Development of a diagnostic shuttle PCR test targeting the Streptococcus equi SeM gene

Abstract

A shuttle PCR test targeting the conserved region of the SeM gene of Streptococcus equi was developed as a method for detecting this bacterium from horses. An amplicon 289 bp in size was detected from 137 strains of S. equi, but was not seen in 517 strains of other bacteria, including S. zooepidemicus and in 227 nasal mucosal swabs taken from horses which S. equi had not been isolated. A comparative examination using 12 strains of S. equi in serial dilution and 73 swabs taken from the nasal mucosa of horses from which S. equi had been isolated showed the sensitivity of our PCR was slightly inferior to conventional PCR described in a previous report, even though it was enough to use as a diagnostic tool. In conclusion, we suggest that the PCR method described here has advantages with respect to specificity and sensitivity as a diagnostic test for strangles.