The rise of an intestinal epidemic

Clostridium difficile is an intestinal pathogen and a major cause of antibiotic-associated diarrhoea. In epidemics in recent years, hypervirulent ribotypes that cause severe disease have emerged, but the factors that contribute to their emergence are unclear. In this study, Robert Britton and colleagues show that two phylogenetically distinct hypervirulent ribotypes, RT027 and RT078, have independently acquired mechanisms to metabolize low concentrations of the disaccharide trehalose. The team also show that this ability to metabolize trehalose correlates with disease severity in a humanized mouse model. These data suggest a correlation between the emergence of these ribotypes and the widespread adoption and use of trehalose as a sugar additive in the human diet.