II-A. Systemic Bacteriology | 14. Mycobacterium tuberculosis and M. bovis Flashcards
I. Mycobacterium genus
1. What are the features of Mycobacterium genus
- aerobic rods
- Ziehl-Neelsen staining
- slow metabolism and proliferation!
I. Mycobacterium genus
2. What is the staining for Mycobacterium genus?
can not be stained with Gram-staining (cell wall is special and too thick)
- we use Ziehl-Neelsen staining instead
I. Mycobacterium genus
3. What are the feature of bacterial cell wall of Mycobacterium genus?
Bacterial cell wall contains specific components
- mycolic acid
- D-arabinan – D-galactan
- cord-factor (glycolipide with antiphagocyter properties)
I. Mycobacterium genus
4. What are the important species of Mycobacterium genus?
- TB-group: M. tuberculosis, M. bovis, M. africanum
- non-TB group: M. avium, M. intracellulare, M. kansasi, M. marinum
- leprosy: M. leprae
II. Mycobacterium tuberculosis
1. What is the source of infection of Mycobacterium tuberculosis?
source of infection: infected person
II. Mycobacterium tuberculosis
1. What is the route of transmission of Mycobacterium?
usually via respiratory droplets
II. Mycobacterium tuberculosis
3A. What are the feature of diseases caused by Mycobacterium tuberculosis?
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)
II. Mycobacterium tuberculosis
3B. What are the symptoms of diseases caused by Mycobacterium tuberculosis?
- apetite loss, weight loss
- fatigue
- fever, night sweats
- chest pain, coughing
- sputum production
II. Mycobacterium tuberculosis
4A. How do we diagnose Mycobacterium tuberculosis?
- based on clinical signs and symptoms (difficult!)
- tuberculin test (Mantoux-test or PPD-test)
- sampling (multiple times!):
- laboratory
II. Mycobacterium tuberculosis
4B. How do we diagnose Mycobacterium tuberculosis based on sampling?
sampling (multiple times!):
* sputum, gastric aspirate
* blood (for quantiferon test)
II. Mycobacterium tuberculosis
4C. How do we diagnose Mycobacterium tuberculosis based on laboratory?
- Sputum: stained smear examination (ZN), culturing
- it takes 6 to 8 weeks!
- Löwenstein-Jensen medium
+) enrichment on Midlebrook or Sula medium - blood: quantiferon test
II. Mycobacterium tuberculosis
5A. What is the therapy for Mycobacterium tuberculosis?
II. Mycobacterium tuberculosis
5B. What are the drugs we use for first line therapy?
- isoniazid (INH)
- rifampin (RIF)
- ethambutol (EMB)
- pyrazinamide (PZA)
II. Mycobacterium tuberculosis
5C. What are the drugs we use for second line therapy?
- fluoroquinolones
- aminoglycosides
II. Mycobacterium tuberculosis
6A. How do we prevent Mycobacterium tuberculosis
- BCG vaccine (Bacillus Calmette-Guerin)
- chemoprophylaxis
II. Mycobacterium tuberculosis
6B. What are the features of BCG vaccine (Bacillus Calmette-Guerin)?
- 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
II. Mycobacterium tuberculosis
6C. How should we use chemoprophylaxis for Mycobacterium tuberculosis?
for close contacts of TB patients
* INH for months!
III. What are the features of mycobacterium bovis?
- 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