Specificity: Specific to the LPS of Shigella flexneri 2a. No cross reactivity with: Shigella flexneri 1a, 3a, 4a, 5a, 6, Salmonellae (mix) and E. coli (mix), Salmonellae (mix) and Citrobacter. IS cross reactive with Plesiomonas shigelloides, as expected.