Influence of MRSA biofilm phenotype on resistance to antimicrobial agents
Influence of MRSA biofilm phenotype on resistance to antimicrobial agents
A range of antibiotics with different modes of action were assessed for their ability to prevent biofilm formation and their activity against preformed immature and mature S. aureus biofilms. The ionophore antibiotics, which act against the plasma membrane, were the only group active against mature MRSA biofilms at the low concentrations of the planktonic MIC and ten times the MIC. In addition, synergistic effects were observed when ionophores were used in combination with antibiotics, including vancomycin.
Several promising novel chemistries were also identified with activity against mature S. aureus biofilm phenotype, even at low concentrations of ten times the planktonic MIC or less.
The QS signals PIA and AI-2 were investigated for their effects on biofilm formation and the biofilm phenotypic resistance. agr- mutants had increased biofilm formation compared to wild-type agr+ strains; however, no differences in antibiotic resistance of the two biofilms were seen. On the other hand, chemically synthesised AI-2, at high concentrations, caused a reduction in biofilm formation and had a synergistic effect on biofilm phenotypic resistance.
Nitric oxide (NO), an important eukaryotic signalling molecule, was recently found to cause the dispersal of P. aeruginosa biofilms. It also caused a reduction in biofilm formation by MRSA, and its addition in the mid concentration range caused increased susceptibility of the mature biofilm phenotype. It is possible that NO induces cells within the biofilm to revert to the susceptible planktonic phenotype, although the mechanism for this is currently unrecognised.
It is therefore concluded that the biofilm phenotype is an important contributor to the resistance of MRSA strains, and that it is possible to affect this resistance with signalling molecules. This work highlights the importance of screening new antimicrobial agents for activity against the biofilm phenotype.
University of Southampton
Caddy, Danielle Lynne
184595c0-cbf6-4669-9353-6006579c1340
2006
Caddy, Danielle Lynne
184595c0-cbf6-4669-9353-6006579c1340
Caddy, Danielle Lynne
(2006)
Influence of MRSA biofilm phenotype on resistance to antimicrobial agents.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
A range of antibiotics with different modes of action were assessed for their ability to prevent biofilm formation and their activity against preformed immature and mature S. aureus biofilms. The ionophore antibiotics, which act against the plasma membrane, were the only group active against mature MRSA biofilms at the low concentrations of the planktonic MIC and ten times the MIC. In addition, synergistic effects were observed when ionophores were used in combination with antibiotics, including vancomycin.
Several promising novel chemistries were also identified with activity against mature S. aureus biofilm phenotype, even at low concentrations of ten times the planktonic MIC or less.
The QS signals PIA and AI-2 were investigated for their effects on biofilm formation and the biofilm phenotypic resistance. agr- mutants had increased biofilm formation compared to wild-type agr+ strains; however, no differences in antibiotic resistance of the two biofilms were seen. On the other hand, chemically synthesised AI-2, at high concentrations, caused a reduction in biofilm formation and had a synergistic effect on biofilm phenotypic resistance.
Nitric oxide (NO), an important eukaryotic signalling molecule, was recently found to cause the dispersal of P. aeruginosa biofilms. It also caused a reduction in biofilm formation by MRSA, and its addition in the mid concentration range caused increased susceptibility of the mature biofilm phenotype. It is possible that NO induces cells within the biofilm to revert to the susceptible planktonic phenotype, although the mechanism for this is currently unrecognised.
It is therefore concluded that the biofilm phenotype is an important contributor to the resistance of MRSA strains, and that it is possible to affect this resistance with signalling molecules. This work highlights the importance of screening new antimicrobial agents for activity against the biofilm phenotype.
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Published date: 2006
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Local EPrints ID: 466032
URI: http://eprints.soton.ac.uk/id/eprint/466032
PURE UUID: ce1baa66-810f-4084-beae-842efcac5446
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Date deposited: 05 Jul 2022 04:03
Last modified: 16 Mar 2024 20:29
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Author:
Danielle Lynne Caddy
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