Watkin, Samuel James; (2025) Investigating trends in hospital surface microbial contamination to inform infection prevention and control practice. Doctoral thesis (Ph.D), UCL (University College London).

Text Sam Watkin PhD Thesis - For Deposit.pdf - Accepted Version Access restricted to UCL open access staff until 1 June 2026. Download (7MB)

Abstract

Healthcare associated infections (HCAIs) present a significant threat to patient safety, with evidence demonstrating the role of surfaces in the persistence and transmission of pathogens. There is a lack of guidance however on how to collect samples from surfaces in the clinical setting for pathogen detection. This thesis aims to investigate trends in microbial contamination on hospital surfaces, facilitating the development of surface sampling guidance for use by infection prevention and control (IPC) teams to investigate surface pathogen loading. Analysis of microbiological samples collected from multiple clinical spaces identified highly varied patterns of microbial contamination. Contamination at high bioburdens with varied community diversities was observed, with a range of microorganisms detected. Microbial transfer pathways were investigated using DNA surrogate markers, revealing multiple dissemination patterns across clinical units. Markers inoculated onto high-risk sites showed the greatest dissemination across sites across units. On an oncology day case unit, markers inoculated on patient use and treatment-associated sites showed significant co-location, compared to limited detection of these on the inpatient haematology/oncology unit. Detections of the marker inoculated on a portable workstation on a cardiac intensive care unit indicated transfer associated with the movement of the equipment through the clinical space. In order to ensure the utility of the surface sampling guidance developed here, focus groups of staff who would be involved in surface sampling were undertaken. An absence of clear training and guidance in environmental IPC practice was highlighted, alongside a requirement for standardised sampling and processing methods. The findings of this research were synthesised and a framework for sample collection from surfaces in the clinical setting was proposed, covering key aspects of sample collection and results interpretation. This will result in the better identification of risks posed by surface pathogen contamination, informing clinical risk assessments and supporting IPC decision making, improving patient safety.

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