TABLE 1

Bacterial strains and plasmids

Strain or plasmidRelevant detailsReference or source
C. difficile VPI 10463A known very-high-level toxin producer39
C. difficile R20291Wild type; PCR ribotype 02740
C. difficile UK6An epidemic strain (provided by Dale Gerding and Abraham L. Sonenshein) isolated in the United Kingdom44
CD2001Nontoxigenic C. difficileMichel R. Popoff, Institut Pasteur
CCUG37780Michel Delmée (UCL, Belgium) to the Culture Collection of the University of Gothenburg (CCUG), Sweden
CCUG37785
CCUG37787
Vector pHis1525Cloning vectors; the xylose operon is used as regulatory element41
pRPF144Based on the pMTL960 backbone, subcloned into pBL13942
pBL139E. coli-C. difficile shuttle vector43