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Dr Susannah Walsh

Job: Associate Head, School of Pharmacy; Associate Professor in Microbiology

Faculty: Health and Life Sciences

School/department: Leicester School of Pharmacy

Address: De 91影视 University, The Gateway, Leicester, LE1 9BH.

T: +44 (0)116 257 7971

E: swalsh@dmu.ac.uk

W: /pharmacy

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Personal profile

Dr Susannah Walsh's research interests include all of the following:

  • Disinfection
  • Sterilisation
  • Infection control
  • Antimicrobials
  • Biocides
  • Hydrogen peroxide
  • Whole body washing
  • Pre-operative solutions
  • Ortho-phthalaldehyde
  • Chlorhexidine
  • Antimicrobial fabrics
  • Antimicrobial catalyst
  • Novel heterogeneous catalyst.

Research group affiliations

Leciester Institute for Pharmaceutical Innovation

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Infectious Disease Research Group

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Publications and outputs


  • dc.title: Priming with biocides: A pathway to antibiotic resistance? dc.contributor.author: Adkin, Pat; Hitchcock, Andrew; Smith, Laura J.; Walsh, Susannah E. dc.description.abstract: To investigate the priming effects of sub-inhibitory concentrations of biocides on antibiotic resistance in bacteria. Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were exposed to sub-inhibitory concentrations of biocides via a gradient plate method. Minimum inhibitory concentration (MIC) and antibiotic susceptibility were determined, and efflux pump inhibitors (thioridazine and chlorpromazine) were used to investigate antibiotic resistance mechanism(s). Escherichia coli displayed a twofold increase in MIC (32-64鈥塵g鈥塴 ) to H O which was stable after 15 passages, but lost after 6鈥墂eeks, and P. aeruginosa displayed a twofold increase in MIC (64-128鈥塵g鈥塴 ) to BZK which was also stable for 15 passages. There were no other tolerances observed to biocides in E. coli, P. aeruginosa or S. aureus; however, stable cross-resistance to antibiotics was observed in the absence of a stable increased tolerance to biocides. Sixfold increases in MIC to cephalothin and fourfold to ceftriaxone and ampicillin were observed in hydrogen peroxide primed E. coli. Chlorhexidine primed S. aureus showed a fourfold increase in MIC to oxacillin, and glutaraldehyde-primed P. aeruginosa showed fourfold (sulphatriad) and eightfold (ciprofloxacin) increases in MIC. Thioridazine increased the susceptibility of E. coli to cephalothin and cefoxitin by fourfold and twofold, respectively, and both thioridazine and chlorpromazine increased the susceptibility S. aureus to oxacillin by eightfold and fourfold, respectively. These findings demonstrate that sub-inhibitory concentrations of biocides can prime bacteria to become resistant to antibiotics even in the absence of stable biocide tolerance and suggests activation of efflux mechanisms may be a contributory factor. This study demonstrates the effects of low-level exposure of biocides (priming) on antibiotic resistance even in the absence of obvious increased biocidal tolerance. dc.description: open access article

  • dc.title: Sterilization in Practice dc.contributor.author: Walsh, Susannah E.; Maillard, J-Y.

  • dc.title: Principles of Sterilization dc.contributor.author: Walsh, Susannah E.; Maillard, J-Y.

  • dc.title: Pyrogallol is the main antibacterial compound in the aqueous extract of Boswellia dalzielii bark dc.contributor.author: Alfa, Hajara; Arroo, R. R. J.; Walsh, Susannah E.; Ruparelia, K. C.; Bhambra, Avninder S.; Slater, A. dc.description.abstract: Plants belonging to the genus Boswellia (Burseraceae) have long been appreciated for their pharmacological properties such as anti-inflammatory, antioxidative and anticancer activities1. In the Northern part of Nigeria, the bark of B. dalzielii Hutch. is an important ingredient for the treatment of infections2. To identify water-soluble antibacterial compounds, powdered bark was macerated in water for 6 to 24h at a range of temperatures. The aqueous extracts were subsequently fractionated by column chromatography, and the fractions were initially screened against wild type and methicillin resistant strains of Staphylococcus aureus. Then, minimum inhibitory concentrations of purified fractions were determined using series of concentrations from 2 mg/mL to 8 渭g/mL. Results showed that longer maceration resulted in stronger antibacterial activity. With the aid of NMR and accurate mass analysis, pyrogallol was identified as the main antibacterial agent, with MIC values ranging from 24-28 渭g/mL for MRSA to 34-36 渭g/mL for wild-type S. aureus. Gallic acid was found to play a lesser role (MIC >200 渭g/mL). Pyrogallol was found not to be a plant secondary metabolite, but a metabolic product from microbial degradation of gallic acid from the bark. Only two bacterial species could be isolated from the plant material, which were identified as Raoultella planticola and Enterobacter cloacae. Of these two micro-organisms, R. planticola was shown to be responsible for the production of pyrogallol. This is an example of bacterial allelopathy, which results in an increased efficacy of the aqueous extract.

