RESUMEN
Clostridium difficile has become the most frequent hospital-acquired infection in North America and the EU. C. difficile infection (CDI) is present worldwide and disease awareness is increasing. In the US, EU, and Canada, in addition to hospital diagnosed disease, CDI has also been reported with increasing frequency in the community. Hypervirulent strains have increased the morbidity and mortality associated with CDI. Current treatment options are suboptimal. Of all patients treated for CDI, 20% relapse and 65% of those experiencing a second relapse become chronic cases. An association between increased serum levels of IgG antibody against toxin A and asymptomatic carriage of C. difficile provides a rationale for vaccine development. Sanofi Pasteur's C. difficile candidate vaccine is being developed for the prevention of primary disease. The target population is adults at risk of CDI, those with planned hospitalization, long-term care/nursing home residents, and adults with co-morbidities requiring frequent/prolonged antibiotic use.