Phenotypic and genotypic diversity of the flagellin gene (fliC) among Clostridium difficile isolates from different serogroups

Phenotypic and genotypic diversity of the flagellin gene (fliC) of Clostrid ium difficile was studied in 47 isolates from various origins belonging to the serogroups A, B, C, D, F, G, H, I, K, X, and S3. Electron microscopy re vealed 17 nonflagellated strains and 30 flagellated strains, PCR and revers e transcription-PCR demonstrated that the flagellin gene was present in all strains and that the fliC gene was expressed in both flagellated and nonfl agellated strains. Southern blotting showed the presence of only one copy o f the gene and three different hybridization patterns. DNA sequence analysi s of fliC from the strains belonging to serogroups C, D, and X, representat ive of each profile, disclosed great variability in the central domain, whe reas the N- and C-terminal domains were conserved. The variability of the f lagellin gene fliC was further studied in the isolates by PCR-restriction f ragment length polymorphism (RFLP) analysis. Nine different RFLP groups wer e identified (I to IX), among which three (I, VII, and VIII) corresponded t o numerous serogroups whereas the six others (II, III, IV, V, VI, and IX) b elonged to a single serogroup, Flagellin gene RFLP analysis could constitut e an additional typing method employable in conjunction with other typing m ethods currently available.