[Typing system for Clostridium difficile by western blotting using antisera against ten different serogroup strains]

Western blotting using antisera against each of reference ten serogroups was evaluated as a typing system for Clostridium difficile. A total of 164 isolates of C. difficile (114 epidemiologically unrelated and 50 isolates from a hospital outbreak in New York) were tested. Blotting patterns for the ten reference strains showed serogroup-specific bands located in the 30-60 kDa when each homologous antiserum was used. At greater than 60 kDa, variations in each serogroups were observed; these variations were used for subserogrouping the isolates. Serogroup A, G, H, and K were most frequently recovered in the group of epidemiologically unrelated isolates. Subserogroup G-1 strains of serogroup G was isolated from 28 of 36 patients (78%) of the hospital outbreak. The result suggested that the subserogroup G-1 strain was the major cause of infection in the hospital outbreak. A total of 46 of the 114 unrelated isolates (40.4%) and 9 of 50 outbreak isolates (18%) did not react with any of reference antisera and classified as nontypable. The western blotting was found to be useful not only as an epidemiological tool but as a typing system for C. difficile.