Chronic, highly antibiotic-resistant infections in cystic fibrosis (CF) lungs contribute to increasing morbidity and mortality.
Cystic fibrosis (CF) patients often experience chronic, debilitating lung infections caused by antibiotic-resistant
Bacterial infections in cystic fibrosis (CF) patients are an emerging health issue and lead to a premature death. CF is a hereditary disease that creates a thick mucus in the lungs that is prone to bacterial biofilm formation, specifically
- Award ID(s):
- 1715494
- NSF-PAR ID:
- 10255871
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemBioChem
- Volume:
- 22
- Issue:
- 9
- ISSN:
- 1439-4227
- Page Range / eLocation ID:
- p. 1646-1655
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Introduction Chronic lung infection due to bacterial biofilms is one of the leading causes of mortality in cystic fibrosis (CF) patients. Among many species colonizing the lung airways,
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O'Toole, George (Ed.)ABSTRACT The biofilm matrix is composed of exopolysaccharides, eDNA, membrane vesicles, and proteins. While proteomic analyses have identified numerous matrix proteins, their functions in the biofilm remain understudied compared to the other biofilm components. In the Pseudomonas aeruginosa biofilm, several studies have identified OprF as an abundant matrix protein and, more specifically, as a component of biofilm membrane vesicles. OprF is a major outer membrane porin of P. aeruginosa cells. However, current data describing the effects of OprF in the P. aeruginosa biofilm are limited. Here, we identify a nutrient-dependent effect of OprF in static biofilms, whereby Δ oprF cells form significantly less biofilm than wild type when grown in media containing glucose or low sodium chloride concentrations. Interestingly, this biofilm defect occurs during late static biofilm formation and is not dependent on the production of PQS, which is responsible for outer membrane vesicle production. Furthermore, while biofilms lacking OprF contain approximately 60% less total biomass than those of wild type, the number of cells in these two biofilms is equivalent. We demonstrate that P. aeruginosa Δ oprF biofilms with reduced biofilm biomass contain less eDNA than wild-type biofilms. These results suggest that the nutrient-dependent effect of OprF is involved in the maintenance of P. aeruginosa biofilms by retaining eDNA in the matrix. IMPORTANCE Many pathogens form biofilms, which are bacterial communities encased in an extracellular matrix that protects them against antibacterial treatments. The roles of several matrix components of the opportunistic pathogen Pseudomonas aeruginosa have been characterized. However, the effects of P. aeruginosa matrix proteins remain understudied and are untapped potential targets for antibiofilm treatments. Here, we describe a conditional effect of the abundant matrix protein OprF on late-stage P. aeruginosa biofilms. A Δ oprF strain formed significantly less biofilm in low sodium chloride or with glucose. Interestingly, the defective Δ oprF biofilms did not exhibit fewer resident cells but contained significantly less extracellular DNA (eDNA) than wild type. These results suggest that OprF is involved in matrix eDNA retention in biofilms.more » « less
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Abstract Objectives To assess the ability of oxyclozanide to enhance tobramycin killing of Pseudomonas aeruginosa biofilms and elucidate its mechanism of action.
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Results Here we show that the ionophore anthelmintic oxyclozanide, combined with tobramycin, significantly increased killing of P. aeruginosa biofilms over each treatment alone. This combination also significantly accelerated the killing of cells within biofilms and stationary phase cultures and it was effective against 4/6 CF clinical isolates tested, including a tobramycin-resistant strain. Oxyclozanide enhanced the ability of additional aminoglycosides and tetracycline to kill P. aeruginosa biofilms. Finally, oxyclozanide permeabilized cells within the biofilm, reduced the membrane potential and increased tobramycin accumulation within cells of mature P. aeruginosa biofilms.
Conclusions Oxyclozanide enhances aminoglycoside and tetracycline activity against P. aeruginosa biofilms by reducing membrane potential, permeabilizing cells and enhancing tobramycin accumulation within biofilms. We propose that oxyclozanide counteracts the adaptive resistance response of P. aeruginosa to aminoglycosides, increasing both their maximum activity and rate of killing. As oxyclozanide is widely used in veterinary medicine for the treatment of parasitic worm infections, this combination could offer a new approach for the treatment of biofilm-based P. aeruginosa infections, repurposing oxyclozanide as an anti-biofilm agent.
