Tuberculosis (Microbiology) – Vocabulary Flashcards

A set of vocabulary flashcards covering key terms related to the microbiology, diagnosis, pathogenesis, treatment, and prevention of tuberculosis.

Mycobacterium tuberculosis

Acid-fast, non-motile, obligate aerobic, slender rod-shaped bacillus that causes tuberculosis.

Ziehl-Neelsen stain

Acid-fast staining technique used to visualize Mycobacterium tuberculosis in clinical specimens.

Mycolic acid

Long-chain fatty acid in the cell wall of M. tuberculosis that confers acid-fastness.

Lowenstein-Jensen (LJ) medium

Egg-based culture medium that is the gold standard for isolating M. tuberculosis.

CBNAAT (GeneXpert)

Rapid molecular test that detects M. tuberculosis DNA and rifampicin resistance.

Colony appearance on LJ medium

Rough, buff-colored, cauliflower-like colonies produced by M. tuberculosis.

Growth time of M. tuberculosis

Takes 4–8 weeks to form visible colonies on LJ medium.

Type IV hypersensitivity

Delayed-type, cell-mediated immune response central to tuberculosis pathogenesis and the Mantoux test.

Granulomatous response in TB

Lesion formed by activated macrophages and Th1 cells attempting to contain M. tuberculosis.

Ghon focus

Primary site of infection, usually in the mid-zone of the lung, produced by M. tuberculosis.

Ghon complex

Healed primary TB lesion consisting of a Ghon focus plus involved regional lymph nodes.

Atypical mycobacteria (NTM)

Environmental mycobacteria that cause opportunistic infections but not classical tuberculosis.

Examples of NTM

Mycobacterium avium and Mycobacterium kansasii.

Mantoux test

Intradermal injection of PPD to elicit delayed-type hypersensitivity indicating TB exposure.

Positive Mantoux criteria

10 mm induration in healthy individuals or >5 mm in immunocompromised persons after 48–72 h.

First-line anti-TB drugs

Isoniazid, rifampicin, pyrazinamide, and ethambutol.

MDR-TB

Multidrug-resistant tuberculosis; resistance to at least isoniazid and rifampicin.

XDR-TB

Extensively drug-resistant TB; MDR-TB plus resistance to any fluoroquinolone and a second-line injectable agent.

BCG vaccine

Live attenuated vaccine derived from Mycobacterium bovis.

Role of BCG vaccine

Prevents severe childhood forms of TB such as miliary tuberculosis and TB meningitis.

Tubercle bacillus

Another name for M. tuberculosis, distinguishing it from non-tuberculous mycobacteria.