Investigating the role of matrix components in protection of Burkholderia cepacia complex biofilms against tobramycin

Messiaen, Anne-Sophie; Nelis, Hans; Coenye, Tom

doi:10.1016/j.jcf.2013.07.004

Cited by 42 publications

(26 citation statements)

References 30 publications

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“…Protection is diminished by the addition of cationic agents, indicating that eDNA may retard penetration of tobramycin into biofilms through ionic interactions. However, treatment of Burkholderia cepacia complex biofilms with recombinant human DNase did not increase sensitivity to tobramycin [55]. It is possible that polysaccharides are more important for interactions with cationic agents in B. cepacia complex biofilms, or that the eDNA within B. cepacia complex biofilms is protected from DNase digestion by DNA-binding proteins.…”

Section: Protection Against Antimicrobial Agentsmentioning

confidence: 95%

Extracellular DNA in oral microbial biofilms

Jakubovics

Burgess

2015

Microbes and Infection

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Section: Protection Against Antimicrobial Agentsmentioning

confidence: 95%

Extracellular DNA in oral microbial biofilms

Jakubovics

Burgess

2015

Microbes and Infection

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“…For example, the RNA-binding protein CsrA (carbon storage regulator A) negatively regulates pgaA translation, pgaABCD transcription, and mRNA stability (16,26,27 29 solved the crystal structure of AlgK. In combination with functional analyses, they proposed a mechanism for alginate secretion across the bacterial outer membrane; Little et al (23,24) reported the crystal structures of PgaB and its complex with ␤-1,6-(GlcNAc) 6 and disclosed the catalytic mechanism of the N-deacetylase PgaB on PNAG polymers and the manner of periplasmic translocation of PNAG. Despite this progress, many questions regarding how dPNAG, an essential biofilmsupporting exopolysaccharide, is polymerized and translocated across the bacterial outer membrane remain to be answered.…”

mentioning

confidence: 99%

Structural Basis for Translocation of a Biofilm-supporting Exopolysaccharide across the Bacterial Outer Membrane

Wang

Pannuri

et al. 2016

Journal of Biological Chemistry

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The partially de-N-acetylated poly-␤-1,6-N-acetyl-D-glucosamine (dPNAG) polymer serves as an intercellular biofilm adhesin that plays an essential role for the development and maintenance of integrity of biofilms of diverse bacterial species. Translocation of dPNAG across the bacterial outer membrane is mediated by a tetratricopeptide repeat-containing outer membrane protein, PgaA. To understand the molecular basis of dPNAG translocation, we determined the crystal structure of the C-terminal transmembrane domain of PgaA (residues 513-807). The structure reveals that PgaA forms a 16-strand transmembrane ␤-barrel, closed by four loops on the extracellular surface. Half of the interior surface of the barrel that lies parallel to the translocation pathway is electronegative, suggesting that the corresponding negatively charged residues may assist the secretion of the positively charged dPNAG polymer. In vivo complementation assays in a pgaA deletion bacterial strain showed that a cluster of negatively charged residues proximal to the periplasm is necessary for biofilm formation. Biochemical analyses further revealed that the tetratricopeptide repeat domain of PgaA binds directly to the N-deacetylase PgaB and is critical for biofilm formation. Our studies support a model in which the positively charged PgaB-bound dPNAG polymer is delivered to PgaA through the PgaA-PgaB interaction and is further targeted to the ␤-barrel lumen of PgaA potentially via a charge complementarity mechanism, thus priming the translocation of dPNAG across the bacterial outer membrane.

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“…However, chronic suppression of B. cepacia complex biofilm growth may be possible and may result in clinical benefits to CF patients, as has been shown with chronic suppressive treatment of Pseudomonas aeruginosa pulmonary infections in CF (23). Alteration of the tobramycin formulation, either through high-efficiency encapsulation into neutrally charged li- posomes (24) or through combination with a matrix-degrading compound (25), may improve its antimicrobial activity against B. cepacia complex biofilms. This current model system represents an innovative way of visualizing the antimicrobial activity of novel therapeutics against bacterial biofilms.…”

Section: Discussionmentioning

confidence: 99%

Activity of Tobramycin against Cystic Fibrosis Isolates of Burkholderia cepacia Complex Grown as Biofilms

Kennedy

Beaudoin

Yau

et al. 2016

Antimicrob Agents Chemother

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f Pulmonary infection with Burkholderia cepacia complex in cystic fibrosis (CF) patients is associated with more-rapid lung function decline and earlier death than in CF patients without this infection. In this study, we used confocal microscopy to visualize the effects of various concentrations of tobramycin, achievable with systemic and aerosolized drug administration, on mature B. cepacia complex biofilms, both in the presence and absence of CF sputum. After 24 h of growth, biofilm thickness was significantly reduced by exposure to 2,000 g/ml of tobramycin for Burkholderia cepacia, Burkholderia multivorans, and Burkholderia vietnamiensis; 200 g/ml of tobramycin was sufficient to reduce the thickness of Burkholderia dolosa biofilm. With a more mature 48-h biofilm, significant reductions in thickness were seen with tobramycin at concentrations of >100 g/ml for all Burkholderia species. In addition, an increased ratio of dead to live cells was observed in comparison to control with tobramycin concentrations of >200 g/ml for B. cepacia and B. dolosa (24 h) and >100 g/ml for Burkholderia cenocepacia and B. dolosa (48 h). Although sputum significantly increased biofilm thickness, tobramycin concentrations of 1,000 g/ml were still able to significantly reduce biofilm thickness of all B. cepacia complex species with the exception of B. vietnamiensis. In the presence of sputum, 1,000 g/ml of tobramycin significantly increased the dead-to-live ratio only for B. multivorans compared to control. In summary, although killing is attenuated, high-dose tobramycin can effectively decrease the thickness of B. cepacia complex biofilms, even in the presence of sputum, suggesting a possible role as a suppressive therapy in CF.

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Investigating the role of matrix components in protection of Burkholderia cepacia complex biofilms against tobramycin

Abstract: These results suggest that EPS play a role in tobramycin susceptibility of Bcc biofilms and that matrix degrading combination therapy could improve treatment of Bcc biofilm infections.

Cited by 42 publications

References 30 publications

Extracellular DNA in oral microbial biofilms

Extracellular DNA in oral microbial biofilms

Structural Basis for Translocation of a Biofilm-supporting Exopolysaccharide across the Bacterial Outer Membrane

Activity of Tobramycin against Cystic Fibrosis Isolates of Burkholderia cepacia Complex Grown as Biofilms

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