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Title: Effect of epicatechin gallate on staphylococcal virulence in vivo
Author: Stevens, C. S.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen; it is endemic in hospitals all over the world and can also be found in community settings. The prevention and treatment of MRSA infections has become increasingly difficult due to the ability of these bacteria to develop resistance against all classes of antibiotics. There is an urgent need for alternative ways to treat antibiotic resistant pathogens which do not expose the pathogen to the same selective pressure as antibiotics do. This can be achieved by modification of the bacterial phenotype which will then result in a ‘less fit’ phenotype which may enable the host to successfully remove the pathogen Previous studies have shown that epicatechin gallate (ECg), a component of green tea, is capable of sensitizing MRSA to β-lactam antibiotics. The aim of this study was to develop a zebrafish embryo model for in vivo determination of the effects of ECg on MRSA infections. An increase in zebrafish embryo survival was found after injection of bacteria grown in the presence of ECg. We hypothesised that ECg-grown EMRSA-16 are more susceptible to the innate immune system of the zebrafish embryos in comparison to untreated bacteria. Confocal microscopy revealed modified bacteria within zebrafish granulocytes and four distinct immune cell populations were identified using flow cytometry. An increase in induction of the respiratory burst and a reduction in IL-1β expression determined that bacteria pretreated with ECg are less likely to induce an inflammatory response and are more readily eliminated by the immune system compared to untreated MRSA cells. The results obtained in this study make an important contribution to elucidating the immune-modulatory effects of ECg. They suggest that exposure to ECg reduces the capacity of MRSA to avoid the innate defences of the zebrafish embryo and may therefore enable the modification of the phenotype.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available