AAB Medical Technologist Microbiology Complete Practice Exam 2026

Listeria monocytogenes is known to produce a positive result in the catalase test, which is a crucial biochemical test used to differentiate between various bacterial species. The catalase test involves adding hydrogen peroxide to a bacterial sample. If the bacteria produce the enzyme catalase, bubbles of oxygen will be generated as the hydrogen peroxide is broken down. Since Listeria monocytogenes is a catalase-positive organism, this test can be used effectively to identify it in a clinical laboratory setting.

In contrast, other tests listed do not apply to Listeria monocytogenes in the same manner. For instance, the coagulase test is typically associated with Staphylococcus aureus and would not yield a positive result for Listeria. Beta-lactamase production is a characteristic seen in some resistant bacteria, but Listeria does not predominantly produce beta-lactamase. Lastly, the lactose fermentation test is typically used for differentiating lactose fermenters from non-fermenters, and Listeria monocytogenes is generally not a lactose fermenter on media like MacConkey agar, where it appears clear. Thus, the positive result in the catalase test is the key characteristic that helps in identifying Listeria monoc