Two year analysis of Clostridium difficile ribotypes associated with increased severity.

BACKGROUND: Certain Clostridium difficile ribotypes have been associated with complex disease phenotypes including recurrence and increased severity, especially the well-described hypervirulent ribotype RT027. In this study we set out to determine the pattern of ribotypes causing infection and association if any with severity.

METHODS: All faecal samples submitted to a large diagnostic laboratory for C. difficile testing between 2011 and 2013 were subject to routine testing and cultured. All C. difficile isolates were ribotyped and associated clinical and demographic patient data were retrieved then linked to ribotyping data.

RESULTS: A total of 86 distinct ribotypes were identified from 705 isolates of C. difficile. Ribotypes RT002 and RT015 were the most prevalent (22.5%, n=159). Only five isolates (0.7%) were the hypervirulent RT027. Ninety of 450 (20%) patients with clinical information available died within 30-days of C. difficile isolation. Ribotype RT220, one of the ten commonest ribotypes, was associated with elevated median C-reactive protein and significantly increased 30-day all-cause mortality when compared with ribotypes RT002 and RT015, and with all other ribotypes found in the study.

CONCLUSIONS: A wide range of C. difficile ribotypes were responsible for C. difficile infection presentations. Although C. difficile-associated mortality has reduced in recent years, expansion of lineages associated with increased severity could herald increases in future mortality. Enhanced surveillance for emerging lineages such as RT220 that are associated with more severe disease is required, with genomic approaches to dissect pathogenicity.