Molecular variability in C. difficile large clostridial toxins
from: Clostridia: Molecular Biology in the Post-genomic Era (Edited by: Holger Brüggemann and Gerhard Gottschalk). Caister Academic Press, U.K. (2009)
Clostridium difficile, as all clostridia, is a toxin producing microorganism and the toxins are the main virulence factors. In early eighties it was clear that two large toxins are produced by bacterium and epidemiological studies have indicated that strains either produce both toxins (toxin A, TcdA, and toxin B, TcdB) or none of them. Toxigenic strains were usualy associated with the disease, while nontoxigenic were not. Few years later, however, this simple situation changed as strains producing only TcdB or strains producing an additional toxin (binary toxin CDT) were described. Such strains with unusual toxin production pattern were subsequently found to have changes in the genomic PaLoc region encoding the toxins TcdA and TcdB. These changes are the basis for a method that distinguish C. difficile strains into toxinotypes. The variability of genes coding for large clostridial toxins (LCTs) had consequences in changes of laboratory diagnosis, changes in understanding of the role of both toxins in the pathogenesis, in structure function relationships and partialy in understanding of the evolutions of LCTs read more ...