Agent in TB

Agent in TB

Learning Objectives

Explain about important factors of Mtb. that influences the TB epidemic.

Content

Mycobacterium tuberculosis (M. tuberculosis) belonging to the family Mycobacteriaceae cause Tuberculosis (TB).

These are rod shaped bacilli and require oxygen to survive (aerobic bacteria).

The following characteristics of these bacilli help them to survive in human body for a long time and resist the action of drugs:

Slow growing bacteria (replicates every 12-24 hours)
Tough, hydrophobic cell wall rich in mycolic acid that resists action of many drugs including antibiotics.
Ability to remain in dormant stage inside host tissues for many years in conditions with limited oxygen and nutrition (facultative anaerobes). They can revert to active state when favourable conditions (reduced host immune response, undernutrition etc.) ensue. The persistence of the bacteria in the host tissue for long duration of time is responsible for prolonged incubation period and re-activation of infection.
The multiple mechanisms of drug resistance by the bacteria give rise to multi-drug resistant and extensively drug-resistant tuberculosis.

These characteristics make tuberculosis a chronic granulomatous disease that requires special antibiotics for treatment.

Resources

Assessment

Question	Answer 1	Answer 2	Answer 3	Answer 4	Correct Answer	Correct Explanation	PageID	Part of pre-test	Part of post test
M. tuberculosis bacilli can survive conditions with limited oxygen. This means they are:	Strict aerobes	Strict anaerobes	Facultative anaerobes	None of the above	3	M. tuberculosis requires oxygen. However, they can survive in limited oxygen conditions also and can enter a dormant stage. They revert to active state when favourable conditions ensue. Thus, they are facultative anaerobes.		Yes	Yes

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