Comparing the genomes of C. difficile infecting hundreds of patients in Oxfordshire reveals less transmission within hospitals than previously thought

Clostridium difficile is a bacterium that can cause life-threatening diarrhoea, especially when it infects the elderly. In order to limit its burden on public health, it is vital to understand how this pathogen spreads. One widely-held assumption is that most transmission of the bacteria occurs mostly between symptomatic patients during their stays in hospital, although this has not been formally tested.

In this study, genomes of C. difficile were sequenced from hundreds of infection cases occurring in Oxfordshire between 2006 and 2010. By comparing these genomes, it was possible to test whether or not transmission happened directly from one patient to another. However, the results showed that the genomes often do not match sufficiently to indicate recent transmission. This suggests that most acquisitions of these bacteria do not occur from other symptomatic patients in hospital, which has important implications for the direction of further research. For example, asymptomatic carriers may play a key role in the transmission of C. difficile.

This study was carried by members of the Modernising Medical Microbiology consortium which is based at the University of Oxford. The lead author, Dr Xavier Didelot, has recently joined the MRC Centre for Outbreak Analysis and Modelling.

Xavier Didelot, David Eyre, Madeleine Cule, Camilla Ip, Azim Ansari, Dai Griffiths, Alison Vaughan, Lily O'Connor, Tanya Golubchik, Elizabeth Batty, Paolo Piazza, Daniel Wilson, Rory Bowden, Peter Donnelly, Kate Dingle, Mark Wilcox, Sarah Walker, Derrick Crook, Tim Peto, Rosalind Harding, Microevolutionary analysis of Clostridium difficile genomes to investigate transmission, Genome Biology 2012, 13:R118 (21 December 2012)