  • dc.title: Presence of antibiotic-resistant bacteria in faecal samples collected in urban parks in Leicester, UK. dc.contributor.author: Baho, S.; Hoosen, H.; Samarasinghe, S.; Walsh, Susannah E.; Lobo-Bedmar, M. C.; del Aguila, C.; Fenoy, S.; Izquierdo, F.; Magnet, A.; Pena-Fernandez, A. dc.description.abstract: Although a public health concern, there is limited information about the presence of antibiotic-resistant human pathogenic bacteria in the UK environment. Identification of environmental contaminants, including biological hazards, is critical to protect the public health. Klebsiella pneumoniae and Escherichia coli are considered important Gram-negative opportunistic pathogens. Urban animals may play a significant zoonotic role in the dispersion of these pathogens. 46 faecal samples were collected in different public parks in Leicester city in April-May 2016. Samples were collected in days of no rain to avoid problems with the integrity of the sample. Animal species were identified by a veterinarian: 18 avian (5 pigeons, 13 waterfowls), 15 dog, 3 cat, 7 fox and 3 unidentified. Faecal samples were analysed using routine coprological methods of modified Telemann and MIF. Seven Extended-Spectrum -Lactamases genes for Gram-negative bacteria, and bacteria species (K. pneumoniae and E. coli) were determined using specific primers by PCR. DNA was extracted by bead disruption of prepared samples using the Fast-DNA-Spin kit, according to the manufacturer鈥檚 instructions. We detected genes for enzymes for those -Lactamases in 11 samples (specifically CTX-M-15), which corresponded with 6 samples form waterfowls, 3 from dogs and 2 from foxes. None of the samples was identified for K. pneumoniae or E. coli. Although the results are preliminary, the data obtained in this study has revealed the presence of antibiotic resistant bacteria in urban areas that are highly frequented by citizens, which may require recovery and restoration in addition to pro-active public health measures to protect public health.

  • dc.title: New platforms for multi-functional ocular lenses: engineering double-sided functionalized nano-coatings dc.contributor.author: Mehta, P.; Justo, L.; Walsh, Susannah E.; Arshad, M. S.; Wilson, C. G.; O'Sullivan, C. K.; Moghimi, S. M.; Vizirianakis, I. S.; Avgoustakis, K.; Fatouros, D. G.; Ahmad, Z.

  • dc.title: Microneedle Coating Techniques for Transdermal Drug Delivery. dc.contributor.author: Haj-Ahmad, R.; Khan, H.; Arshad, M. S.; Rasekh, M.; Hussain, A.; Walsh, Susannah E.; Li, X.; Chang, M-W.; Ahmad, Z.

  • dc.title: Filtration Sterilization dc.contributor.author: Walsh, Susannah E.; Denyer, S. P.

  • dc.title: The development of sol-gel based hybrid polymers to achieve multifunctional textile fabric surface coating dc.contributor.author: Shen, Jinsong; Smith, Edward; Chizyuka, M.; Walsh, Susannah E.; Martinkov谩, L.

  • dc.title: Mycobactericidal and bactericidal properties of a novel antimicrobial catalyst and its 鈥榣eachate鈥� dc.contributor.author: Price, S. L.; Shen, Jinsong; Huddersman, Katherine; Walsh, Susannah E.

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Research interests/expertise

Infection prevention and control and includes:

Activity and mode of action of disinfectants and sterilants: involvement in the assessment of the activity and mode of action of a new high level disinfectants. I have been responsible for leading the microbiology aspects of randomised controlled trials (for example, the use of brushes and picks in surgical scrubbing and the efficacy of body washing). I have also conducted studies investigating the possible link between biocide use and antibiotic resistance.

