The role of toxin A and toxin B in Clostridium difficile infection

Research output: Contribution to journalArticlepeer-review


  • Sarah A Kuehne
  • Stephen T Cartman
  • John T Heap
  • Michelle L Kelly
  • Alan Cockayne
  • And 1 others
  • Nigel P Minton

External organisations

  • University of Nottingham


Clostridium difficile infection is the leading cause of healthcare-associated diarrhoea in Europe and North America. During infection, C. difficile produces two key virulence determinants, toxin A and toxin B. Experiments with purified toxins have indicated that toxin A alone is able to evoke the symptoms of C. difficile infection, but toxin B is unable to do so unless it is mixed with toxin A or there is prior damage to the gut mucosa. However, a recent study indicated that toxin B is essential for C. difficile virulence and that a strain producing toxin A alone was avirulent. This creates a paradox over the individual importance of toxin A and toxin B. Here we show that isogenic mutants of C. difficile producing either toxin A or toxin B alone can cause fulminant disease in the hamster model of infection. By using a gene knockout system to inactivate the toxin genes permanently, we found that C. difficile producing either one or both toxins showed cytotoxic activity in vitro that translated directly into virulence in vivo. Furthermore, by constructing the first ever double-mutant strain of C. difficile, in which both toxin genes were inactivated, we were able to completely attenuate virulence. Our findings re-establish the importance of both toxin A and toxin B and highlight the need to continue to consider both toxins in the development of diagnostic tests and effective countermeasures against C. difficile.


Original languageEnglish
Pages (from-to)711-3
Number of pages3
Issue number7316
Publication statusPublished - 7 Oct 2010


  • Animals, Antibodies, Neutralizing, Bacterial Toxins, Cercopithecus aethiops, Clostridium Infections, Clostridium difficile, Cricetinae, Disease Models, Animal, Enterotoxins, Gene Deletion, HT29 Cells, Humans, Neutralization Tests, Vero Cells, Virulence, Journal Article, Research Support, Non-U.S. Gov't