Which test is employed to differentiate Salmonella from Proteus species?

The urease test is used to differentiate Salmonella from Proteus species because of the distinct urease activity associated with Proteus. Proteus species can hydrolyze urea, leading to the production of ammonia, which raises the pH of the medium, resulting in a color change that indicates a positive urease test. In contrast, Salmonella species typically do not produce urease, thus yielding a negative result on this test. This method is particularly useful because both genera can be found in similar environments and may exhibit similar morphological characteristics, making the urease test a practical tool for identification.

The other tests, such as the catalase test, oxidase test, and coagulase test, are not reliable for this specific differentiation. The catalase test assesses whether an organism produces the enzyme catalase, which breaks down hydrogen peroxide, and is not specific enough to distinguish between the two. The oxidase test is used to determine the presence of cytochrome c oxidase, but again, it does not differentiate between Salmonella and Proteus effectively. The coagulase test is primarily used for identifying Staphylococcus species, particularly Staphylococcus aureus, and is not relevant in this context. Therefore, the urease test is the