Clostridium difficile infection; establishment, prevention and the role of the microbiota

William Ferreira

Research output: ThesisDoctoral Thesis

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Abstract

Clostridium difficile is a leading cause of nosocomial, antibiotic-associated, diarrhoea in industrialised countries. C. difficile spores are dormant and resistant structures responsible for the colonisation and persistence of C. difficile infection (CDI) within patients as well as the transmission between them. This thesis examines firstly, the role of a C. difficile spore coat protein, CotE, in the establishment of CDI, and secondly, the role of allochthonous Bacillus within the GI tract in suppressing CDI. CotE is a protein displayed on the C. difficile spore surface which carries two functional elements, an N-terminal peroxiredoxin and a C-terminal chitinase domain. Using isogenic mutants, it was demonstrated in vitro and ex vivo that CotE enables binding of spores to mucus by direct interaction with mucin and contributes to its degradation. In animal models of CDI, it was shown that when CotE was absent, both colonisation and virulence were markedly reduced. It is demonstrated here that the attachment of spores to the intestine is essential in the development of CDI. The developments of infection within the host GI tract requires germination of the spore, followed by outgrowth of the vegetative cell; a process which requires a multitude of factors to favour C. difficile proliferation. In a series of experiments, it was shown that environmentally acquired Bacillus help to suppress CDI by the production of lipopeptides in vivo with activity against C. difficile and that the use of antibiotics abrogates this phenomenon. Using hamster and mouse models, it was demonstrated that the administration of these Bacillus provides complete colonisation resistance against CDI in clindamycin treated animals. Reversed-phase high-performance liquid chromatography, dynamic light scattering and MALDI-TOF analysis identified the active molecules to be a micellar complex of lipopeptides comprised of chlorotetaine, iturins, fengycins and surfactins. Through this work, it is demonstrated that the attachment of spores to the intestine is essential in the development of CDI and suggests a direct role for the spore in the establishment and promotion of disease.
Original languageEnglish
QualificationPh.D.
Awarding Institution
  • Royal Holloway, University of London
Supervisors/Advisors
  • Cutting, Simon, Supervisor
Thesis sponsors
Award date1 Apr 2020
Publication statusUnpublished - 9 Sept 2019

Keywords

  • Microbiology
  • Biochemistry
  • C. difficile
  • Bacillus
  • Microbiota

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