Evaluation of the Allplex^TM stx1/2/2a/2d Typing (ASTXT) assay for the diagnosis and typing of Shiga toxin-producing Escherichia coli

This study assessed the performance of the Allplex^TM stx1/2/2a/2d Typing (ASTXT) assay (Seegene) for diagnosis and typing Shiga toxin-producing Escherichia coli. Analytical sensitivity and specificity were evaluated using 18 spiked strains, and cross-reactivity was tested on 114 strains including E. coli without Shiga toxin. Clinical performance was evaluated using the proficiency panels and 76 stool samples. Analytical sensitivity was revealed to 4.14 log₁₀ CFU ml^-1 for E. coli strain with stx1, 4.47 log₁₀ CFU ml^-1 for strain with stx2, 4.03 log₁₀ CFU ml^-1 for strain with stx2a, and 4.02 log₁₀ CFU ml^-1 for strain with stx2d, respectively. Imprecisions were within 5 % and cross-reactivity was not observed. The ASTXT assay showed perfect agreement with the proficiency panel results and achieved 100 % positive and negative percent agreement using clinical stool samples. The ASTXT assay demonstrated reliable performance for the rapid detection and typing of Shiga toxin-producing E. coli in human stool samples.