Tuberculosis Flashcards
how does TB spread ?
through inhaling saliva droplets from someone with active infection
what is TB ?
an infection that commonly affects the lung.
can TB cause systemic symptoms ?
yes as it can infect other parts of the body
what bacteria causes TB?
mycobaterium turberculosis
why is TB bacteria described as ‘acid-fast bacilli’ ?
positive rod shaped bacteria (bacilli)
strict aerobes (requires oxygen)
has a waxy coating that is resistant to the acid in gram staining - ‘acid-fast’
what is a granuloma ?
collection of macrophages in response to inflammation
what do granulomas in TB contain ?
necrosis (dead cells) - ‘caseous necrosis’ / cheesy
What are the types of TB ?
Primary TB
Latent TB
Secondary TB
Active TB
Miliary TB
what is primary TB?
host develops a primary infection in the lungs
Is latent TB infectious and why ?
‘Ghons focus’ - not infectious
TB bacteria in encapsulated
what occurs in secondary TB?
latent TB becomes reactivated
what can secondary TB affect?
extrapulmonary sites
what is active TB?
when active infection occurs within various sites of the body
what are most TB cases?
secondary TB
what is miliary TB?
TB has haematogenous spread throughout the body.
What TB is life-threatning ?
mililary TB
what are risk factors for TB ?
people from south asia, southern africa etc.
immunosuppression - HIV, immunosuppressive drugs
people who have come in contact with active TB
what vaccine is used for TB?
BCG vaccine
- everyone at risk of TB
what test is required prior to TB vaccination ?
Mantoux test - needs to be negative
what are the main presentations of TB?
history of chronic, gradually worsening symptoms
night sweats
weight loss
fever
cough
what are the main investigations for TB?
CXR and sputum sample
Ziehl-neelson stain
what does ziehl-neelson stain show ?
turns TB bacteria bright red
what may you see on a CXR if TB is present ?
‘millet seeds’ - where miliary TB gets its name.
what drugs are used to treat TB?
RIPE
R - Rifamipicin
I - isoniazide
P - pyrazinamides
E - Ethambutol
what do you give for active TB ?
2 months of RIPE
followed by 4 months RI
what do you give for latent TB?
3 months of RI
OR Isoniazid for 6 months
what are common side effects of RIPE ?
Rifampicin = red/orange discolouration of secretions like urine and tears (red-pissing)
Isoniazid = peripheral neuropathy.
Pyrazinamide = hyperuricaemia (high uric acid levels) resulting in gout.
Ethambutol = colour blindness and reduced visual acuity.
what drugs are associated with hepatotoxicity ?
RIP
Rifampicin
Isoniazid
pyrazinamide
