Changing Epidemiology of Clostridium difficile and Emergence of New Virulent Strains

infection (CDI) is constantly changing and is influenced by antibiotic usage pat-terns, healthcare patient environment, and emergence of new strains. Between 1982 and 1991, 4 outbreak periods were noted in 1 hospital in Minnesota, each marked by clusters of specific strains, des-ignated by restriction endonuclease typ-ing (REA) as groups B and K (both type 053 by polymerase chain reaction [PCR] ribotyping) [1]. In addition to these out-breaks, there was a background incidence of CDI due to a wide variety of C. difficile strains including 6 isolations of a REA group BI (ribotype 027) strain, a strai