Dr Samantha McLean is a senior lecturer in microbiology. She is a member of the Antimicrobial Resistance, Omics and Microbiota (AROM) research theme, microbiology lead for the Medical Technologies Innovation Facility (MTIF) and is actively engaged in antimicrobial and biofilm research.
She is a module leader in both undergraduate and postgraduate Molecular Microbiology modules. Dr McLean is a Masters and Undergraduate degree research project supervisor and currently teaches on the following modules:
- Introduction to Microbiology
- Molecular Microbiology (UG and PG)
Dr McLean received a BSc (Hons) degree in Microbiology at the University of Leeds before moving to the University of Sheffield where she completed her PhD in the department of Molecular Biology and Biotechnology. She spent a further six years at the University of Sheffield as a Research Associate investigating the interaction of enterobacteria with small molecules of the innate immune response, including reactive oxygen species, reactive nitrogen species and carbon monoxide.
Dr McLean went on to spend two years at the University of Nottingham as a Research Fellow researching the optimisation of industrial gas fermentation for commercial low-carbon fuel and chemical production through systems and synthetic biology approaches.
In February 2016 Dr McLean took up the position of Lecturer in Microbiology at Nottingham Trent University.
Dr McLean is a member of the Antimicrobial Resistance, Omics & Microbiota research group, situated within the Centre for Health, Ageing and Understanding Disease (CHAUD). Her research interests include investigating the microbial colonisation of medical device materials and the efficacy of novel approaches to prevent colonisation. She also has a wider interest in the characterisation of novel antimicrobial compounds.
The McLean group is part of the School of Science and Technology, within our rapidly evolving Clifton Campus, a multi-award-winning site with state of the art bioscience research and teaching labs. Campus is also home to the Medical Technologies Innovation Facility, a research and development facility available to industry and academic institutions to support and accelerate the development of innovative medical technologies.
Overarching research theme
The overuse and misuse of antibiotics in health care, agriculture and industry is pushing us towards a post antibiotic era. The rate at which antimicrobial resistance (AMR) is rising is vastly greater than the development of new antibiotics. Resistant strains are increasingly seen within the community where previously they were restricted to the hospital setting. Alongside this, resistance to last line antibiotics such as colistin is now more frequently observed. With yearly death rates attributed to AMR predicated to reach 10 million by 2050 it is vital that novel antimicrobial options are explored. Our research is focussed, via several projects, upon better understanding the activity of antimicrobial compounds and surfaces, so that we may drive the development of new antimicrobial products that will reduce the incidence and severity of infection.
Metals as antimicrobials
Metal-based compounds, including silver, copper and ruthenium, offer potential as a antimicrobials. Silver has demonstrated antimicrobial application in numerous research studies and has been used widely as an antimicrobial throughout history. Today, silver salts are used in materials from advanced wound dressings to lunch boxes. Ruthenium-containing compounds have been less well studied but offer significant potential as a novel antimicrobials.
Our research group explores the antimicrobial action of metal-containing compounds to understand the mechanisms of action. We utilise a variety of antimicrobial efficacy assays, ranging from simple testing methods for rapid screening to in-depth analysis of antimicrobial activity and toxicity of compounds to moth larvae and human cell lines. Alongside this, transcriptomic analysis is undertaken using cutting-edge RNASeq technologies that allows us to understand how bacteria sense and respond to the threat of these novel antimicrobials.
Microbial colonisation of medical device materials (biofilms)
Microbial contamination caused by biofilms is a major global challenge, costing $4tn per annum across all industries, exerting economic, social, and environmental impact. Global business spends considerable resources on microbial contamination prevention and eradication technologies. Bacteria colonise surfaces by aggregating to form biofilms, which makes them resistant to antimicrobials and extremely difficult to remove. Bacterial infections caused by colonisation of implanted medical devices act as a driver of serious infections and current strategies to control them are limited to debridement, device removal and aggressive antibiotic treatment. Therefore, it is critical that medical device materials be developed with antibiofilm properties to reduce the incidence and severity of infections.
Our research here investigates ways to prevent and/or manage biofilm colonisation of innate surfaces on medical devices. We are developing models of biofilm formation in a variety of clinically relevant conditions, including in CDC Bioreactors, Drip Flow Reactors and Modified Robbins Devices, to screen the efficacy of new antimicrobial medical device materials in a manner that has real-world relevance and supports product development. We also aim to drive antimicrobial medical device development with industry and multi-disciplinary academic partners to translate our research into real-world impact.
