What is the most probable identification of a lactose-negative isolate that is indole positive and urease positive?

What is the most probable identification of a lactose-negative isolate that is indole positive and urease positive?

• A. Edwardsiella spp.
• B. Morganella spp.
• C. Ewingella spp.
• D. Shigella spp.

Answer: (B)

The correct identification of a lactose-negative isolate that is indole positive and urease positive is Morganella spp. This genus is known to produce urease and can test positive for indole, differentiating it from other lactose-negative members of the Enterobacteriaceae family. Morganella spp. are also characterized by their ability to metabolize certain amino acids, which contributes to the indole production observed in the test. Their urease positivity is a significant feature that aids in identification, especially in the context of differentiating it from other genera like Shigella, which would typically be urease negative and lactose negative. In contrast, other potential choices like Edwardsiella and Ewingella may share some biochemical characteristics with Morganella, but they do not consistently have the same urease and indole positivity pattern that defines Morganella spp. Shigella, on the other hand, is well-known for being lactose-negative and indole negative, making it an unlikely candidate for identification with the given biochemical tests. Thus, given the biochemical profile of indole positive and urease positive from a lactose-negative isolate, Morganella spp. is the most suitable identification in this case.

The correct identification of a lactose-negative isolate that is indole positive and urease positive is Morganella spp. This genus is known to produce urease and can test positive for indole, differentiating it from other lactose-negative members of the Enterobacteriaceae family.

Morganella spp. are also characterized by their ability to metabolize certain amino acids, which contributes to the indole production observed in the test. Their urease positivity is a significant feature that aids in identification, especially in the context of differentiating it from other genera like Shigella, which would typically be urease negative and lactose negative.

In contrast, other potential choices like Edwardsiella and Ewingella may share some biochemical characteristics with Morganella, but they do not consistently have the same urease and indole positivity pattern that defines Morganella spp. Shigella, on the other hand, is well-known for being lactose-negative and indole negative, making it an unlikely candidate for identification with the given biochemical tests.

Thus, given the biochemical profile of indole positive and urease positive from a lactose-negative isolate, Morganella spp. is the most suitable identification in this case.