Which of the following biochemical tests is negative for Listeria monocytogenes?

Listeria monocytogenes is a significant pathogen that can cause foodborne illness, and its biochemical characteristics are essential in laboratory identification. Among the various biochemical tests utilized to differentiate bacterial species, the coagulase test plays a vital role primarily when identifying Staphylococcus species, specifically Staphylococcus aureus, which is coagulase-positive.

Listeria monocytogenes, on the other hand, is coagulase-negative. This characteristic is valuable for microbiologists as it helps to exclude Listeria when identifying staphylococcal species. The fact that Listeria species are generally catalase-positive and oxidase-negative further solidifies the distinction from other bacterial genera.

In addition, Listeria monocytogenes does not ferment lactose, which serves as another crucial identifying factor. However, the other biochemical tests mentioned—catalase and oxidase—do not specifically focus on Listeria but rather help demonstrate its positive catalase reaction and negative oxidase reaction that align with its biochemical profile.

Therefore, the negative result of the coagulase test clearly identifies Listeria monocytogenes since it distinguishes it from coagulase-positive organisms, underscoring the relevance of this test in microbiological identification.