FIG. 1.

PCR amplification of tcdA fragment A3 in the new toxinotypes XVI and XVIII to XX. (In new toxinotype XVII the A3 fragment could not be amplified.) The strain designation and toxinotype are shown above the gel lanes. A3 PCR fragment types as determined by size and restriction patterns (data not shown) are indicated below the gel lanes. All shown A3 PCR fragments were shorter than the fragment obtained with reference strain VPI 10463. Strains GAI 00166 and SUC 36 represent two new deleted A3 fragment types, 11 and 10, respectively. Strains TR 13 and TR 14 are identical in length to the known A3 PCR fragment types (5 and 6). Strain 57267 was used here as a control for differentiation between A3 PCR fragments pattern 6 and 5, which are very similar in deletion size.