Sensitivity of the choE PCR. (A) choE amplicon obtained with various amounts of purified R. equi ATCC 6939 genomic DNA. Lane M, DNA size marker; lanes 1 to 6, serial 10-fold dilutions of the DNA preparation (lane 1, 200 ng; lane 6, 2 pg). (B) choE amplicons obtained with various quantities of R. equi ATCC 6939 bacterial cells. Lane M, DNA size marker; lanes 1 to 5, 3 × 104, 3 × 103, 3 × 102, 30, and 3 CFU, respectively.