Yetiş, Özge;
(2023)
The role of hospital water in the transmission of Pseudomonas aeruginosa
infection in immunosuppressed patients: Impact of interventions on healthcare
water systems, epidemiological characterisation of risk factors for nosocomial
bacteraemia and its relationship to reservoirs in the hospital environment using
longitudinal sampling, case control studies and whole-genome-sequencing.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that can colonise environmental surfaces, posing a risk of infection to immunocompromised patients. Healthcare waters are a common reservoir. Although neutropenic patients may acquire infection during their course of stay in the hospital, transmission routes are little understood. Molecular identification (PFGE, VNR, MLST, WGS) can determine the relatedness of strains between patients and hospital environment. Although outbreak investigations show indistinguishable strains between environment and patients, the mode and direction of transfer is challenging. In 2018, UCH had the highest number of hospital-onset P. aeruginosa bacteraemia cases when compared to other acute trusts in the UK. Consequently, a multi-pronged approach to describe the reservoirs, routes of transmission and epidemiological links between clinical and environmental P. aeruginosa in this healthcare setting was proposed. An enhanced monitoring programme was implemented to patient showers in augmented and nonaugmented care wards by sampling waters and drains weekly/biweekly and complemented with bespoke remediation including shower interventions and enhanced disinfection to reduce levels of water contamination. Hollow-fibre point-of-use shower filters used to mechanically sequester bacteria from shower waters were evaluated to determine in-use efficacy. In parallel, the epidemiological links between environmental and clinical P. aeruginosa strains were compared using Whole-Genome-Sequencing. The importance of patient characteristics were denoted through conditional logistic-regression matched-case-control study to determine factors affecting risk of acquiring P. aeruginosa. Biofilm-formation in showerhoses were replicated in-vitro using microtiter-well assays. Finally, short-read Illuminasequencing (WGS) of a subset of 190 environmental and clinical isolates determined their relatedness through SNP-distance-matrices and phylogenetic trees and AMR/ biofilm genes characterised. A number of novel findings are presented that challenge national guidelines for testing healthcare waters, highlight risk-factors for risk management of bacteraemia and redefine criteria for the epidemiological characterisation of spatial-temporal distribution of P. aeruginosa between clinical and environmental reservoirs.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | The role of hospital water in the transmission of Pseudomonas aeruginosa infection in immunosuppressed patients: Impact of interventions on healthcare water systems, epidemiological characterisation of risk factors for nosocomial bacteraemia and its relationship to reservoirs in the hospital environment using longitudinal sampling, case control studies and whole-genome-sequencing. |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2023. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Infection and Immunity |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10182829 |
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