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1 - 3 of 3 for "Sarah E. Maddocks"
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Manuka honey is bactericidal against Pseudomonas aeruginosa and results in differential expression of oprF and algD
The presence of Pseudomonas aeruginosa in cutaneous wounds is of clinical significance and can lead to persistent infections. Manuka honey has gained ground in clinical settings due to its effective therapeutic action and broad spectrum of antibacterial activity. In this study the effect of manuka honey on P. aeruginosa was investigated using MIC MBC growth kinetics confocal microscopy atomic force microscopy and real-time PCR. A bactericidal mode of action for manuka honey against P. aeruginosa was deduced (12 % w/v MIC; 16 % w/v MBC) and confirmed by confocal and atomic force microscopy which showed extensive cell lysis after 60 min exposure to inhibitory concentrations of manuka honey. The inability of honey-treated cells to form microcolonies was demonstrated and investigated using Q-PCR for three key microcolony-forming genes: algD lasR and oprF. The expression of algD increased 16-fold whereas oprF expression decreased 10-fold following honey treatment; lasR expression remained unaltered. These findings confirm that manuka honey is effective at inducing cell lysis and identify two targets at the genetic level that might be involved in this process.
Manuka honey inhibits the development of Streptococcus pyogenes biofilms and causes reduced expression of two fibronectin binding proteins
Streptococcus pyogenes (group A Streptococcus; GAS) is always of clinical significance in wounds where it can initiate infection destroy skin grafts and persist as a biofilm. Manuka honey has broad spectrum antimicrobial activity and its use in the clinical setting is beginning to gain acceptance with the continuing emergence of antibiotic resistance and the inadequacy of established systemic therapies; novel inhibitors may affect clinical practice. In this study the effect of manuka honey on S. pyogenes (M28) was investigated in vitro with planktonic and biofilm cultures using MIC MBC microscopy and aggregation efficiency. Bactericidal effects were found in both planktonic cultures and biofilms although higher concentrations of manuka honey were needed to inhibit biofilms. Abrogation of adherence and intercellular aggregation was observed. Manuka honey permeated 24 h established biofilms of S. pyogenes resulting in significant cell death and dissociation of cells from the biofilm. Sublethal concentrations of manuka honey effectively prevented the binding of S. pyogenes to the human tissue protein fibronectin but did not inhibit binding to fibrinogen. The observed inhibition of fibronectin binding was confirmed by a reduction in the expression of genes encoding two major fibronectin-binding streptococcal surface proteins Sof and SfbI. These findings indicate that manuka honey has potential in the topical treatment of wounds containing S. pyogenes.
Structure and function of the LysR-type transcriptional regulator (LTTR) family proteins
The LysR family of transcriptional regulators represents the most abundant type of transcriptional regulator in the prokaryotic kingdom. Members of this family have a conserved structure with an N-terminal DNA-binding helix–turn–helix motif and a C-terminal co-inducer-binding domain. Despite considerable conservation both structurally and functionally LysR-type transcriptional regulators (LTTRs) regulate a diverse set of genes including those involved in virulence metabolism quorum sensing and motility. Numerous structural and transcriptional studies of members of the LTTR family are helping to unravel a compelling paradigm that has evolved from the original observations and conclusions that were made about this family of transcriptional regulators.