Mycobacterial Diseases Flashcards
What percentage of the worlds population is infected with TB?
- 10%
- 25%
- 33%
- 50%
33%
Which of the following died of TB?
- John Keats
- George Orwell
- Frederic Chopin
- Eleanor Roosevelt
- Franz Kafka
All of them
The laboratory calls you saying they have found Acid Fast Bacilli in a clinical sample. Which answer is most appropriate?
- Ok, let’s see what the culture shows
- Thank them and recommend the start of TB therapy
- Exactly what kind of sample was this?
- Why are you calling me, I’m a medical student!
Thank them and recommend the start of TB therapy
How do we classify Tuberculoses
Describe the microbiology of TB
- Non-motile rod-shaped bacteria•
- Relatively slow-growing compared to other bacteria•
- Long-chain fatty (mycolic) acids, complex waxes & glycolipids in cell wall
- Structural rigidity
- Staining characteristics
- Acid alcohol fast
Label the image.
What stains do we use for acid alcohol fast bacilli
- Auramine
- Ziehl Neelsen
Where do non-tuberculous mycobacteria live?
Water and soil.
What are non-tuberculous mycobacteria
What are the slow growing NTM? Who do they affect? What are the associated with?
What are the fast growing NTM? Who do they affect? What are the associated with?
What is the epidemiology and RFs for infection with NTM?
Incidence on the rise! More prosthetic material in patients (catheters and cannula)
How do you diagnose infection with NTM?
How do you treat NTM?
What does mycobacterium leprae cause?
Very rare.
Describe mycobacterium tuberculosis. How common is it? Describe the epidemiology. How many cases have been reported?
Last year 4125 cases.
Heavily associated with HIV. Marker of AIDS.
A 23 year old male is a close contact of a person with smear positive pulmonary TB, What is his lifetime risk of developing active TB?
- 0.1%
- 1%
- 10%
- Don’t worry, be happy!
10%
What are the TB disease states?
- High endemic countries - early exposure
- When exposed:
- Macrophages see bug and recruit more macrophages to form granuloma → pathological signature of TB - keeps TB in check.
- When this occurs latent infection period
- Can reactivate the disease - active phase
Microbiology of MTB
How is MTB transmitted
How can we prevent TB?
Describe the natural history of TB.
What happen post-primary TB?
How does the host immune response shape clinical outcome.
Describe pulmonary TB.
Upper right lobe - worst perfused.
What are the extra-pulmonary manifestations of TB?
- Bone & joint
- Haematogenous spread
- Spinal TB most common
- Pott’s disease
- •Miliary TB
- Millet seeds on CXR
- Progressive disseminated haematogenous TB
- Increasing due to HIV•
- Tuberculous meningitis
What is the clinical approach to TB?
Describe the demographics and risk factors for TB
How does TB present?
What history and examination do you expect in TB?
What are the investigations for TB?
How do we diagnose TB?
How are smears used in TB diagnosis
What is the gold standard for diagnosing TB?
What does this show?
Histology TB
What additional tests can we do to diagnose TB?
Describe the Tuberculin skin test
Describe the use of Interferon gamma assays
What is this?
Mediastinal lymphadenopathy
What are the Anti-TB drugs?
How do we treat TB
- Duration
- 3 or 4 drugs for 2/12
- Then Rifampicin & Isoniazid 4/12
- 12/12 if CNS TB
- Cure rate 90%•
- Adherence
- Directly observed therapy (DOT)
- Video observed therapy (VOT)
Describe Multi-drug resistant TB
What are the challenges in diagnosing TB and HIV?
What are the WHO proposing in terms of tx for MDR-TB?
What are the challenges in treating HIV and TB?
