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Updated: Apr 1, 2026

Cefoperazone-treated Mouse Model of Clinically-relevant Clostridium difficile Strain R20291
Published on: December 10, 2016
Clostridium difficile: New Insights into the Evolution of the Pathogenicity Locus
Marc Monot1, Catherine Eckert2,3, Astrid Lemire2,3
1Laboratoire Pathogenèse des Bactéries Anaérobies, Institut Pasteur, Paris, France.
Abstract:
The major virulence factors of Clostridium difficile are toxins A and B. These toxins are encoded by tcdA and tcdB genes, which form a pathogenicity locus (PaLoc) together with three additional genes that have been implicated in regulation (tcdR and tcdC) and secretion (tcdE). To date, the PaLoc has always been found in the same location and is replaced in non-toxigenic strains by a highly conserved 75/115 bp non-coding region. Here, we show new types of C. difficile pathogenicity loci through the genome analysis of three atypical clinical strains and describe for the first time a variant strain producing only toxin A (A(+)B(-)). Importantly, we found that the PaLoc integration sites of these three strains are located in the genome far from the usual single known PaLoc integration site. These findings allowed us to propose a new model of PaLoc evolution in which two "Mono-Toxin PaLoc" sites are merged to generate a single "Bi-Toxin PaLoc".
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