Commercialisation of new materials that prevent microbial contamination need to demonstrate safety and effectiveness. However, within the UK there is a lack of standards that can be used to support product claims – such as “prevents biofilm formation”. This means that tests that are used are often inadequate for real world scenarios and lead to high failure rates as well as lengthy and costly regulatory claim processes. Industry consultation consistently provides the same messages: that the lack of biofilm standards is holding back industry innovation and leads to a failure to address these major challenges. Indeed, the UK government recognise the importance of standards stating that standards, measurement, and accredited conformity assessment play a critical role in supporting innovation and will enable its swift and safe commercialisation.
Therefore, it is not enough to only develop new antimicrobial materials, we must also invest time into the development of standard methodologies if we are to move the industry forward and break down these barriers to innovation. Dr McLean is a member of the British Standards Institute CH/216/0-/03 panel on products and biofilms that are investigating the development of new BSI biofilm standards.
Working in the McLean group
Opportunities arise to carry out postgraduate research towards a PhD in the areas identified above. Further information may be obtained on the NTU Research Degrees website.
Dr McLean is a STEM Ambassador, regularly undertaking outreach projects to develop microbiology literacy and to promote women and girls in STEM.
Sponsors and collaborators
The McLean group collaborate with a number of academic and industry partners:
Research in the McLean group is supported by the Nottingham Trent University PhD studentship scheme, the School of Science and Technology MTIF Fellowship Programme, Innovate UK, the National Biofilms Innovation Centre, the African Research Excellence Fund and the National Institute for Health and Care Research.
Mannix-Fisher, E., and McLean, S., (2021) The antimicrobial activity of silver acetate against Acinetobacter baumannii in a Galleria mellonella infection model. PeerJ 9:e11196 DOI 10.7717/peerj.11196
Varney, A.M., Smitten, K.l., Thomas J.A., and McLean, S. (2020) Transcriptomic Analysis of the Activity and Mechanism of Action of a Ruthenium(II)-Based Antimicrobial That Induces Minimal Evolution of Pathogen Resistance. ACS Pharmacology & Translational Science DOI: 10.1021/acsptsci.0c00159
Wareham, L.K., McLean, S., Begg, R., Rana, N., Ali, S., Kendall, J.J., Sanguinetti, G., Mann, B.E., and Poole, R.K. (2018) The Broad-Spectrum Antimicrobial Potential of [Mn(CO)4(S2CNMe(CH2CO2H))], a Water-Soluble CO-Releasing Molecule (CORM-401): Intracellular Accumulation, Transcriptomic and Statistical Analyses, and Membrane Polarization.Antioxidants and Redox Signalling 28(14), 1286-1308
Wareham, L.K., Begg, R., Jesse, H.E., Beilen, J.V., Ali, S., Svistunenko, D., McLean, S., Hellingwerf, K., Sanguinetti, G., and Poole, R.K. (2016) Carbon monoxide gas is not inert, but global, in its consequences for bacterial gene expression, iron acquisition and antibiotic resistance. Antioxidants and Redox Signalling 24 (17), 1013-1028
Humphreys, C.M., McLean, S., et al (2015) Whole genome sequence and manual annotation of Clostridium autoethanogenum, an industrially relevant bacterium. BMC Genomics 16, 1085
Wilson, J.L., McLean, S., Begg, R., Sanguinetti, G., and Poole, R.K. (2015) Analysis of transcript changes in a heme-deficient mutant of Escherichia coli in response to CORM-3 [Ru(CO)3Cl(glycinate)]. Genomics Data 5, 231-234
Wilson, J.L., Wareham, L., McLean, S., Begg, R., Greaves, S., Mann, B.E., Sanguinetti, G., and Poole, R.K. (2015) CO-releasing molecules have non-heme targets in bacteria: transcriptomic, mathematical modelling and biochemical analyses of CORM-3 [Ru(CO)3Cl(glycinate)] actions on a heme-deficient mutant of Escherichia coli. Antioxidants and Redox Signalling 23, 148-162
*Rana, N., *McLean, S., Mann, B.E., and Poole, R.K. (2014) Interaction of the carbon monoxide-releasing molecule Ru(CO)3CL(glycinate) (CORM-3) with Salmonella enterica serovar Typhimurium: in situ measurements of CO binding by integrating cavity dual beam spectrophotometry. Microbiology 160, 2771-2779
Balodite, E., Strazdina, I., Galinina, N., McLean, S., Rutkis, R., Poole R.K., and Kalnenieks, U. (2014) Structure of Zymomonas mobilis respiratory chain: oxygen affinity of electron transport and the function of cytochrome c peroxidase. Microbiology 160, 2045-2052
Nagel, C., McLean, S., Poole, R.K., Braunschweig, H., Kramer, T., and Schatzschneider, U. (2014) Introducing [Mn(CO)3(tpa-κ3N)]+ as a novel photoactivatable CO-releasing molecule with well-defined iCORM intermediates - synthesis, spectroscopy, and antibacterial activity. Dalton Transactions 43, 9986-9997