Figure 1: Agarose gel electrophoresis of the PCR products tested with five primer pairs using 20 ng of genomic DNA of C. difficile R20291 as template. Each primer pair was tested individually and in combination with all 5 primer pairs in the multiplex PCR. Lane M: 100-bp DNA ladder marker. Lanes 1–5, single-plex PCR reactions using primers specific to tcdA, tcdB, cdtA, cdtB, and 16s rDNA, respectively. Lane 6: multiplex PCR with all four toxin-specific primers and 16S rDNA primers.