Development of novel antimicrobials/ disinfectants: I have collaborated with Prof Huddersman (De 91影视 University) to develop a novel antimicrobial catalyst which has been patented; and with other colleagues to test novel compounds and natural products for antibacterial activity.

Efficacy of travel hand rubs: I have worked with Prof L Goodyer to investigate the antiviral activity of commercially available travel hand rubs and develop more effective formulations.

Evaluation of test methods for antimicrobial fabrics: Collaborations with the textile research group (TEAM) in the Faculty of Art and Design, have focused on the antimicrobial efficacy of fabrics.

Areas of teaching

  • Microbiology
  • Sterile Products

Qualifications

BSc, PhD, MBA

Courses taught

  • Pharmacy (MPharm)
  • Pharmaceutical and Cosmetics Science (BSc)
  • Forensic Science (BSc)

Membership of external committees

MHRA, Commission of human medicine, chemistry, pharmacy and standards, expert advisory group 2020 to current

Pharmacy Schools Council, Deputy Chair, Admissions Group 2017 to current

Deputy 91影视 representative at the Pharmacy Schools Council 2017 to current

Medilink East Midlands, Infectious Diseases Special Interest Group committee member  2017 to current

Main committee member of the Society for Applied Microbiology 2004-2007

Convenor and Chair of the infection prevention and treatment subcommittee of the Society for Applied Microbiology 2002-2004

Convenor and Chair of the membership subcommittee of the Society for Applied Microbiology 2004 - 2009

Convenor and Chair of the industrial microbiology subcommittee of the Society for Applied Microbiology 2010 - 2009

Member of the meetings subcommittee of the Society for Applied Microbiology 2002 - 2009

Member of the communications subcommittee of the Society for Applied Microbiology 2006 - 2009

Membership of professional associations and societies

  • Member of the Society for Applied Microbiology since 1996
  • Member of the Society for General Microbiology since 2002
  • Member of the Hospital Infection Society since 1999
  • Member of the American Society for Microbiology since 1999.

Conference attendance

  1. Pankhania, B., Huddersman, K., Walsh S.E. Modelling disinfection of biological threats using Bacillus thuringiensis spores: Efficacy of hydrogen peroxide, heterogeneous catalysis and germinant combinations Chemical and Biological Terrorism Defense, Gordon Research Conference: Detection, Countermeasures and Prevention of Chemical and Biological Threats. 3-8 March 2019, Ventura, California, USA (oral presentation).
  2. Walsh, S. Rapid Fire Talk (oral presentation) Preventing infections using De 91影视 University’s novel catalyst technology. ASM Microbe 2017, 3 June, New Orleans, USA.
  3. Walsh, S. Preventing infections: is 91影视's catalyst system the answer? Invited speaker, TRIIFIC! Healthcare Textiles. Medilink East Midlands, Leicester, 2 November 2016.
  4. Walsh, S. Pankhania, B, Sewell, S., Laird, K, Smith, L., Huddersman, K. Preventing infections using De 91影视 University’s novel catalyst technology. ASM Microbe 2017, 1-5 June, New Orleans, USA.
  5. Walsh, S. Enhancing disinfections: is 91影视’s catalyst system the answer? Invited speaker, C&C Europe Crops and Chemicals: R&D of disinfectants, detergents & cleaning products. Berlin, Germany, 10-11 February, 2015.
  6. Shen, J., Smith, E., Chizyuka, M., Walsh, S. and Martinková, L. (2013) The development of sol-gel based hybrid polymers to achieve multifunctional textile fabric surface coating. XVII Int Sol-Gel conference, Madrid, Spain, 25-30 Aug
  7. Shen, J., Smith, E., Chizyuka, M., Walsh, S. and Martinková, L. (2013) Sol-gel process of cotton fabric to achieve multifunctionality. 13th AUTEX World Textile Conf, Dresden, Germany, 22-24 May
  8. Shen, J., Smith, E., Chizyuka, M., Walsh, S. and Martinková, L. (2012) Nanolayer surface coating of cotton fabric with sol-gel based hybrid polymers to achieve hydrophobic and antibacterial properties. 12th World Textile Conf AUTEX, 13-15 June, Zadar, Croatia
  9. Shen J, Smith E, Chizyuka M, Walsh S, Martinková L Sol gel hybrid polymer coating of cotton fabrics. Presented at the International Conference on Eco-Dyeing/Finishing and Green Chemistry in Hangzhou, China 2011.
  10. Price S, Shen J, Huddersman K, Walsh S. Mycobactericidal and bactericidal properties of a novel antimicrobial catalyst and it’s leachate. Poster presented at the Society for Applied Microbiology Summer Conference in Dublin July 2011. 
  11. Walsh S, Boateng K, Price S, Huddersman K Potentiation of hydrogen peroxide activity using a novel heterogeneous catalyst. Poster presented at the American Society for Microbiology General Meeting in New Orleans May 2011.
  12. Jenkins P, Walsh S, Gould D, Hilliam R, Goodyer L, Tanner J, Efficacy of whole body wash and hand rub formulations. Poster presented at the American Society for Microbiology General Meeting in New Orleans May 2011.
  13. Tanner J, Gould D, Jenkins P, Hilliam R, Mistry N, Walsh S E, Whole body washing to reduce bacteria on skin: a randomised trial. Poster presented at the 7th International Conference of the Hospital Infection Society. Liverpool October 2010.
  14. Price S, Boateng K, Shen J, Huddersman K, Walsh S. Investigating the antibacterial properties of a novel heterogeneous PAN catalyst. Poster presented at the Society for Applied Microbiology Summer Conference in Brighton July 2010.
  15. Walsh S E, Davies M, Patel K, Yasmin Y, Goodyer L. Bactericidal activity of H20-NO hand rub formulations against Escherichia coli. Poster presented at the 11th Conference of the International Society of Travel Medicine. Budapest, Hungary May 2009.
  16. Walsh S E Invited speaker at the Society for Applied Microbiology Summer Conference (Edinburgh 2008). Presentation title: Careers in Academia.

