Abstract
Shigella sonnei is the most common Shigella spp. in developed areas and the second most common in undeveloped regions. In this study, a multiple cross displacement amplification (MCDA) assay was used in combination with a lateral flow biosensor (LFB) assay to detect virulent S. sonnei strains containing the ipaH and wbgX genes. The multiplex MCDA-LFB assay detected wbgX at ≥1 pg/μL and ipaH at ≥10 fg/μL within 30 min in pure cultures maintained at 63°C. This assay was sensitive for ~37 CFU of virulent S. sonnei and ~3.7 CFU of Shigella spp. and enteroinvasive E. coli in stimulated fecal samples and had 100% specificity among 59 reference strains. The MCDA-LFB assay was also able to differentiate between virulent S. sonnei and other Shigella spp. and enteroinvasive E. coli among 99 clinical isolates. In summary, a multiplex MCDA-LFB assay was developed for rapid, convenient, point-of-care, and accurate identification of virulent S. sonnei within 30 min and at a constant temperature without the need for expensive lab equipment.