P. Vandijck et al., GENOTYPING OF OUTBREAK-RELATED AND SPORADIC ISOLATES OF CLOSTRIDIUM-DIFFICILE BELONGING TO SEROGROUP-C, Journal of clinical microbiology, 34(12), 1996, pp. 3049-3055
Serogroup C of Clostridium difficile is the serogroup most frequently
related to outbreaks. Fifty-six toxigenic serogroup C isolates of C. d
ifficile were genotyped by ribotyping PCR (ribo-PCR), random amplified
polymorphic DNA (RAPD) assay, and pulsed-field gel electrophoresis (P
FGE). Thirty-five of the 56 isolates were recovered from four unrelate
d outbreaks (Belgium, 1987, 1992, and 1995; France, 1992 to 1993), 7 d
erived from a spatiotemporal cluster in Cotonou, Benin (1992), and 14
were sporadic isolates. The serogroup C reference strain, also isolate
d during an outbreak (Belgium, 1983), was genotyped too. Ribo-PCR, the
RAPD assay, and PFGE generated 2, 5, and 11 major genotypes, respecti
vely. Combination of the three methods finally yielded 13 general type
s, although ribo-PCR did not play any role in enhancing resolution. Th
ree general types were recovered from all the isolates from the five o
utbreaks and the cluster, with two types being predominant. The 14 spo
radic serogroup C isolates were divided into 11 overall genotypes. The
se results indicate that genotyping methods, and more particularly the
combination of the RAPD assay and PFGE, can resolve genetic diversity
within toxigenic, serogroup C C. difficile strains. Also, this study
suggests that outbreak-related serogroup C strains are limited to a fe
w genetically stable and apparently very widely (internationally and i
ntercontinentally) distributed genotypes.