How the IGRA (QuantiFERON-TB Gold, T-SPOT.TB) works, how to run it, and how to read positive, negative, and indeterminate results, including why it is not affected by BCG.
What makes Mycobacterium unique: a waxy, mycolic-acid cell wall that makes these bacteria acid-fast, slow-growing, and hard to treat. An overview of tuberculosis, leprosy, and the...
How Mycobacterium tuberculosis causes tuberculosis: why it survives inside macrophages, how the granuloma leads to latent and active TB, the clinical picture, drug-resistant TB, an...
How the Mantoux tuberculin skin test works: the delayed-type hypersensitivity principle, how to place and read the induration, the 5/10/15 mm cutoffs and why they differ by risk gr...
How tuberculosis is diagnosed in the laboratory: the workflow from acid-fast smear to GeneXpert, culture on LJ medium, and drug-susceptibility testing, and how the tests fit togeth...
Löwenstein-Jensen (LJ) medium is the standard solid culture medium for Mycobacterium tuberculosis. Learn its principle, preparation by inspissation, colony characteristics of M. tu...
Semi-quantitative grades, probe-level RIF calls, error codes, and the traps: why a "RIF resistance detected" result still needs confirmation and why "not detected" never rules out...
Auramine-rhodamine is a WHO-recommended fluorochrome stain for detecting acid-fast bacilli, which is more sensitive than Ziehl-Neelsen and faster to screen. Learn the Truant method...
The non-tuberculous (atypical) mycobacteria: environmental organisms that cause lung disease, lymphadenitis, skin infections, and disseminated disease, how they differ from TB, and...
The hot ZN acid-fast staining method step by step, why mycolic acid holds carbol fuchsin against acid-alcohol, WHO smear grading from scanty to 3+, and what a negative smear does a...
Biochemical Tests to identify Mycobacteria, NTM
How Mycobacterium leprae causes leprosy, why the strength of cell-mediated immunity decides whether disease is tuberculoid or lepromatous, how it damages nerves, and how the slit-s...
