Development of a PCR test for rapid diagnosis of contagious equine metritis

In order to establish a rapid diagnostic method for contagious equine metri tis (CEM), we developed and evaluated a polymerase chain reaction (PCR) tes t. Species-specific PCR primer sets were derived from the DNA sequence of a cloned DNA fragment of Taylorella equigenitalis that did not hybridize wit h the genome of a taxomonically related species, Oligella urethralis. Singl e step PCR with primer set P1-N2 and two-step semi-nested PCR with primer s ets P1-N2 and P2-N2 detected as low as 100 and 10 CFU of the bacteria, resp ectively. Single-step PCR detected T. equigenitalis from genital swabs of e xperimentally infected mares with sensitivity comparable to that of bacteri al isolation. Furthermore, two-step PCR was more sensitive than the culture method. Upon examination of field samples, 12 out of 3,123 samples were po sitive by single-step PCR while only 2 were positive by bacterial culture. The 12 PCR-positive samples originated from 5 mares, of which 3 animals wer e considered to be carriers based on previous bacteriologic and serologic d iagnoses for GEM. The PCR test described in this study would provide a spec ific and highly sensitive tool for the rapid diagnosis of CEM.