Which of the following is a virulence test for Listeria monocytogenes?

The virulence test for Listeria monocytogenes is the Elek test, which is a laboratory method used to demonstrate the presence of specific virulence factors, particularly the production of the listeriolysin O (LLO) toxin. This test involves the use of a specific antisera that detects the toxin in a sample of Listeria monocytogenes. A positive result indicates that the strain is capable of causing disease due to its virulence factors.

While the Anton test, ELISA test, and Feeley-Gorman test have their uses in bacteriology, they are not specifically designed to assess the virulence of Listeria monocytogenes. The Anton test is primarily associated with the pathogenesis of Neisseria meningitidis and is not relevant here. The ELISA test is generally used for the detection of antibodies or antigens in various pathogens but does not specifically evaluate the virulence of Listeria. The Feeley-Gorman test was developed to isolate and identify Listeria, but it does not focus on its virulence characteristics. Thus, the correct identification of the Elek test emphasizes its critical role in determining the pathogenic potential of Listeria monocytogenes.