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 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 NTM 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 ?
Paucibacillary tuberculoid
- Few skin lesions
- robust Th1 cell response
Multibacillary lepromatous
- 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
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
which 2 tests are used to screen for TB ?
Tuberculin skin test
IGRA (interferon gamma release assay)
What are the first line medications to treat TB ?
RIPE
Rifampicin
Isoniazid
Pyrazinamide
Ethambutol
Which TB drug causes bright orange secretions ?
Rifampicin
What is the treatment schedule for pulmonary TB ?
- 6 months of Rifampicin and Isoniazid
- Pyrazinamide and Ethambutol for the first 2 months then stop
3 groups of tuberculosis mycobacteria
mycobacterium tuberculosis complex
mycobacterium avium complex
mycobacterium abscessus complex
features of non-tuberculous mycobacteria
atypical
resistant to the usual anti-TB therapy
slow growing = mycobacterium avium intracellular, mycobacterium marinum, mycobacterium ulcerans
rapid growing = m. abscessus, chelonae, fortuitum
what are the 2 types of mycobacterium leprae
pucibacillary tuberculoid - few skin lesions, robust T cell response
multibacillary lepromatous - abundance of bacilli, multiple skin lesions, poor T cell response
stages of TB infection
primary TB - usually asymptomatic
latent TB
reactivation of TB (>5yrs after initial infection), RF = immunosuppression, chronic alcohol excess, malnutrition, ageing
what does pulmonary TB cause
caseating granulomatas
found in upper lung parenchyma and mediastinal LN
what parts of the body are affected by extra-pulmonary TB
lymphadenitis
GI - swallowing of tubercules
peritoneal - ascitic or adhesive
genitourinary - slow progression to renal disease
bone + joint - haematogenous spread, spine (ports)
military TB
TB investigations
CXR sputum x3 bronchoscopy stains for acid-fast bacilli tuberculin skin test NAAT culture = gold standard, takes up to 6 weeks
what is the tuberculin skin test
looks for previous exposure to mycobacteria
2 units of tuberculin injected intradermaly
delayed-type hypersensitivity reaction
side effects fo RIPE
rifampicin - orange secretions
isoniazid - peripheral neuropathy, hepatotoxicty
pyrazinamide - hepatotoxicity
ethambutol - visual disturbance
what is given in extremely drug resistant TB
quinolones + aminoglycosides + para-aminosalicyclic acid + cycloserine + ethionamide
what is more likley to occur in HIV and TB
more likely to have extra-pulmonary manifestations
smear microscopy and culture is less sensitive