Consultancy work

Microbiology, specialising in disinfection and sterilisation.

Current research students

  • I currently have 7 PhD students (4 as first supervisor) and have 5 successful completions (4 PhD, 1 MRes), with a pipeline of 4 additional completions expected in 2020.

Externally funded research grants information

    1. PAL International 2020, PeroxyCat – proof of principle, matched funding for HEIF £12,500.
    2. Better Vision Solutions 2019 Milestone Payment £10,000. Licensee payment to 91影视.
    3. DSTL 2017 £70,000. DSTL - Sporicidal disinfection using 91影视's novel catalyst technology. PI (CI K. Huddersman). Email confirmation of funding success has been received, funding is subject to contract.
    4. DEB 2015 £4,960. DEB: assessment of the antimicrobial efficacy of the 91影视 catalyst.
    5. Better Vision Solutions 2015 Milestone Payment £30,000. Licensee payment (third party test results and due diligence investigation results).
    6. Better Vision Solutions 2015 Milestone Payment £15,000. Licensee payment (access fee)
    7. Better Vision Solutions Consultancy 2015 $4500 (£3,130) via DMEL. Consultancy focused on commercialisation of our novel catalyst system with our Licensee BVS.
    8. Reckitt Benckiser 2014 DMEL commercial testing £14,650, antimicrobial screening of the novel catalyst system. Project complete
    9. Society for Applied Microbiology Students into Work Grant £2,500 entitled ‘antimicrobial catalyst’ (2014). Project complete.
    10. Molnlycke Health Care £585.88 ‘Source Control’ meeting honorarium for acting as expert microbiologist, Jan 2012.
    11. Molnlycke Health Care £25K ‘pre-operative solutions: a randomised controlled trial’. Principal investigator Prof Judith Tanner, Dr S Walsh responsible for microbiology aspects of the proposal/ trial design and line management of the microbiology research associate. (2011).
    12. Society for Applied Microbiology Students into Work Grant £2,100 entitled ‘effect of ventilation method on microbial air quality’ (2011). 
    13. International PhD Programme (Ms N Sonji). Project investigating ‘antibacterial metal complexes’ in conjunction with the Lebanese International University, Beirut. Student is now commencing studies and we have received their registration form. 
    14. Molnlycke Heath Care £918 commercial work examining the residual effect of surgical scrubbing on Escherichia coli. 
    15. Molnlycke Heath Care £1,100 commercial work examining the residual effect of chlorhexidine hand washes and rubs on Escherichia coli. 
    16. Framework 7 SAFEPROTEX work package £45K: led by Dr Jinsong Shen (principle investigator). Dr S Walsh is responsible for management of the microbiology aspects of this project and is second PhD supervisor. 
    17. Molnlycke Heath Care £25K ‘whole body washing randomised controlled trial on healthy volunteers’, March-May 2010. Principal investigator Prof Judith Tanner, Dr S Walsh responsible for microbiology aspects of the proposal/trial design and line management of the microbiology research associate. This pilot study is intended to lead to a larger study looking at the effect of body washing on hospital inpatients. 
    18. Hospital Infection Society Small Research Grant £5K awarded to Prof J Tanner. Nail brushes and nail picks during the surgical scrub to reduce bacteria on hands: a randomised controlled trial. Microbiology aspects led and designed by Dr S Walsh, 2008-9. 
    19. Hospital Infection Society Small Research Grant for £5K entitled ‘Biocidal activity and resistance and effects on antibiotic susceptibility’, 2002-current. This study aims to improve the understanding of biocides and their effect on antibiotic susceptibility. This grant is for the purchase of equipment and consumables to support this project. 
    20. Society for Applied Microbiology Students into Work Grant for £2,100 entitled ‘Efficacy of hand rubs for use in travel medicine’, 2008 (July to September). 
    21. Society for Applied Microbiology Students into Work Grant for £2,100 to investigate ‘test methodology and activity of antimicrobial fabrics’, 2006 (July to September).

