II-A. Systemic Bacteriology | 14. Mycobacterium tuberculosis and M. bovis

Question 1

I. Mycobacterium genus
1. What are the features of Mycobacterium genus

Answer 1

• aerobic rods
• Ziehl-Neelsen staining
• slow metabolism and proliferation!

Question 2

I. Mycobacterium genus
2. What is the staining for Mycobacterium genus?

Answer 2

can not be stained with Gram-staining (cell wall is special and too thick)
- we use Ziehl-Neelsen staining instead

Question 3

I. Mycobacterium genus
3. What are the feature of bacterial cell wall of Mycobacterium genus?

Answer 3

Bacterial cell wall contains specific components
- mycolic acid
- D-arabinan – D-galactan
- cord-factor (glycolipide with antiphagocyter properties)

Question 4

I. Mycobacterium genus
4. What are the important species of Mycobacterium genus?

Answer 4

• TB-group: M. tuberculosis, M. bovis, M. africanum
• non-TB group: M. avium, M. intracellulare, M. kansasi, M. marinum
• leprosy: M. leprae

Question 5

II. Mycobacterium tuberculosis
1. What is the source of infection of Mycobacterium tuberculosis?

Answer 5

source of infection: infected person

Question 6

II. Mycobacterium tuberculosis
1. What is the route of transmission of Mycobacterium?

Answer 6

usually via respiratory droplets

Question 7

II. Mycobacterium tuberculosis
3A. What are the feature of diseases caused by Mycobacterium tuberculosis?

Answer 7

diseases: usually affects the lungs primarily
- can proliferate intracellulary in the alveolar macrophages
- causes tissue necrosis, granulomas, cavities (usually found in upper or middle lobes)
- might disseminate via bloodstream / directly (especially in immunocompromised patients)

Question 8

II. Mycobacterium tuberculosis
3B. What are the symptoms of diseases caused by Mycobacterium tuberculosis?

Answer 8

• apetite loss, weight loss
• fatigue
• fever, night sweats
• chest pain, coughing
• sputum production

Question 9

II. Mycobacterium tuberculosis
4A. How do we diagnose Mycobacterium tuberculosis?

Answer 9

1. based on clinical signs and symptoms (difficult!)
2. tuberculin test (Mantoux-test or PPD-test)
3. sampling (multiple times!):
4. laboratory

Question 10

II. Mycobacterium tuberculosis
4B. How do we diagnose Mycobacterium tuberculosis based on sampling?

Answer 10

sampling (multiple times!):
* sputum, gastric aspirate
* blood (for quantiferon test)

Question 11

II. Mycobacterium tuberculosis
4C. How do we diagnose Mycobacterium tuberculosis based on laboratory?

Answer 11

1. Sputum: stained smear examination (ZN), culturing
   - it takes 6 to 8 weeks!
   - Löwenstein-Jensen medium
   +) enrichment on Midlebrook or Sula medium
2. blood: quantiferon test

Question 12

II. Mycobacterium tuberculosis
5A. What is the therapy for Mycobacterium tuberculosis?

Answer 12

Question 13

II. Mycobacterium tuberculosis
5B. What are the drugs we use for first line therapy?

Answer 13

• isoniazid (INH)
• rifampin (RIF)
• ethambutol (EMB)
• pyrazinamide (PZA)

Question 14

II. Mycobacterium tuberculosis
5C. What are the drugs we use for second line therapy?

Answer 14

• fluoroquinolones
• aminoglycosides

Question 15

II. Mycobacterium tuberculosis
6A. How do we prevent Mycobacterium tuberculosis

Answer 15

• BCG vaccine (Bacillus Calmette-Guerin)
• chemoprophylaxis

Question 16

II. Mycobacterium tuberculosis
6B. What are the features of BCG vaccine (Bacillus Calmette-Guerin)?

Answer 16

• contains live-attenuated M. bovis
• given to newborns (between 2-40 days)
• protects mainly against childhood infections (such as meningitis)
• less protective against adult’s pulmonary disease

Question 17

II. Mycobacterium tuberculosis
6C. How should we use chemoprophylaxis for Mycobacterium tuberculosis?

Answer 17

for close contacts of TB patients
* INH for months!

Question 18

III. What are the features of mycobacterium bovis?

Answer 18

• Infects cattle (cause of tb in cattle)
• Humans become infected by ingesting contaminated milk
• Enlarged caseous, cervical lymph nodes
• Used in the live, attenuated BCG vaccine against tb