Microbiology 13: Mycobacterial Diseases Flashcards
Which organism is used in the BCG vaccine ?
Mycobacterium. Bovis
Describe Mycobacterium as an organism ?
Non-motile
Rod shaped
Waxy cell wall
Slow-growing compared to other bacteria
Acid alcohol fast
gram +ve
Name 2 stains that pick up mycobacterium ?
auramine
Ziehl neelson
Name the slow growing NTM that causes swimming pool granuloma ?
Mycobacterium Marinum
Which slow growing NTM causes Buruli ulcers ?
Mycobacterium Ulcerans
What are some risk factors for Non-Tuberculous Mycobacteria infections ?
Age
Underlying lung disease- CF, Bronchiectasis, COPD
Immunocompromised
What are the 2 types of mycobacterium leprae?
- Paucibacillary tuberculoid
- Multibacillary lepromatous
What are the main differences between Paucibacillary tuberculoid and Multibacillary lepromatous ? NB both types of Mycobacterium Leprae
Paucibacillary tuberculoid
- LOW in bacterial cells
- Few skin lesions
- robust Th1 cell response
Multibacillary lepromatous
- MASSIVE AMOUNT of bacterial cells
- abundance of bacilli
- multiple skin lesions
- Poor Th2 mediated cell response
What is the primary TB granuloma in the lungs called ?
Ghon focus
Which allergic reaction can be seen with primary TB ?
Erythema nodosum
What is TB infection of the spine called ?
Pott’s disease
Which bone is mainly affected in TB?
Spine - particularly affects the thoracic spine
Can get Pott’s disease
What is Scrofula ?
Lymphadenitis due to TB, usually affecting the cervical lymph nodes.
How can you test for TB in children ?
Gastric aspirate- children swallow their sputum
What are the first line medications to treat TB ?
RIPE
For 6 months
- Rifampicin
- Isoniazid
For the first 2 months only
- Pyrazinamide
- Ethambutol
Which TB drug causes bright orange secretions ?
Rifampicin
What must you give on top of the 4 pulmonary TB meds and why?
- pyridoxine (Vitamin B6)
- since isoniazid can cause peripheral neuropathy otherwise
What percentage of the world’s population are infected with TB?
- 33%
What is the Most common opportunistic infection in HIV
TB
Which infectious agent is the most common cause of death worldwide
TB
2 classifications of post-primary TB infection
- Pulmonary
- Extra-pulmonary
Key pathalogical feature of pulmonary TB and where it is most commonly found
- caseating granuloma (involves lots of dead necrotic macrophages with bacteria in it)
- R upper lobe most commonly
Ix for miliary TB
Why has incidence of this type of TB increased?
- CXR: see millet seeds
- Increased due to HIV
Order of stains done for ACTIVE TB
Tests for LATENT TB infection
Active:
- Auramine first (will fluoresce if +ve)
- If +ve, then do Ziehl-Neelsen
Latent:
- Tuberculin skin test
- IFNg release assays (used far more in UK)
