Engineering new approaches for pathogen separation and detection to tackle antimicrobial resistance

Farthing, Andrew G. (2024) Engineering new approaches for pathogen separation and detection to tackle antimicrobial resistance. PhD thesis, University of Glasgow.

Abstract

Sepsis and antimicrobial resistance are global health crises. Sepsis, defined as a lifethreatening, dysregulated host response to infection, is responsible for one fifth (11 million) of all global deaths. The importance of immediate antimicrobial therapy in sepsis management is well documented, with 80% of patients surviving if they receive adequate antimicrobial therapy within one hour of documented hypotension. For each hour of subsequent delay for the following 6 hours there is an associated decrease in survival of 7.6%; at this rate, the chance of surviving more than 30 hours is less than 10%. This reliance on rapid, broad spectrum antimicrobial therapy necessary to treat sepsis accelerates the spread of resistance which is predicted to result in one death every 3 seconds due to a drug-resistant infection by 2050, resulting in 10 million more global deaths each year. Rapid and accurate pathogen identification remains a significant challenge in sepsis management due to the low concentration of pathogens in the bloodstream (1-1000 colony forming units/ml). This necessitates a lengthy blood culture step which typically takes 1-5 days. This thesis addresses the diagnostic bottleneck in sepsis treatment by exploring innovative methods for pathogen detection and separation. Focusing on the Glasgow Royal Infirmary’s clinical diagnostics workflow, I aimed to develop a novel sample preparation assay for blood samples by leveraging Toll-like Receptors 2, 4 and 9. These receptors, known for their broad pathogen recognition capabilities, were investigated for their potential to bind and detect Gram-positive bacteria, Gram-negative bacteria, and microbial DNA directly from blood samples. By exploiting the advantages of imaging flow cytometry for high-throughput detection of small particles, I developed and optimised assays to accurately quantify the binding capacity of TLRs to whole bacteria, and pathogen DNA. This work highlights the diagnostic and therapeutic potential of Toll-like receptors to be used, not only for pathogen detection, but also as possible biomarkers for the sepsis immune response, offering a novel, double-edged approach to diagnostics. Further optimisation may one day reduce the need for lengthy blood cultures, facilitating antimicrobial stewardship and helping pave the way for more effective sepsis management.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Supported by funding from the the LKAS fellowship.
• Subjects: Q Science > QR Microbiology; T Technology > TA Engineering (General). Civil engineering (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Clark, Professor Alasdair, Jimenez, Dr. Melanie and Goodyear, Professor Carl
• Date of Award: 2024
• Depositing User: Theses Team
• Unique ID: glathesis:2024-84533
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 02 Sep 2024 13:16
• Last Modified: 02 Sep 2024 13:17
• Thesis DOI: 10.5525/gla.thesis.84533
• URI: https://theses.gla.ac.uk/id/eprint/84533