Aspergillus Biofilms in Human Disease

Abstract

The biofilm phenotype of Aspergillus species is an important and accepted clinical entity. While industrially these biofilms have been used extensively in important biofermentations, their role in clinical infection is less well defined. A recent flurry of activity has demonstrated that these interesting filamentous moulds have the capacity to form biofilms both in vitro and in vivo, and through various investigations have shown that these are exquisitely resistant to antifungal therapies through a range of adaptive resistance mechanisms independent of defined genetic changes. This review will explore the clinical importance of these biofilms and provide contemporary information with respect to their clinical management.

Developmental stages of biofilm and characterization of extracellular matrix of manglicolous fungus Aspergillus niger BSC‐1

“…Due to several unique features related to fungal biology, biofilm formation by filamentous fungus is quite different from that of bacteria and yeast. species are involved in several systemic and superficial infections such as aspergilloma, invasive pulmonary aspergillosis, allergic bronchopulmonary aspergillosis, and even systemic dissemination [36]. In pathogenic fungi, the formation of biofilm is considered as an important virulence factor protecting against antimicrobials and environmental stressors.…”

“…To determine biofilm formation by A. niger BSC-1, microtiter plate assay was performed at different time interval using a six-well flat-bottomed polystyrene microtiter plate [13]. In brief, equal volume of conidial suspension (10 6 conidia/ml) was inoculated to 3 ml of potato infusion broth and incubated statically for 4,8,12,16,20,24,36,48,60, and 72 h at 25°C. At each time interval, the culture broth was aspirated from the well followed by washing with sterile 1× PBS for three times to remove the planktonic cells.…”

“…The stages of fungal biofilm development were analyzed by field emission scanning electron microscopy (FESEM) micrograph. The biofilm was developed in a six-well flatbottomed polystyrene microtiter plate with glass coverslip (8 × 8 mm; Blue Star) for 4,8,12,16,20,24,36,48,60, and 72 h at 25°C as described above. For FESEM analysis, the biofilm attached to the coverslips was washed with 1× PBS at each time interval followed by fixation with 2.5% glutaraldehyde for 4 h at 4°C.…”

“…To observe different stages of fungal biofilm under confocal laser scanning microscopy (CLSM), biofilm were formed on the surface of sterile glass coverslips dipped in 10 ml of potato infusion broth. After incubation for different time intervals (4,8,12,16,20,24,36,48,60, and 72 h), the coverslips were washed with 1× PBS and stained with various fluorescence dye. For analysis of ECM and cells, the biofilm was stained with 10 μM of FUN®1 dye (Thermo Fisher Scientific) followed by 300 mg/L of Calcofluor white (Thermo Fisher Scientific) for 20 min under dark conditions.…”

Pathogenesis of Fungal Infections in Cystic Fibrosis

“…Aspergillus is recognised bronchoscopically by the production of mucus plugs, which may be due to the production of glycan polymers. The ECM includes the polysaccharides, galactomannan, galactosaminogalactan, α-1,3 glucans, monosaccharides, proteins, melanin and extracellular DNA [66, 84]. The Aspergillus galactosaminogalactan allows adherence to host constituents and conceals hyphal beta-glucan from the immune system [25, 26], and the extracellular DNA is important for protection from environmental stresses, including antifungal therapy [64].…”