Interspecific small molecule interactions between clinical isolates of Pseudomonas aeruginosa and Staphylococcus aureus from adult cystic fibrosis patients.

Alexandre Fugère (1) , David Lalonde Séguin (1) , Gabriel Mitchell (1) , Eric Déziel (2) , Valérie Dekimpe (2) , André M Cantin (3) , Eric Frost (4) , François Malouin (1)

1 CEVDM - Centre d'Étude et de Valorisation de la Diversité Microbienne . Département de biologie
2 INRS-IAF - Institut Armand Frappier
3 Service de pneumologie, Département de médecine
4 Département de Microbiologie et d'Infectiologie

Pseudomonas aeruginosa and Staphylococcus aureus are the most prevalent pathogens in airway infections of cystic fibrosis (CF) patients. We studied how these pathogens coexist and interact with each other. Clinical isolates of both species were retrieved from adult CF patients. Culture supernatants from 63 P. aeruginosa isolates triggered a wide range of biofilm-stimulatory activities when added to the culture of a control S. aureus strain. The extent of biofilm formation by S. aureus was positively correlated to the levels of the 2-alkyl-4-(1H)-quinolones (AQs) Pseudomonas Quinolone Signal (PQS) and 2-heptyl-4-hydroxy quinoline N-oxide (HQNO) produced by the P. aeruginosa isolates. Supernatants from P. aeruginosa isogenic mutants deficient in PQS and HQNO production stimulated significantly less biofilm formation by S. aureus than that seen with the parental strain PA14. When studying co-isolated pairs of P. aeruginosa and S. aureus retrieved from patients showing both pathogens, P. aeruginosa supernatants stimulated less biofilm production by the S. aureus counterparts compared to that observed using the control S. aureus strain. Accordingly, some P. aeruginosa isolates produced low levels of exoproducts and also some of the clinical S. aureus isolates were not stimulated by their co-isolates or by PA14 despite adequate production of HQNO. This suggests that colonization of the CF lungs promotes some type of strain selection, or that co-existence requires specific adaptations by either or both pathogens. Results provide insights on bacterial interactions in CF.

Domaines: Sciences du Vivant [q-bio]; Biochimie, Biologie Moléculaire; Bactériologie

Alexandre Fugère, David Lalonde Séguin, Gabriel Mitchell, Eric Déziel, Valérie Dekimpe, et al.. Interspecific small molecule interactions between clinical isolates of Pseudomonas aeruginosa and Staphylococcus aureus from adult cystic fibrosis patients.. PLoS ONE, 2014, 9 (1), pp.e86705. ⟨10.1371/journal.pone.0086705⟩. ⟨pasteur-01135620⟩