A molecular test is currently available for rapid diagnosis of TB. The GeneXpert MTB/RIF assay simultaneously detects the DNA in M. tuberculosis and resistance to rifampin (RIF) in less than 2 hours. The information provided by this test aids in selecting treatment regimens and reaching infection control decisions quickly; however, the Xpert MTB/RIF assay does not replace the need for smear with microscopy for acid-fast bacilli, culture for mycobacteria, and growth-based drug susceptibility testing.2
2. Centers for Disease Control and Prevention. "A New Tool to Diagnose Tuberculosis: The Xpert MTB/RIF Assay." CDC.gov, https://www.cdc.gov/tb/publications/factsheets/pdf/xpertmtb-rifassayfactsheet_final.pdf. Accessed December 15, 2021.