Typing scheme for Clostridium difficile: its application in clinical and epidemiological studies.

Epidemiological studies of Clostridium difficile diarrhoeal disease have been hindered by the lack of a typing scheme for this organism. A typing method based on the incorporation of sulphur-35-labelled methionine into cellular proteins and their separation by sodium dodecylsulphate/polyacrylamide gel electrophoresis showed clear pattern differences between strains, and nine distinct groups within the C difficile species were established. 98% of 250 clinical strains derived from four hospitals were typable. Group X was the commonest group and was associated with outbreaks of pseudomembranous colitis and antibiotic-associated colitis in two hospitals. Groups A-D were isolated predominantly from mothers and newborn infants. In outbreaks of antibiotic-associated colitis in oncology and orthopaedic wards the same strains, group X and group E, respectively, were isolated from patients and their environment, providing strong evidence of cross-infection between patients and of hospital acquisition of C difficile.