Interactions between Bacteria and Aspergillus fumigatus in Airways: From the Mycobiome to Molecular Interactions

Abstract

Interactions between different kingdoms of microorganisms in humans are common but not well described. A recent analysis of the mycobiome has described the presence of different fungi and their positive and/or negative interactions with bacteria and other fungi. In chronic respiratory diseases, these different microorganisms form mixed biofilms to live inside. The interactions between Gram-negative bacteria and filamentous fungi in these biofilms have attracted more attention recently. In this review, we analyse the microbiota of the respiratory tract of healthy individuals and patients with chronic respiratory disease. Additionally, we describe the regulatory mechanisms that rule the mixed biofilms of Aspergillus fumigatus and Gram-negative bacteria and the effects of this biofilm on clinical presentations.

Keywords: Aspergillus fumigatus; Pseudomonas aeruginosa; Stenotrophomonas maltophilia; mixed biofilm; polymicrobial biofilms.

Figure 1

Conidiation and phenotype of A. fumigatus in the mixed biofilm visualised on SEM. (A) 24-h-old single A. fumigatus biofilm (A’) zoom on the presence of conidial head (B) 24-h-old mixed biofilm of A. fumigatus and S. maltophilia [25].

Figure 2

Cell wall thickness of A. fumigatus in mixed biofilms. (a) scale bar = 1 μm; (b) scale bar = 200 nm. Observation on 24 h ± old mixed biofilm by TEM. H = hyphae, B = bacteria, CW = cell wall, ECM = extracellular matrix (indicated by arrow) [25].

Figure 3

Synthesis of different mechanisms involved in bacteria–fungi interactions, particularly those between Gram-negative bacilli and Aspergillus fumigatus.