Epitopes in the capsular polysaccharide and the porin OmpK36 receptors are required for bacteriophage infection of Klebsiella pneumoniae

Dunstan, Rhys A.; Bamert, Rebecca S.; Tan, Kian L.; Imbulgoda, Uvini; Barlow, Christopher K.; Taiaroa, George; Pickard, Derek; Schittenhelm, Ralf B.; Dougan, Gordon; Short, Francesca L.; Lithgow, Trevor

doi:10.1016/j.celrep.2023.112551

Cited by 9 publications

(5 citation statements)

References 97 publications

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“…We can conclude that more charged groups in LPS favor proper LPS-LPS interactions avoiding the collapse toward the trimer, that would inhibit important functional interaction of loops with molecules from the extracellular side. [59,60] The comparison of the polarization density of our water probe for the three systems showed that the presence of LPS and calcium ions has only minor effects on both the transversal and longitudinal components inside the monomers, Figure 4. Moreover, the polarization density above the extracellular mouth, that region surrounded by LPS chains and calcium ions, is zero, as expected also by symmetry.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Lipopolysaccharides on the Electrostatic Properties of Gram‐Negative General Porins from Enterobacteriaceae

Ceccarelli,

Milenkovic,

Bodrenko

2024

ChemPhysChem

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We investigated, by using all‐atom molecular dynamics simulations, the effect of the asymmetric outer membrane layer of Gram‐negative bacteria, composed in the outer leaflet by polar/charged lipopolysaccharides (LPS), on the electrostatic properties of general porins from the Enterobacteriaceae family. These porins constitute the main path for the facilitated diffusion of polar antibiotics to cross the outer membrane. As model system we selected OmpK36 from Klebsiella pneumoniae, the ortholog of OmpC from Escherichia coli. This species presents high variability of amino acid composition of porins, with the effect to increase its resistance to the penetration of antibiotics. The various properties we analyzed seem to indicate that LPS acts as an independent layer without affecting the internal electrostatic properties of OmpK36. The only apparent effect at this time scale is the appearance of calcium ions, when present at moderate concentration in solution, inside the pore, though we noticed only increased fluctuations of the polarization density and slight changes on its average value.

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Section: Discussionmentioning

confidence: 99%

The Effect of Lipopolysaccharides on the Electrostatic Properties of Gram‐Negative General Porins from Enterobacteriaceae

Ceccarelli,

Milenkovic,

Bodrenko

2024

ChemPhysChem

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“…In future, use of β-1,3-glucanase to degrade β-1,3-glucan, one of the most important matrix polysaccharides in C. albicans biofilms, may be a more appropriate candidate for testing (98, 99). Similarly, trials could be established with the use of bacteriophage-derived hydrolases that degrade the capsular polysaccharide of K. pneumoniae strains such as B5055 (100, 101).…”

Section: Discussionmentioning

confidence: 99%

A new model of endotracheal tube biofilm identifies combinations of matrix-degrading enzymes and antimicrobials able to eradicate biofilms of pathogens that cause ventilator-associated pneumonia

