Second-Line Drug Susceptibility Testing (SL-DST) for Tuberculosis:Introduction, Principle, Procedure, Result-Interpretation, and Keynotes

Phenotypic drug susceptibility testing (DST) of Mycobacterium tuberculosis using the BACTEC MGIT 960 system

Introduction Second-line drug susceptibility testing (SL-DST) for tuberculosis is a crucial laboratory procedure designed to detect resistance to anti-TB drugs used when first-line treatment fails (i.e., multidrug-resistant TB – MDR-TB).  Principle SL-DST measures the susceptibility of Mycobacterium tuberculosis to specific agents by determining the Critical …

Read more

Xpert MTB/RIF: Introduction, Principle, Procedure, Result-Interpretation, Uses, and Keynotes

GeneXpert® Xpert® MTBRIF Test Result- MTB Detected (Very Low) and Rifampicin Resistance Not Detected

Introduction The Xpert MTB/RIF assay is an automated, cartridge-based molecular test used to detect Mycobacterium tuberculosis (MTB) and rifampicin (RIF) resistance, the most potent first-line anti-TB drug. Endorsed by the WHO in 2010, the Xpert MTB/RIF assay revolutionized TB diagnosis by providing results in less than two …

Read more

Xpert MTB/RIF Ultra: Introduction, Principle, Procedure, Result-Interpretation, Uses, and Keynotes

GeneXpert Dx System software interface displaying a completed diagnostic result for an Xpert MTB-RIF Ultra assay

Introduction Xpert MTB/RIF Ultra is an automated diagnostic test designed for the rapid and simultaneous detection of Mycobacterium tuberculosis (MTB) and resistance to rifampin (RIF). It is a second-generation assay developed by Cepheid to provide significantly higher sensitivity than the original Xpert MTB/RIF, particularly for …

Read more

Middlebrook 7H9 Broth: Introduction, Composition, Principle, Procedure, Result-Interpretation, Uses, and Keynotes

The BBL MGIT tube, showing Modified Middlebrook 7H9 Broth paired with an oxygen-sensitive fluorescent sensor for rapid diagnostic results

Introduction Middlebrook 7H9 broth is a liquid growth medium first described in 1958 by Middlebrook and Cohn for the specialized cultivation of Mycobacterium species. It is widely used in clinical and research settings for rapid growth, biochemical testing, and preparing inocula for drug susceptibility testing …

Read more