Award details

Assessment of the relative ability of novel peptide biocides to prevent the development of microbial resistance and to disrupt biofilm.

Reference	BB/G01695X/1
Principal Investigator / Supervisor	Professor Curtis Dobson
Co-Investigators / Co-Supervisors	Dr Bridie Kelly, Professor Andrew McBain
Institution	The University of Manchester
Department	Life Sciences
Funding type	Skills
Value (£)	74,410
Status	Completed
Type	Training Grants
Start date	01/10/2009
End date	30/09/2013
Duration	48 months

Abstract

unavailable

Summary

The project will focus on two key areas: (i) resistance and (ii) biofilm disruption. All techniques are currently in use in Dr McBain's or Dr Dobson's laboratories. The initial focus will be to examine several Ai2 peptides with strongest activity against key organisms relevant to medical devices, alongside existing cationic (or other) biocides, including PHMB, chlorhexidine, triclosan and silver. In addition Ai2's large peptide library will also be made available to the project. The student will spend 6-9 months of the project seconded to Ai2, allowing selection and assessment of series of peptides with systematic sequence modification to be assessed, allowing structure activity relationships to be established. (i) Resistance. In years 1 and 2, the potential of compounds to generate resistance against a panel of around 30 microorganisms will be tested using established methodology (1-2). Plates containing a biocide concentration gradient will be incubated appropriately for up to 4 days. Microbial growth observed near to the endpoint in the transition between the growth and growth-inhibition area will be transferred to another gradient plate prepared in the same way. This process will be repeated until 14 passages have been completed. Unexposed microbes and those harvested after 7 and 14 biocide passages will be subjected to minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) testing. The MBCs will be determined using MIC plates, with aliquots being spot plated onto appropriate agar and incubated overnight. The MBC will be expressed as the lowest concentration of biocide at which growth was not observed after 5 days' incubation. Appropriate antibiotics will be used as positive controls. For any biocide found to generate resistance the possibility that cross-resistance might be generated will be examined alongside apoE-peptides (as negative controls). Strains showing resistance will be exposed to other biocides and the MICs / MBCs measured. (ii) Biofilm. As well as the above experiments examining planktonic microbes, in years 2-4 the efficacy of the peptides against biofilms will be tested in comparison with other commonly used biocides using the Calgary Biofilm Device (CBD) (3). In brief the CBD consists of 96 wells in which 96 pegs attached to the lid are immersed. The biofilm is formed by inoculating medium in the device and incubating it under appropriate conditions with rocking. Once the biofilm has been established the peg section will be transferred to a standard 96 well plate containing dilutions of the peptides / biocides. After a suitable incubation period the viability of the biofilm will be determined. Biofilms formed by key wound-associated species including Pseudomonas aeruginosa and Staphylococcus aureus will be tested. For peptides showing efficacy comparing well to that for other biocides, further more detailed assessment of activity against biofilms will be tested using various continuous culture biofilm models, using relevant biomaterials as substrata. Thus, we will uncover both the comparative performance of apoE-derived peptides relative to other biocides in these two areas, and furthermore (in section (ii)) uncover potential structure-activity relationships within the apoE-peptide family. Activities for peptides groups containing a range of natural and non-natural substitutions will be obtained. For example, series of peptides based around the core apoEdpL-W sequence (WRKWRKRWWWRKWRKRWW), in which systematic modification of either the hydrophobic cationic groups will be tested, and properties associated with specific sequence characteristics identified. 1. Ledder R.G., Gilbert P., Willis C., McBain A.J. (2006) Journal of applied microbiology, 100, 1132-1140. 2. McBain A.J., Ledder R.G., Sreenivasan P., Gilbert P. (2004) Journal of antimicrobial chemotherapy, 53, 772-777. 3. Ceri H., Olson M.E., et al. (1999) Journal of clinical microbiology, 37, 1771-1776

Committee	Not funded via Committee
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	Training Grant - Industrial Case

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search