FIG. 2.

Typical length polymorphisms and RFLPs found in repetitive regions of tcdA (A3 PCR). The lane numbers indicate the type of fragment. Type 1 represents strain VPI 10463, type 7 represents the deletion described for serogroup F strains. Two other large deletions are observed in the uncut PCR fragment (types 5 and 6). With EcoRI further differences in this PCR fragment are obtained: the RFLPs in types 3 and 4 are probably due to minor deletions, and in type 2, the restriction fragments are polymorphic because of one missing EcoRI site. Types 5, 6, and 7 were not restrictable with EcoRI. In all A3 fragments the SpeI restriction sites are conserved.