What lab test would differentiate shigella flexneri from yersinia pseudotuberculosis?

To differentiate Shigella flexneri from Yersinia pseudotuberculosis, a key lab test is the urease test. Yersinia pseudotuberculosis is urease positive, while Shigella flexneri is urease negative. Additionally, biochemical tests such as the fermentation of lactose can help, as Shigella flexneri does not ferment lactose, whereas Yersinia may show variable lactose fermentation.