The gold standard for diagnosis is culture using a Mycobacteria growth indicator tube (MGIT). For diagnostic purposes and further susceptibility testing, a test is performed to isolate M. tb in pure culture. The clinician may choose to conduct further susceptibility testing using LPA, MGIT, or NGS using the pure culture. WHO still advises using MGIT susceptibility test results to validate findings from LPA & NGS despite their lengthy turnaround time (up to 22 days).

Before the test, no preparation is required. However, it is suggested that you take the exam in the morning, ideally before breakfast.

In order to expectorate sputum during the MGIT test, the patient will be instructed to rinse their mouth with clean water first. The goal is to get lower respiratory tract secretions that are uncontaminated by sputum. A screw-capped jar will be used to collect the sputum sample.

An MPT64-specific monoclonal antibody is used in the lateral-flow immunochromatographic TBc ID test to detect MPB64 in liquid cultures. M. tuberculosis and some strains of M. produce the mycobacterial protein MPB64.