Respiratory Infections - Tuberculosis Flashcards
1
Q
What is TB?
A
- Airborne - caused by Mycobacterium tuberculosis
- Most people, once infected, don’t show symptoms.
2
Q
Describe airbone infection by TB.
A
- Once inhaled, travels to lungs - causes infection
- Between 2-12 weeks after infection, immune response limits multiplication of bacili
- Detected using positive tuberculin test
3
Q
Describe latent TB infections.
A
- TB not replicating and not infectious
- CXR normal
- Treatment for LTBI to prevent TB disease
- Skin/blood test result usually positive
4
Q
Describe TB disease.
A
- TB replicating and infectious
- Treatment required
- CXR abnormal
- Patient is sick
- Skin/blood test result - positive
5
Q
How is TB staged?
A
- Based on exposure time, severity, age, delay in diagnosis and endogenous factors
- EXAMPLES: Latent infection, cavitary and miliary TB
6
Q
What are the risk factors for TB exposure?
A
- Endemicity
- Gender, age, family size, climate
- Number of cases and case-contact interactions
- Duration of infection
7
Q
Describe MDR-TB and XDR-TB.
A
- Multi-drug resistant TB (MDR-TB) - resistant to isoniazid and rifampicin
- Extensively drug-resistant TB (XDR-TB) is MDR-TB - additional resistance to injectable agents/fluoroquinolones
8
Q
What are the three mechanisms leading to TB disease?
A
- Progression of primary infection to disease
- Endogenous reactivation of dormant bacili - due to decreased immunity
- Exogenous re-infection (further bacili inhalation)
9
Q
Why is the rate of TB and MDR-TB much higher in people who inject drugs?
A
- HIV co-infection
- Special needs regarding TB treatment adherence
10
Q
How is TB related to HIV?
A
- Strong mutual association
- HIV increases risk of progression from TB infection to disease
11
Q
What are the symptoms of TB?
A
- Cough > 2 weeks
- Low grade fever
- Weight loss
- Night sweats
12
Q
What should be paid attention to when screening for active TB disease?
A
- People with respiratory symptoms
- Household contacts of anyone with active case of pulmonary TB
- Coexisting risk factors (injecting drug use)
