Development of a loop‐mediated isothermal amplification assay for molecular serotyping of Shigella flexneri Serotypes 2 and Xv

Aims This study developed and evaluated a loop‐mediated isothermal amplification (LAMP) assay to simply, rapidly and accurately identify Shigella flexneri serotypes 2 and Xv. Methods and Results The LAMP assay based on the O‐antigen synthesis and modification genes of S. flexneri including gtrII, gtrX, opt and wzx was developed. Its specificity and sensitivity were evaluated with 19 serotypes of S. flexneri and 96 other Shigella species and bacterial pathogens commonly found in stool samples. This LAMP assay was completed within 20 min at 61°C and could detect boiled DNA samples at concentrations as low as 1 pg/μl. The S. flexneri serotype LAMP assay exhibited 100% specificity for detecting 19 S. flexneri serotypes, no 96 strains of Shigella spp. and other bacterial pathogens. This LAMP assay was used to identify S. flexneri serotypes 2 and Xv from 299 S. flexneri strains isolated in China and results were consistent with that of slide agglutination and multiplex polymerase chain reaction results for the same isolates. Conclusions This LAMP assay may facilitate rapid and reliable identifying S. flexneri serotypes 2 and Xv. Significance and Impact of Study The present study was the first LAMP method for identifying serotypes of S. flexneri.