Annotation This work deals with diagnostics bacterium Clostridium difficile, which is due to toxin production very significantly participate with antibiotic-associated diarrhea and pseudomembranous colitis in recent years. The disease spread as nosocomial infection and is closely related with long-term use of antibiotics. The work also prepares statistics about frequency of incidence of this disease in the University Hospital in Brno for a period of 3 months in 2010 and in recent years and compares them with published data. The general part deals with the properties of the genus Clostridium, structure and function of Clostridium difficile toxins, as well as diseases and complications caused by the effect of clostridium toxins, culture and principles of diagnostic methods for the determination of C. difficile and treatment of diseases caused by this bacteria. The practical part of this work contain working procedures most commonly used methods implemented in routine laboratories and statistics data about frequency of incidence.