Principal Supervisor: Dr Jack BryantLink opens in a new window
Co-supervisor: Manuel Banzhaf
PhD project title: Effect of antimicrobial materials on the development of antimicrobial resistance among ESKAPE pathogens
University of Registration: University of Birmingham
The increase in antimicrobial resistance (AMR) is a recognised global problem. Current forecasts project that by 2050, it will have led to 10 million preventable deaths, and cost the global economy in excess of £66 trillion. Research and development across different sectors will be key in tackling this problem. We have developed a novel antimicrobial surface which incorporates biocides onto surfaces, is very durable and can last for years. We have demonstrated that the surfaces are effective in killing bacteria, fungi and viruses (including SARS-CoV-2) in seconds. It is considerably faster than any other commercial technology and is resistant to abrasion and common cleaning practices. Our initial studies have also demonstrated that when surfaces incorporate biocides such as chlorhexidine digluconate they are as effective at killing chlorhexidine resistant bacteria as they are at killing naïve bacteria. The technology has been shown to be efficacious in both lab-based and “real world” studies, therefore proving to be highly effective at decreasing the spread of bacteria.
Despite the extremely promising progress made so far with this technology, the widespread use of biocides raises concerns for the potential of antimicrobial resistance and further work is required. The aim of this project would be to investigate the mechanism of action of chlorhexidine and the mechanism by which surfaces inhibit bacterial survival. We will also investigate whether this differs from the effect of the biocide in liquid culture. Depending on progress, the Ph.D. candidate can choose to target the following research objectives:
Objective 1: Compare the mechanisms by which the key ESKAPE pathogens develop resistance to chlorhexidine in either liquid medium or attached to surfaces.
The project will use lab-based evolution and next-generation sequencing to compare the mechanisms by which the key ESKAPE pathogens develop resistance to chlorhexidine in liquid medium. This will be compared to the significant effect of chlorhexidine attachment to our novel surface technology on the efficacy of the antibiotic.
Training: Surface coupling, microscopy, culture of several bacterial species, lab-based evolution, next-generation sequencing.
Objective 2: Characterise the gene networks that become essential for bacterial survival in the presence of chlorhexidine.
We will use high-throughput genetics approaches, such as Transposon Directed Insertion-site Sequencing to characterise the gene networks that become essential for bacterial survival in the presence of sub-inhibitory concentrations of chlorhexidine. We will also use gene over-expression libraries to identify targets for chlorhexidine killing of bacteria. These gene “hits” will be validated and investigated further using a range of biochemistry and molecular microbiology approaches. Together, the results of Objective 1 and 2 will define the mechanism of action for chlorhexidine against gram-negative pathogens, which is an existing gap in the literature. These aims will also establish whether mechanisms of resistance to chlorhexidine in liquid media also provide resistance to antimicrobial surfaces.
Training: High-throughput genetics (TraDIS), data analysis, biochemistry.
Objective 3: Screen an existing bank of environmental/clinical isolates for resistance to chlorhexidine.
While the first two objectives will address lab-based evolution of resistance within closed genetic systems, the final objective will aim to characterise mechanisms of resistance arising within the environment. We will use chemical genomics and robotic handling systems to screen an existing bank of environmental/clinical isolates for resistance to chlorhexidine in liquid medium and characterise these mechanisms of resistance by genome sequencing. We will then identify whether any of these strains are capable of survival on antimicrobial surfaces and recapitulate the resistance mechanisms within a naive background. This will allow us to establish whether any of the mechanisms of resistance identified in environmental isolates will facilitate growth on antimicrobial surfaces.
Training: Experience of work with a range of microorganisms, robotic handling systems, high-throughput screening, genome manipulation.
BBSRC Strategic Research Priority: Understanding the rules of life – Microbiology
Techniques that will be undertaken during the project:
Surface coupling and surface analysis
High-throughput genetics: Transposon-directed insertion site sequencing (TraDIS)
Molecular microbiology: DNA manipulation, protein purification, western blotting etc.