The Role of the Gastrointestinal Tract Microbiota in Colonisation Resistance Against Common Enteric Pathogens in Malawian Children

Chunga, Angeziwa
(2022) The Role of the Gastrointestinal Tract Microbiota in Colonisation Resistance Against Common Enteric Pathogens in Malawian Children. Doctor of Philosophy thesis, University of Liverpool.

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Introduction: Gut microbiota disruption during early life has immediate and long-term impact on host health. Early feeding habits and pathogen exposure are important factors that can cause gut microbiota disruption. This study aimed to describe the role of gut microbiota in controlling enteric pathogens that Malawian children are exposed to, and to characterise and explore anti-infective properties of Bifidobacterium isolated from Malawian infants against Salmonella Typhimurium. Methods: The study used an enteric Taqman Array Card to detect pathogens that Malawian children aged 6 to 18 months are exposed to, 16S rRNA sequencing for microbiota profiling, whole-genome sequencing to characterise Bifidobacterium and in vitro competitive assay to explore anti-infective properties of the Malawi Bifidobacterium against an invasive Salmonella typhimurium strain. Results: The study has demonstrated that healthy Malawian children are exposed to multiple enteric pathogens that are mostly not associated with clinical symptoms. Apart from Giardia, EAEC and B. fragilis, most of these pathogens do not affect gut microbiota composition. In addition, the data demonstrate that Bifidobacterium is predominant in Malawian children, especially those that are exclusively breastfeeding. Malawian breastfeeding infants are predominantly colonised by Bifidobacterium longum possessing a wide range of human milk oligosaccharide digesting genes. Exploratory data show that Malawian Bifidobacterium strains possess anti-infective properties against Salmonella Typhimurium. Conclusion: Malawian children are asymptomatically exposed to multiple enteric pathogens that may affect gut microbiota composition. Bifidobacterium from Malawian breastfeeding infants possess HMOs that may be important for colonisation resistance against important enteric pathogens.

Item Type: Thesis (Doctor of Philosophy)
Divisions: Faculty of Health and Life Sciences
Depositing User: Symplectic Admin
Date Deposited: 21 Nov 2022 11:56
Last Modified: 18 Jan 2023 19:43
DOI: 10.17638/03166232