What organism is indicated by the reactions: Urease Negative, Phenylalanine deaminase Negative, Lysine decarboxylase Negative, Motility Negative, Citrate Negative?

The organism indicated by the stated reactions, which include urease negative, phenylalanine deaminase negative, lysine decarboxylase negative, motility negative, and citrate negative, aligns with the characteristics typically associated with Shigella dysenteriae.

Shigella dysenteriae is a non-motile, gram-negative bacillus that does not produce urease, does not have the capability to deaminate phenylalanine, and does not decarboxylate lysine. Its inability to utilize citrate as a sole carbon source and its characteristic of being non-motile further support the identification of this organism.

In contrast, other options such as Escherichia coli and Salmonella typhimurium exhibit distinct reactions; for example, E. coli is typically urease positive or at least variable and motile, and Salmonella generally shows motility and may also be lysine positive. Klebsiella oxytoca is usually urease positive, motile when compared to Shigella, and can decarboxylate lysine, which also distances it from the described reactions.

Thus, the reaction profile of urease negative, phenylalanine deaminase negative, lys