Development of Multiplex PCR for Simultaneous Detection of Three Pathogenic Shigella Species

Background: Shigella species are among the common causes of bacterial diarrhoeal diseases. Traditional detection methods are time-consuming resulting in delay in treatment and control of Shigella infections thus there is a need to develop molecular methods for rapid and simultaneous detection of Shigella spp. In this study a rapid multiplex PCR were developed for simultaneous detection of three pathogenic Shigella species. Methods: For detection of Shigella spp., a pair of primers was used to replicate a chromosomal sequence. Three other sets of primers were also designed to amplify the target genes of three most common species of Shigella in Iran including S. sonnei, S. flexneri and S. boydii. The multiplex PCR assay was optimized for simultaneous detection and differentiation of three pathogenic Shigella species. The assay specificity was investigated by testing different strains of Shigella and other additional strains belonging to non Shigella species, but responsible for foodborne diseases. Results: The Shigella genus specific PCR yielded the expected DNA band of 159 bp in all tested strains belonging to four Shigella species. The standard and multiplex PCR assays also produced the expected fragments of 248 bp, 503 bp, and 314 bp, for S. boydii, S. sonnei and S. flexneri, respectively. Each species-specific primer pair did not show any cross-reactivity. Conclusion: Both standard and multiplex PCR protocols had a good specificity. They can provide a valuable tool for the rapid and simultaneous detection and differentiation of three most prevalent Shigella species in Iran.