined as adherent microbial communities on biotic or abiotic surfaces surrounded by extracellular polymeric substances (EPS) matrix. Biofilm formation by bacteria is very common; however, the pathogenic filamentous fungi and yeast also form biofilms. The microbial biofilm protects microbes against harsh environments, host immune defence and antibiotics. The composition and architecture of the fungal biofilms attribute tolerance to antifungal agents and require up to 10–1000 times greater concentrations of antifungal agents than planktonic cells to eradicate biofilms. In mature biofilms, the cell metabolism is slow and demonstrates differential gene expressions compared to the counterpart planktonic cells; therefore, the common antifungal agents are ineffective on active growing cells. The mode of growth of biofilms increases the frequency of genetic exchange, which results in the origin of an antibiotic-resistant strain. Polymicrobial biofilms of bacteria and fungi is another huge challenge in which cooperation between different species has been detected. The microbial biofilm infections are persisters and resistant to antibiotic therapy. The formation of biofilm is regulated by a process called quorum sensing (cell-to-cell communication) mediated by small molecules (auto-inducers). In animals, various infectious diseases, such as otomycosis, dermatitis, stomatitis, onychomycosis, vulvovaginitis, urinary tract infection and respiratory tract infection, are caused by biofilms of Candida spp., Cryptococcus spp., Malassezia spp., Trichosporon spp., Fusarium spp., Scedosporium spp., Lomentospora prolificans and Coccidioides spp. Animal disease caused by fungi forming biofilms is a huge challenge in veterinary medicine. In this review chapter, we provide an overview of biofilm-related fungi diseases of animals.