Mitchell, Holly Diana;
(2020)
Identifying and characterising sexual transmission of enteric pathogens in men who have sex with men using classical and molecular epidemiological methods.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Enteric pathogens are transmitted via the faecal-oral route and commonly cause diarrhoea and/or vomiting. In recent years, there have been numerous outbreaks in men who have sex with men (MSM), primarily Shigella spp., often associated with antimicrobial resistance. My research aimed to investigate the characteristics, risk factors and burden of bacterial enteric pathogens (BEPs) in MSM that could inform control. I conducted a cross-sectional study at a London sexual health clinic (SHC) to estimate the prevalence of BEPs in MSM and associated risk factors. I linked whole genome sequencing (WGS) data with clinical and behavioural data on reported cases of Shigella flexneri to i) characterise transmission within sexual networks of MSM and ii) validate a public health tool for identifying MSM clusters in near real-time. One in 10 predominantly asymptomatic MSM attending the SHC had a BEP detected, which was associated with higher-risk sexual behaviours. Among MSM with a BEP, presence of a genotypic marker of azithromycin resistance was associated with a history of bacterial sexually transmitted infections (STIs). In the WGS study, S. flexneri isolates from MSM largely belonged to two clades associated with genotypic markers of azithromycin resistance, with evidence of sustained transmission through sex between men. Over one third of isolates within MSM clades were from people living with HIV. The public health tool distinguished MSM from non-sexual transmission clusters. My research provides strong evidence that BEPs are transmitted sexually in MSM and asymptomatic carriage may be sustaining transmission. The findings suggest that antimicrobial treatment for STIs selected for resistance in gut organisms, emphasising the need for better antimicrobial stewardship. Phylogenetic analyses provided novel insights about S. flexneri transmission in sexual networks of MSM that could inform clinical care and public health management. Real-time identification of MSM clusters might inform the delivery of rapid and appropriate responses.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Identifying and characterising sexual transmission of enteric pathogens in men who have sex with men using classical and molecular epidemiological methods |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/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 Population Health Sciences > Institute for Global Health |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10110104 |
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