Aim: To determine the prevalence of clinically important toxin-variant (A-negative, B-positive)
Clostridium difficile strains in our institution; a 600-bed university-affiliated hospital in Dublin.
Methods: We prospectively studied all consecutive patients with nosocomial C.difficile diarrhoea from July to December 2003. C.difficile was cultured from faecal specimens. Toxin-specific ELISA's, and PCR were used to
analyse C.difficile isolates.
Results: We prospectively identified 70 cases of C.difficile diarrhoea. At least 5 patients developed severe pseudomembranous colitis, 3 of whom
died. Recurrent C. difficile diarrhoea occurred in 28 patients (40%). All isolates were positive using the toxin-A/B
ELISA. 95% of C.difficile isolates were negative using the toxin-A ELISA. The entire toxin A gene (tcdA) gene was studied by PCR. C.difficile variant strains were detected in 95% of patients. A deletion of approximately 1.7
kb was found at the 3' end of the toxA gene, similar to the deletion in PCR-017 strains (e.g., C.difficile serotype F, 1470). In patients with recurrent diarrhoea (40%), the initial and recurring
strain was toxin-variant in all but one case.
Conclusions: Toxin-variant C.difficile appears to be endemic in our institution. This strain type is associated with disease
spectrum and recurrence rates similar to that caused by toxin A+B+ strains of C.difficile.
