Which biochemical test is commonly performed to identify the presence of E. coli in clinical samples?

Which biochemical test is commonly performed to identify the presence of E. coli in clinical samples?

• A. Urease test
• B. Indole test
• C. Catalase test
• D. Oxidase test

Answer: (B)

The indole test is a biochemical test that specifically assesses the ability of an organism to hydrolyze tryptophan into indole, pyruvate, and ammonia through the action of the enzyme tryptophanase. Escherichia coli is known to produce indole, making this test a reliable method for its identification in clinical samples. When E. coli is present, the test results in a characteristic positive color change (typically red or pink) upon the addition of Kovac's reagent, indicating indole production. In the context of differentiating E. coli from other members of the Enterobacteriaceae family, the indole test plays a crucial role because not all Enterobacteriaceae are indole-positive. For instance, while Enterobacter and Klebsiella species are typically indole-negative, E. coli consistently shows a positive reaction. This distinct biochemical behavior makes the indole test a valuable tool in clinical diagnostics for identifying E. coli infections.

The indole test is a biochemical test that specifically assesses the ability of an organism to hydrolyze tryptophan into indole, pyruvate, and ammonia through the action of the enzyme tryptophanase. Escherichia coli is known to produce indole, making this test a reliable method for its identification in clinical samples. When E. coli is present, the test results in a characteristic positive color change (typically red or pink) upon the addition of Kovac's reagent, indicating indole production.

In the context of differentiating E. coli from other members of the Enterobacteriaceae family, the indole test plays a crucial role because not all Enterobacteriaceae are indole-positive. For instance, while Enterobacter and Klebsiella species are typically indole-negative, E. coli consistently shows a positive reaction. This distinct biochemical behavior makes the indole test a valuable tool in clinical diagnostics for identifying E. coli infections.