Which of the following is NOT clinically used in the diagnosis of Tuberculosis?

The IgM Western Blot is not clinically used in the diagnosis of Tuberculosis. The reason this option stands out is that the Western Blot test is primarily used for detecting specific proteins and antibodies associated with certain infections, such as Lyme disease and HIV, but it does not have a role in the diagnosis of tuberculosis.

In contrast, the other options are well-established methods for diagnosing tuberculosis. Interferon Gamma Release Assays (IGRAs) and the Quantiferon Gold test are both blood tests that detect the immune response to specific TB antigens, thus indicating whether someone has been exposed to the bacteria that cause tuberculosis. The TB skin test, also known as the PPD test, involves an intradermal injection of purified protein derivative. A subsequent reading of the injection site helps to determine if there has been an immune response indicative of TB exposure.

Given the nature of the other testing methods directly related to tuberculosis, the distinction of the IgM Western Blot as irrelevant to TB diagnosis reinforces the understanding of appropriate diagnostic tools for this serious infectious disease.