Voges–Proskauer /ˈfoʊɡəs ˈprɒskaʊ.ər/ or VP is a test used to detect acetoin in a bacterial broth culture.
In the presence of oxygen and strong base, the acetylmethylcarbinol is oxidized to diacetyl, which then reacts with guanidine compounds commonly found in the peptone medium of the broth.
A reversal in the order of the reagents being added may result in a weak-positive or false-negative reaction.
[2] VP positive organisms include Enterobacter, Klebsiella, Serratia marcescens, Hafnia alvei, Vibrio cholerae biotype El Tor, and Vibrio alginolyticus.
[3] The reaction was developed by Daniel Wilhelm Otto Voges and Bernhard Proskauer, German bacteriologists in 1898 at the Institute for Infectious Diseases.