Clostridium difficile Toxinotyping

Clostridium difficile shows considerable variability in the PaLoc region encoding two main virulence factors, toxins TcdA and TcdB. Strains with changes in PaLoc are defined as variant toxinotypes and currently 27 such groups are recognized (I to XXVII). Toxinotype 0 includes strains with PaLoc identical to the reference laboratory strain VPI 10463. Toxinotyping is a RFLP-PCR-based method using a combination of restriction patterns of part of tcdB and tcdA genes for determination of toxinotype. Variations in PaLoc can affect the toxin production or could result in production of toxins with altered properties.