Tuberculosis Flashcards
What is the causative agent of tuberculosis?
Mycobacterium tuberculosis
What are the growth characteristics of Mycobacterium tuberculosis?
Obligate aerobe, slow-growing (doubling time of 15-20 hours)
Why can’t Mycobacterium tuberculosis be identified by the Gram stain?
Its wax-like and virtually impermeable cell wall requires a special staining technique called Ziehl-Neelsen.
What are the three essential macromolecules in the Mycobacterium tuberculosis cell wall?
Peptidoglycan
Arabinogalactan
Mycolic acids
How is Tuberculosis transmitted?
Transmitted via droplets over a prolonged time.
What is Tuberculosis?
A disease caused by Mycobacterium tuberculosis complex
What is the primary site of tuberculosis infection?
Primarily a pulmonary disorder, but it can cause systemic infection.
What are symptoms of TB in the lungs?
A bad cough lasting 3+ weeks
weight loss
blood in sputum
weakness
fatigue
fever
chills
night sweats.
What is the Bacille Calmette-Guerin (BCG) vaccine used for?
BCG is a partially effective vaccine for TB, offering some protection against severe forms of pediatric non-pulmonary TB.
What are the advantages of the acid-fast bacilli (AFB) test?
Accurate
simple
cheap
convenient.
What are the limitations of the acid-fast bacilli (AFB) test?
Cannot distinguish between live and dead bacteria, requires a high bacterial load, and cannot identify different species.
What conditions can Mycobacterium tuberculosis survive in during a latent infection?
Hypoxia, changes in redox, low nutrient levels, toxic fatty acids, acidic pH.
What is the method used in the tuberculin skin test?
Injection of Purified Protein Derivative (PPD) under the skin to detect antibodies indicating prior exposure to Mycobacterium tuberculosis.
Why is the diagnosis of TB by culture considered challenging?
It requires strong infrastructure, qualified staff, equipment, safety measures, and takes weeks for results.
