The Voges-Proskauer (VP) test is used to identify organisms that can produce acetoin (acetylmethylcarbinol) as a byproduct of glucose fermentation.

This test is primarily used to differentiate between two closely related bacteria:

* *Enterobacter*: These bacteria are VP positive, meaning they produce acetoin.

* *Escherichia coli*: These bacteria are VP negative, meaning they do not produce acetoin.

However, the VP test can also be used to differentiate other bacteria based on their acetoin production.