Walsh,

Parmenter,

Bakker

et al. 2024

Preprint

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Defined as a pneumonia occurring after more than 48 hours of mechanical ventilation via an endotracheal tube, ventilator-associated pneumonia results from biofilm formation on the indwelling tube, seeding the patient’s lower airways with pathogenic microbes such asPseudomonas aeruginosa, Klebsiella pneumoniae,andCandida albicans.Currently there is a lack of accuratein vitromodels of ventilator-associated pneumonia development. This greatly limits our understanding of how the in-host environment alters pathogen physiology and the efficacy of ventilator-associated pneumonia prevention or treatment strategies. Here, we showcase a reproducible model that simulates biofilm formation of these pathogens in a host-mimicking environment, and demonstrate that the biofilm matrix produced differs from that observed in standard laboratory growth medium. In our model, pathogens are grown on endotracheal tube segments in the presence of a novel synthetic ventilator airway mucus (SVAM) medium that simulates the in-host environment. Matrix-degrading enzymes and cryo-SEM were employed to characterise the system in terms of biofilm matrix composition and structure, as compared to standard laboratory growth medium. As seen in patients, the biofilms of ventilator-associated pneumonia pathogens in our model either required very high concentrations of antimicrobials for eradication, or could not be eradicated. However, combining matrix-degrading enzymes with antimicrobials greatly improved biofilm eradication of all pathogens. Ourin vitroendotracheal tube (IVETT) model informs on fundamental microbiology in the ventilator-associated pneumonia context, and has broad applicability as a screening platform for antibiofilm measures including the use of matrix-degrading enzymes as antimicrobial adjuvants.ImportanceThe incidence of ventilator-associated pneumonia in mechanically ventilated patients is between 5-40%, increasing to 50-80% in patients suffering from coronavirus disease 2019 (COVID-19). The mortality rate of ventilator-associated pneumonia patients can reach 45%. Treatment of the endotracheal tube biofilms that cause ventilator-associated pneumonia is extremely challenging, with causative organisms able to persist in endotracheal tube biofilm despite appropriate antimicrobial treatment in 56% of ventilator-associated pneumonia patients. Flawed antimicrobial susceptibility testing often means that ventilator-associated pneumonia pathogens are insufficiently treated, resulting in patients experiencing ventilator-associated pneumonia recurrence. Here we present anin vitroendotracheal tube biofilm model that recapitulates key aspects of endotracheal tube biofilms, including dense biofilm growth and elevated antimicrobial tolerance. Thus our biofilm model can be used as a ventilated airway simulating environment, aiding the development of anti-ventilator-associated pneumonia therapies and antimicrobial endotracheal tubes that can one day improve the clinical outcomes of mechanically ventilated patients.

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“…In the future, the use of β−1,3-glucanase to degrade β−1,3-glucan, one of the most important matrix polysaccharides in C. albicans biofilms, maybe a more appropriate candidate for testing [107,108]. Similarly, trials could be established with the use of bacteriophage-derived hydrolases that degrade the capsular polysaccharide of K. pneumoniae strains such as B5055 [109,110].…”

Section: Discussionmentioning

confidence: 99%

A new model of endotracheal tube biofilm identifies combinations of matrix-degrading enzymes and antimicrobials able to eradicate biofilms of pathogens that cause ventilator-associated pneumonia

Walsh,

Parmenter,

Bakker

et al. 2024

Microbiology

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Ventilator-associated pneumonia is defined as pneumonia that develops in a patient who has been on mechanical ventilation for more than 48 hours through an endotracheal tube. It is caused by biofilm formation on the indwelling tube, which introduces pathogenic microbes such as Pseudomonas aeruginosa, Klebsiella pneumoniae and Candida albicans into the patient’s lower airways. Currently, there is a lack of accurate in vitro models of ventilator-associated pneumonia development. This greatly limits our understanding of how the in-host environment alters pathogen physiology and the efficacy of ventilator-associated pneumonia prevention or treatment strategies. Here, we showcase a reproducible model that simulates the biofilm formation of these pathogens in a host-mimicking environment and demonstrate that the biofilm matrix produced differs from that observed in standard laboratory growth medium. In our model, pathogens are grown on endotracheal tube segments in the presence of a novel synthetic ventilated airway mucus medium that simulates the in-host environment. Matrix-degrading enzymes and cryo-scanning electron microscopy were employed to characterize the system in terms of biofilm matrix composition and structure, as compared to standard laboratory growth medium. As seen in patients, the biofilms of ventilator-associated pneumonia pathogens in our model either required very high concentrations of antimicrobials for eradication or could not be eradicated. However, combining matrix-degrading enzymes with antimicrobials greatly improved the biofilm eradication of all pathogens. Our in vitro endotracheal tube model informs on fundamental microbiology in the ventilator-associated pneumonia context and has broad applicability as a screening platform for antibiofilm measures including the use of matrix-degrading enzymes as antimicrobial adjuvants.

show abstract

Epitopes in the capsular polysaccharide and the porin OmpK36 receptors are required for bacteriophage infection of Klebsiella pneumoniae

Cited by 9 publications

References 97 publications

The Effect of Lipopolysaccharides on the Electrostatic Properties of Gram‐Negative General Porins from Enterobacteriaceae

The Effect of Lipopolysaccharides on the Electrostatic Properties of Gram‐Negative General Porins from Enterobacteriaceae

A new model of endotracheal tube biofilm identifies combinations of matrix-degrading enzymes and antimicrobials able to eradicate biofilms of pathogens that cause ventilator-associated pneumonia

A new model of endotracheal tube biofilm identifies combinations of matrix-degrading enzymes and antimicrobials able to eradicate biofilms of pathogens that cause ventilator-associated pneumonia

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