Which of the following organisms is Voges-Proskauer positive?

The Voges-Proskauer test is a biochemical test used to detect the production of acetoin from glucose fermentation, which is a characteristic of some organisms. A positive result indicates that the microorganism can convert glucose into other compounds, including acetoin, which can be detected using α-naphthol and KOH in the test.

Enterobacter is known to be Voges-Proskauer positive, meaning it is capable of producing acetoin during fermentation, which can be detected by the test. This characteristic helps in its differentiation from other non-Voges-Proskauer positive organisms in microbiology, thus making it an important organism to recognize in a clinical setting.

In contrast, Shigella and Salmonella are generally Voges-Proskauer negative, indicating they do not produce acetoin from glucose fermentation. Citrobacter freundii has variable results with respect to this test; although it can sometimes be positive, it is often considered Voges-Proskauer negative as well. Understanding these distinctions is crucial for accurate microbial identification and diagnostic microbiology.