Journal Article

<i>Aspergillus fumigatus</i> enhances elastase production in <i>Pseudomonas aeruginosa</i> co-cultures

Karen Smith, Ranjith Rajendran, Stephen Kerr, David F. Lappin, William G. Mackay, Craig Williams and Gordon Ramage

in Medical Mycology

Published on behalf of International Society for Human and Animal Mycology

Volume 53, issue 7, pages 645-655
Published in print September 2015 | ISSN: 1369-3786
Published online July 2015 | e-ISSN: 1460-2709 | DOI:
Aspergillus fumigatus enhances elastase production in Pseudomonas aeruginosa co-cultures

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  • Infectious Diseases
  • Medical Toxicology
  • Environmental Science
  • Mycology and Fungi
  • Veterinary Medicine


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In the cystic fibrosis (CF) lung the presence of bacteria and fungi in the airways promotes an inflammatory response causing progressive lung damage, ultimately leading to high rates of morbidity and mortality. We hypothesized that polymicrobial interactions play an important role in promoting airway pathogenesis. We therefore examined the interplay between the most commonly isolated bacterial CF pathogen, Pseudomonas aeruginosa, and the most prevalent filamentous fungi, Aspergillus fumigatus, to test this. Co-culture experiments showed that in the presence of A. fumigatus the production of P. aeruginosa elastase was enhanced. This was confirmed by the presence of zones of clearance on Elastin-Congo Red (ECR) agar, which was identified as elastase by mass spectrometry. When P. aeruginosa were grown in a co-culture model with mature A. fumigatus biofilms, 60% of isolates produced significantly more elastase in the presence of the filamentous fungi than in its absence (P < .05). The expression of lasB also increased when P. aeruginosa isolates PA01 and PA14 were grown in co-culture with A. fumigatus. Supernatants from co-culture experiments were also significantly toxic to a human lung epithelial cell line (19–38% cell cytotoxicity) in comparison to supernatants from P. aeruginosa only cultures (P < .0001). Here we report that P. aeruginosa cytotoxic elastase is enhanced in the presence of the filamentous fungi A. fumigatus, suggesting that this may have a role to play in the damaging pathology associated with the lung tissue in this disease. This indicates that patients who have a co-colonisation with these two organisms may have a poorer prognosis.

Keywords: Pseudomonas; Aspergillus; biofilms; elastase; cystic fibrosis

Journal Article.  7804 words.  Illustrated.

Subjects: Infectious Diseases ; Medical Toxicology ; Environmental Science ; Mycology and Fungi ; Veterinary Medicine

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