Exploiting Bacteriophages to Tackle Clostridium difficile Infection

Meader, Emma (2013) Exploiting Bacteriophages to Tackle Clostridium difficile Infection. Doctoral thesis, University of East Anglia.

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Abstract

Clostridium difficile infection (CDI) currently affects around 20,000 people
each year, in healthcare institutions and in the community, and will often
follow disruption of the gut microbiome. Current treatment strategies call for
the use of further antibiotics, of which there is a limited choice. There is a
need for additional remedial and prophylactic solutions with greater specificity
and low levels of toxicity and resistance.
This thesis describes the pathogenesis of CDI, the current treatment
strategies and navigates the growing body of studies investigating the
potential use of phage. The project involved extensive screening including
faecal samples and environmental sources in an attempt to identify novel
phages of C. difficile and documents efforts to improve the therapeutic
capacity of a selected phage, ФCD27, by mutagenesis. No exclusively lytic
phages were isolated or obtained following mutagenesis with ethylmethane
sulphonate, hydroxylamine or sodium pyrophosphate.
Batch fermentation models of CDI showed that a prophylactic approach to
phage therapy of CDI offers a higher efficacy than a remedial regime. A
continuous model of CDI in a colon model was successfully produced and
demonstrated variable efficacy rates from no apparent decrease in the burden
of C. difficile to a reduction to below the limit of detection by culture, with no
detrimental effect on commensal microbiota. The lysogenic capacity of
ФCD27 appeared to prevent clearance of C. difficile in the models, but some
strains containing the prophage exhibited reduced toxin production
phenotypically. A possible mechanism of this altered phenotype included the
action of ФCD27 repressor proteins on the promoter regions of C. diffiicle
toxin genes or regulatory elements, but affinity of a candidate repressor,
ORF44, to PaLoc constituents was not demonstrated.
Studies have also demonstrated the ability of ФCD27 to prevent outgrowth of
germinating C. difficile spores, thus potential as an environmental
decontaminant.
iii
The findings of the project and the future prospects of phage therapy as an agent against CDI are discussed.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Users 2259 not found.
Date Deposited:	13 Mar 2014 10:23
Last Modified:	13 Mar 2014 10:23
URI:	https://ueaeprints.uea.ac.uk/id/eprint/48147
DOI:

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