MTB 2025

Question 1 Which characteristic is responsible for mycobacteria being strongly acid-fast when stained?

• A. Being obligate aerobic bacilli

• B. The presence of mycolic acid

• C. Serpentine cord forms on media

• D. Facultative intracellular growth

Question 2 What is the approximate slow generation time of mycobacteria, which helps prevent immune recognition?

• A. 6 hours

• B. 12 hours

• C. 18 hours

• D. 24 hours

Question 3 Which major virulence factor of M. tuberculosis is described as trehalose-6,6”-dimycolate?

• A. Muramyl dipeptide

• B. Wax D

• C. Lipoarabinomannan (LAM)

• D. Cord factor

Question 4 According to the pathogenesis of Tuberculosis, what event occurs in Stage V after caseous tubercles liquefy?

• A. T lymphocytes begin to infiltrate

• B. Spread of MTB into airways and other parts of the lung

• C. Primary infection of non-immune alveolar macrophages

• D. T-cell activation and liberation of gamma interferon

Question 5 Which of the following is a clinical feature associated with pulmonary tuberculosis infection?

• A. Acute cough

• B. Hemoptysis

• C. Hypertension

• D. Hyperthermia

Question 6 Which chemical agent is used in the laboratory to liquefy non-sterile specimens for decontamination prior to mycobacteria examination?

• A. 2% NaOH

• B. Malachite green

• C. N-acetyl-L-cysteine (NALC)

• D. Carbolfuchsin

Question 7 In the Ziehl-Neelsen staining technique, what color do non-acid-fast bacteria stain due to the counterstain?

• A. Red

• B. Green

• C. Yellow-green

• D. Blue

Question 8 Which stain utilizes Tergitol as a mordant (wetting agent/surfactant) and is performed without steaming?

• A. Ziehl-Neelsen technique

• B. Kinyoun stain

• C. Fluoroescence stain

• D. Gram stain

Question 9 According to the WHO reading interpretation for Ziehl-Neelsen stain, a result of 2+ indicates the presence of how many acid fast bacilli (AFB) per field?

• A. 1–9 AFB/100 fields

• B. 10–99 AFB/100 fields

• C. 1–10 AFB per field in at least 50 fields

• D. More than 10 AFB per field in at least 20 fields

Question 10 In the Runyon classification system based on pigment production, mycobacteria that produce pigment only when grown in the light are categorized as:

• A. Scotochromogens

• B. Rapid growers

• C. Non-chromogens

• D. Photochromogens