Tuberculosis Flashcards
What stain is used to test for acid fast bacilli?
Ziehl-Neilson stain
In those with suspected TB, how are samples for microscopy and culture taking in patients who cannot produce sputum?
Bronchoscopy/bronchoalveolar lavage
What will histology of a lung biopsy of someone with TB show?
Caseating granulomas and acid fast bacilli
What is the standard treatment regimen for active TB?
2 months of rifampicin, isoniazid, pyrizinamide and ethambutol; 4 months of rifampicin and isoniazid
What is a fairly common side effect of many anti-TB drugs, and what is the best blood test to monitor for it?
Hepatitis- monitor LFTs
What are the two tests that can be used to screen for evidence of current/previous infection with TB?
Mantoux test, interferon gamma release blood tests
If the screening tests for TB are positive, what is the next investigation used to assess for evidence of active TB?
CXR
Describe how a Mantoux test can often cause false positives?
Those who have had the BCG
Describe how a Mantoux test can often cause false negatives?
Those with miliary TB
What are some common CXR findings of TB?
Upper lobe shadowing and cavitation; mediastinal lymph node enlargement
What is the most important microbiological test for TB?
Sputum sample for acid-fast bacilli and culture
How many samples of sputum should be taken for testing for acid-fast bacilli?
3 morning samples
On a CXR, the presence of what suggests primary TB?
Ghon complex, a ghon focus and hilar lymphadenopathy
On a CXR, the presence of what suggests secondary TB?
A fibrosing and cavitating apical lesion
TB most commonly presents as a history of systemic disturbance lasting how long?
Weeks-months (subacute)
Name the most common systemic features of TB?
Weight loss, fever, malaise and night sweats
What are the most common respiratory features of TB?
Cough and haemoptysis
What organism is responsible for the vast majority of cases of TB?
Mycoplasma tuberculosis
M. bovis is a rare cause of TB- how is it acquired?
Drinking infected cow’s milk
What is meant by the term miliary TB?
Active TB which is disseminated around the body via haematological spread
Multi-drug resistant TB describes TB which is resistant to which antibiotics?
Rifampicin and isoniazid
What are the chances that latent TB will progress to active TB?
5% risk of progression to active disease within two years of infection; 5% lifetime risk of reactivation thereafter
Where in the world is the incidence of TB highest?
Asia and sub-Saharan Africa
Name some high risk groups for TB infection?
Birth in high incidence countries, immunosuppresion, overcrowding/homelessness
