This test is used as a screening tool for tuberculosis (TB) which is caused by a bacterium Mycobacterium tuberculosis.
Tuberculosis Skin Test (PPD) – Mantoux Test
Category: Biochemical Tests
Biuret test
A biuret test is a chemical assay that helps check for the presence of protein in a given sample. To confirm the presence of protein, it will rely on the changes in color.
Ninhydrin Test
Ninhydrin is a chemical that detects ammonia and amines (primary and secondary). Once ninhydrin reacts with these chemicals, it produces an intense blue or purple color: Ruhemann purple.
Citrate Utilization Test
Citrate utilization can be used to distinguish between coliforms such as Enterobacter aerogenes (+ve) which occur naturally in the soil and in aquatic environments and fecal coliforms such as Escherichia coli (-ve) whose presence would be indicative of fecal contamination.
Voges Proskauer Test
It is a procedure that helps determine the microorganism’s ability to produce acetylmethyl carbinol, which is a neutral reacting end product.
Methyl Red Test
Methyl Red (MR) test is a biochemical test performed on bacterial species to detect the ability of an organism to produce stable acids end products (Mixed-acid fermentation) from supplied glucose.
Indole Test
Indole test is the a biochemical test performed on bacterial species to detect the ability of an organism to degrade the amino acid tryptophan and produce indole. It is used as the part of the IMViC tests, a set of four useful reactions that are commonly designed for the differentiation of enterics (members of family Enterobacteriaceae). The IMViC series includes following four tests Indole test Methyl red test Voges-Proskauer test Citrate test Principle of Indole Test Some […]
Urease Test
Urease test is a procedure used to find out the organism’s ability to split urea by producing an enzyme urease. Principle Decarboxylation of amino acids leads to the production of urea. Once urea undergoes hydrolysis, it produces ammonia and carbon dioxide. Urea is acidic but the formation of ammonia turns the medium into alkaline. The change in pH is indicated by the changes in color from light orange to magenta. Hence, an organism that tests […]
Oxidase Test
The oxidase test is used to identify bacteria that produce cytochrome c oxidase, an enzyme of the bacterial electron transport chain. When present, the cytochrome c oxidase oxidizes the reagent (tetramethyl-p-phenylenediamine) to (indophenols) purple color end product. When the enzyme is not present, the reagent remains reduced and is colorless. Purpose of Oxidase test Oxidase test is most helpful in screening colonies suspected of being one of the Enterobacteriaceae (all negative) and in identifying colonies suspected of belonging to other genera […]
Coagulase Test
Coagulase test is used to differentiate Staphylococcus aureus (positive) from Coagulase Negative Staphylococcus (CONS). Coagulase is an enzyme produced by S. aureus that converts (soluble) fibrinogen in plasma to (insoluble) fibrin. Staphylococcus aureus produces two forms of coagulase, bound and free. Slide coagulase test is done to detect bound coagulase or clumping factor. Tube coagulase test is done to detect free coagulase. Coagulation Test (Slide Method) Emulsify a staphylococcal colony in a drop of water […]