Internally funded research project information

    1. HEIF 2020, PeroxyCat – proof of principle. £12,500 plus matched external funding.
    2. Understanding bacterial resistance and dissemination: the impact of biocides and preservatives. Graduate School Full bursary PhD Scholarship. 2016-2019. 
    3. Investigation into evaporative coolers for controlling legionella bacteria using innovative catalyst technology. HEIF proof of principle. Nov 2015-April 2016. 
    4. Molecular characterization and identification of emerging parasitic pathogens in the environment in the Midlands, UK: public health implications. RCIF2 2015-2016. £21,767. 
    5. Prevention of waterborne disease using 91影视’s patented catalyst technology. 91影视 fees-only Scholarship for Bhishak Pankhania 2015-2021 (part time). 
    1. Internally allocated doctoral training grant (fees only studentship Mr K. Omoniala) ‘modified titanium as an antibacterial biomaterial’. 
    2. HEIF 4 pump priming £9,300 awarded to Dr S. Walsh and Dr K. Laird to purchase a MAS-100 Microbial air monitoring system and obtain a Hazard Analysis and Critical Control Point (HACCP) level 4 qualification.
    3. Internally allocated doctoral training grant entitled ‘Development of a broad spectrum, sporicidal, cost saving disinfectant incorporating a novel antimicrobial catalyst’, 2009-12. 
    4. Internally allocated doctoral training grant entitled “Novel polymer supported catalyst for biocidal applications”, 2005-8.
    5. Hydrogen peroxide is activated by the catalyst with resultant biocidal activity allowing lower hydrogen peroxide dosing. This award supported a PhD student who has now successfully completed.

Published patents

Huddersman K. D., Walsh S. Antimicrobial Catalyst, US Patent 8513303 issued on August 20th 2013. Inventor.

Huddersman K. D., Walsh S. Antimicrobial Catalyst, PCT Patent Application No. PCT/GB2008/002864. Published on 05 Mar 2009 under No. WO 2009/027649. European patent application No 08788424.3. Inventor.

Other relevant patent numbers for the Antimicrobial Catalyst:
1499358 FR 10/01/1967, 2346569 GB 08/01/2000, WO 01/81671 WO 11/01/2001, WO 2005/073289 WO 08/01/2005, WO 2007/099293 WO 09/01/2007

Professional esteem indicators

MHRA, Commission of human medicine, chemistry, pharmacy and standards, expert advisory group  2020 to current

Pharmacy Schools Council, Deputy Chair, Admissions Group 2017 to current

Deputy 91影视 representative at the Pharmacy Schools Council 2017 to current

Medilink East Midlands, Infectious Diseases Special Interest Group committee member 2017 to current

Editor for the Journal of Applied Microbiology and Letters in Applied Microbiology 2004-2007.

Susannah Walsh