Oxidasa positiva is a type of immunological test where a sample of a patient's blood or other body fluid is tested for the presence of an enzyme called oxidase. This test is used to diagnose and monitor a variety of bacterial, viral, and fungal infections and other conditions that affect the body's immune system. Oxidase is an enzyme found in bacteria and other microorganisms that helps them to break down organic compounds for energy. In the oxidase test, a laboratory technician adds a special reagent to the sample that reacts with oxidase and produces a color change if the enzyme is present. The different colors produced can indicate the presence of a particular type of microorganism, which then can be identified and further examined for the exact type and nature of infection.