Nightmare in the ward: difficult infection.

is a Gram-positive, anaerobic, spore-forming bacillus. It is isolated in 80% of the stools of children and infants and in 3% of healthy adults. It causes gastrointestinal tract infections and affects patients who make prolonged use of antibiotics. It causes colitis with symptoms ranging from diarrhoea to pseudomembranous colitis to toxic megacolon. The main virulence factors of are toxin A, toxin B, and binary toxin. It is one of the most common nosocomial infections but in recent years, however, many infections have also been found at the community level. They are associated not only with a high risk of mortality but also with a prolongation of hospital stay. One of the critical aspects of infections is also represented by the high frequency of relapses. Consequently, the economic impact is significant. Specific situations constitute risk factors for infection, such as exposure to antibiotic therapy in the previous months, in particular fluoroquinolones, third-generation cephalosporins, clindamycin, repeated hospitalizations in healthcare facilities, including long-term care, as well as the patient's clinical conditions such as comorbidities, age >65, chemotherapy and immunosuppressive treatments, recent surgery of any type, and pump inhibitor therapy. Treatment protocols will be described in the paper.