Bioscience for an integrated understanding of health

Category: Standard Studentships

Novel approaches in drug targeting and delivery to combat Gram-negative bacterial pathogens

Project No. 2463


Primary Supervisor

Dr Mark Shepherd – University of Kent


Dr Nicholas Evans – University of Southampton


A major problem with drug development is that active compounds are not always delivered to the requisite site.

Rationale: A major problem with drug development is that active compounds are not always delivered to the requisite site. This project seeks to span the disciplines of microbiology and bioengineering to develop new technologies to target Gram-negative bacterial pathogens, one of the most serious health threats of our time.
Preliminary work in the Shepherd lab has identified a class of steroid drugs that inhibit cytochrome bd, an emerging drug target, from E. coli and Staphylococcus aureus (Henry et al. 2023), and has very recently cloned and expressed recombinant cytochrome bd complexes from a variety of Gram-negative pathogens (e.g. Burkholderia cenocepacia, Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumanii). The Evans lab has extensive expertise in a range of drug formulation techniques, recently including the use of polymersomes to deliver antimicrobials to host macrophages to kill intracellular bacteria (Porges et al. 2021).

Approaches and preliminary work: The student will quantify the efficacy of steroid drugs against cytochrome bd from a range of Gram-negative pathogens using oxygen electrode measurements, viability assays, and will trial a novel high-throughput fluorescence technique to measure oxygen consumption that has been recently developed in the host lab. Novel nanoencapsulation techniques will be developed to optimise steroid drug loading and access to the aforementioned bacterial pathogens that have been internalised by immune cells.

Potential Impact: This work will develop cutting edge research technologies that could be relevant to a number of different antimicrobial classes, and could change the way that drug susceptibility work is undertaken with immune cells and intracellular pathogens.

Candidate qualities: Academic background in molecular biosciences is essential. Practical experience with microbiology and knowledge of biotechnology and/or bioengineering is desirable.

Publications and relevant techniques:

Henry, S.A., Webster C.M., Shaw, L.N. Torres, J.T., Jobson, M.E., Totzke, B.C., Jackson, J.J., McGreig, J.E., Wass, M.N., Robinson, G.K., Shepherd, M. (2023) FDA-approved steroid drugs inhibit bacterial respiratory oxidases and are lethal towards methicillin-resistant Staphylococcus aureus. Under review. (In silico approaches to drug discovery, dose response assays with steroid drugs, spectroscopic quantitation of respiratory complex assembly in whole cells).

Porges, E., Jenner, D., Taylor, A. W., Harrison, J. S. P., De Grazia, A., Hailes, A. R., Wright, K. M., Whelan, A. O., Norville, I. H., Prior, J. L., Mahajan, S., Rowland, C. A., Newman, T. A., and Evans, N. D. (2021). Antibiotic-loaded polymersomes for clearance of Burkholderia thailandensis. ACS Nano, 15(12), 19284-19297. (Encapsulation of drugs for delivery to macrophages to target a Gram-negative bacterial pathogen).

Ribeiro CA, Rahman LA, Holmes LG, et al (2021) Nitric oxide (NO) elicits aminoglycoside tolerance in Escherichia coli but antibiotic resistance gene carriage and NO sensitivity have not co-evolved. Arch Microbiol 203:2541–2550. (Antimicrobial susceptibility testing, genomic analysis of clinical isolates).

Webster, C.M., Woody, A.M., Fusseini, S., Holmes, L.G., Robinson, G.K., and Shepherd. M. (2022) Proton motive force underpins respiration-mediated potentiation of aminoglycoside lethality in pathogenic Escherichia coli. Archives of Microbiology 204: 120. (ROS and membrane polarity measurements via flow cytometry, viability/growth assays).

Yucel, B, Robinson, G.K, Shepherd, M. (2020) The copper-responsive ScsC protein of Salmonella promotes intramacrophage survival and interacts with the arginine sensor ArtI. FEBS J. 287, 3827-3840. (Macrophage survival assays).