Clostridium difficile is one of the most important causes of healthcare acquired diarrhea. The disease spectrum caused by C. difficile infection ranges from mild, self-limited, illness to a severe, life-threatening colitis. The incidence of C. difficile associated disease has risen dramatically over the last decade, leading to increased research interest aiming at the discovery of new virulence factors and the development of new treatment and prevention regimens. This review summarizes the pathogenesis and changing epidemiology of C. difficile associated disease, the clinical spectrum and laboratory methods to diagnose C. difficile infection, and current treatment strategies.

Clostridioides difficile infection (CDI) has emerged as a major health problem worldwide. A major risk factor for disease development is prior antibiotic use, which disrupts the normal gut microbiota by altering its composition and the gut’s metabolic functions, leading to the loss of colonization resistance and subsequent CDI. Data from human studies have shown that the presence of C. difficile, either as a colonizer or as a pathogen, is associated with a decreased level of gut microbiota diversity. The investigation of the gut’s microbial communities, in both healthy subjects and patients with CDI, elucidate the role of microbiota and improve the current biotherapeutics for patients with CDI. Fecal microbiota transplantation has a major role in managing CDI, aiming at re-establishing colonization resistance in the host gastrointestinal tract by replenishing the gut microbiota. New techniques, such as post-genomics, proteomics and metabolomics analyses, can possibly determine in the future the way in which C. difficile eradicates colonization resistance, paving the way for the development of new, more successful treatments and prevention. The aim of the present review is to present recent data concerning the human gut microbiota with a focus on its important role in health and disease.

Clostridioides (Clostridium) difficile is ubiquitous in the environment and is also considered as a bacterium of great importance in diarrhea-associated disease for humans and different animal species. Food animals and household pets are frequently found positive for toxigenic C. difficile without exposing clinical signs of infection. Humans and animals share common C. difficile ribotypes (RTs) suggesting potential zoonotic transmission. However, the role of animals for the development of human infection due to C. difficile remains unclear. One major public health issue is the existence of asymptomatic animals that carry and shed the bacterium to the environment, and infect individuals or populations, directly or through the food chain. C. difficile ribotype 078 is frequently isolated from food animals and household pets as well as from their environment. Nevertheless, direct evidence for the transmission of this particular ribotype from animals to humans has never been established. This review will summarize the current available data on epidemiology, clinical presentations, risk factors and laboratory diagnosis of C. difficile infection in food animals and household pets, outline potential prevention and control strategies, and also describe the current evidence towards a zoonotic potential of C. difficile infection.