, 2010). The pulmonary cavity of CF patients with its thick mucous deposits predisposes to a wide range of opportunistic infections. A diverse microbial ecosystem has been described check details within the confined space of the lungs of CF patients, which is influenced by both the clinical status and the current antibiotic treatment regimens of the patient (Gilligan,
1991; Valenza et al., 2008). Indeed, a complex mixture of bacterial and fungal pathogens may coexist within the lungs, including Pseudomonas aeruginosa, Staphylococcus aureus, Burkholderia cenocepacia, Candida albicans and A. fumigatus (Valenza et al., 2008). Within this environment, both bacteria and fungi possess the ability to form multicellular biofilm consortia, making it inherently difficult to eradicate infection. In addition, direct physical contact between organisms or indirect molecular signalling interactions may influence microbial pathogenicity, which in turn may influence the disease MLN8237 outcome (Duan et al., 2003). Various studies have confirmed the presence of bacterial quorum-sensing molecules in the sputum of CF patients (Singh et al., 2000; Chambers et al., 2005). As these molecules are known to modulate
the pathogenicity of key CF-related pathogens, an investigation of the interactions between these microbial pathogens may provide novel treatment strategies. Our study reports on how direct and indirect interactions of the major prokaryotic CF pathogen P. aeruginosa, and associated molecules, with the eukaryotic pathogen A. fumigatus impact Rutecarpine on filamentous growth, leading to biofilm formation. Aspergillus fumigatus Af293 and four clinical isolates (YHCF1-4) obtained from the Royal Hospital for
Sick Children (Yorkhill Cystic Fibrosis Unit, Glasgow) were used throughout this study. Pseudomonas aeruginosa reference strains PAO1, PA14, ATCC 27835, six clinical nonclonal isolates [PA103, PA4384, PA14955, PA15861, PA16190 and PA16191 (gifted by Professor Douglas Storey, University of Calgary Foothills Hospital)] and two mutant strains [PAO1:ΔLasI (unable to synthesize N-acyl homoserine lactones (HSL)) and PAO1:ΔLasR (synthesizes HSL, but cannot respond), gifted by Professor Paul Williams, University of Nottingham] were used in this study. PAO1 mutants were maintained on Luria–Bertani (LB) broth agar plates containing 100 μg mL−1 ampicillin (Sigma-Aldrich, Gillingham, UK) and 20 μg mL−1 gentamicin (Sigma-Aldrich). All working stocks of fungal and bacterial strains were maintained at 4 °C on Sabouraud (Oxoid, Cambridge, UK) agar or LB agar slopes (Oxoid), respectively, and stored in Microbank® vials (Pro-Lab Diagnostics, Cheshire, UK) at −80 °C. For each assay, A. fumigatus was grown on Sabouraud agar and conidia standardized to 1 × 105 mL−1 in 3-(N-morpholino)propanesulphonic acid (MOPS)-buffered RPMI 1640 [pH 7.2 (Sigma-Aldrich)], as described previously by our group (Mowat et al., 2007).