Biofilm Formation by Pseudallescheria/Scedosporium Species: A Comparative Study

Abstract

Pseudallescheria/Scedosporium species are medically important fungi that are present in soil and human impacted areas and capable of causing a wide spectrum of diseases in humans. Although little is known about their pathogenesis, their growth process and infection routes are very similar to those of Aspergillus species, which grow as biofilms in invasive infections. All nine strains tested here displayed the ability to grow as biofilms in vitro and to produce a dense network of interconnected hyphae on both polystyrene and the surfaces of central venous catheters, but with different characteristics. Scedosporium boydii and S. aurantiacum clinical isolates were able to form biofilms faster than the corresponding environmental strains, as evidenced in kinetic assays for S. boydii and CLSM for S. aurantiacum. Biofilms formed by Pseudallescheria/Scedosporium species had significantly higher resistance to the class of antifungal azole than was observed in planktonic cells, indicating a protective role for this structure. In addition, the clinical S. aurantiacum isolate that formed the most robust biofilms was also more virulent in a larvae Galleria mellonella infection model, suggesting that the ability to form biofilms enhances virulence in Pseudallescheria/Scedosporium species.

Therapeutic Challenges of Non- Aspergillus Invasive Mold Infections in Immunosuppressed Patients

“…The activity of all antifungal drug classes was shown to be considerably decreased against sessile biofilms of Aspergillus fumigatus on bronchial epithelial cells (42). Similarly, Scedosporium spp., which are frequent persistent colonizers in patients with cystic fibrosis, are able to form biofilms with decreased susceptibility to antifungals and possibly higher virulence (43). Biofilm formation has also been described for Fusarium spp.…”

<p>Tryptophol Coating Reduces Catheter-Related Cerebral and Pulmonary Infections by <em>Scedosporium apiospermum</em></p>

“…[9][10][11] Furthermore, the increased incidence of S. apiospermum infections was reported to be because of the extensive use of corticosteroids, immunosuppressants, antineoplastics, broad-spectrum antibiotics, and indwelling catheters including long-term CVC. 1,[12][13][14][15][16] In some cases, S. apiospermum infections following medical intervention were isolated from the insertion site of a catheter, indicating a significant evidence of nosocomial diseases. 13 The recent study has exhibited that S. apiospermum can form biofilms on the surface of both polystyrene and polyurethane, a material of CVC.…”

Saccharide sources do not influence the biofilm formation in Scedosporium/Lomentospora species

“…Biofilm is considered a microbial community adhered to a biotic/abiotic surface covered by a complex extrapolymeric substance, which confers resistance to environmental stresses (Flemming et al, 2016). Scedosporium and Lomentospora species form biofilm structures over different substrates, including polystyrene, glass, catheters and lung epithelial cells, which present a typical multidrug-resistance profile (Mello et al, 2016(Mello et al, , 2018Rollin-Pinheiro et al, 2017). However, little is known about the environmental conditions that interfere with the biofilm formation in these fungi.…”