Haemophilus influenzae is a gram-negative bacterium that can cause infections such as meningitis, pneumonia, and septicemia. It is a major cause of illness in young children and can also infect adults with weakened immune systems. The diagnosis of H. influenzae infections requires biochemical tests to confirm the presence of the bacterium.
The identification of H. influenzae requires several biochemical tests, including the oxidase test, the catalase test, and the coagulase test. The oxidase test is used to determine if the bacterium produces cytochrome oxidase, which is an enzyme that is necessary for respiration. The catalase test is used to determine if the bacterium produces the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. The coagulase test is used to determine if the bacterium produces the enzyme coagulase, which is responsible for blood clotting.
The oxidase test is performed by placing a sample of the bacterium on a filter paper containing a reagent called tetramethyl-p-phenylenediamine dihydrochloride. If the bacterium produces cytochrome oxidase, the reagent will turn purple within 10 seconds.
The catalase test is performed by placing a small amount of the bacterium on a glass slide and adding a drop of hydrogen peroxide. If the bacterium produces catalase, the hydrogen peroxide will bubble and produce oxygen gas.
The coagulase test is performed by mixing a small amount of the bacterium with rabbit plasma. If the bacterium produces coagulase, the plasma will clot within a few minutes.
The biochemical tests for H. influenzae are essential for the diagnosis of infections caused by this bacterium. The oxidase test, catalase test, and coagulase test are commonly used to identify H. influenzae and distinguish it from other bacteria. These tests are simple and reliable, and they can be performed in any laboratory that has the necessary equipment.