10. TB Flashcards
What are the risk factors for TB?
Endemic areas History of TB or exposure HIV/AIDS or immunosuppression Overcrowding Drug use, homelessness TNF inhibitors
How is TB spread?
Droplets
What factors in a history cause a suspicion of TB?
Cough that has lasted weeks to months, not responding to antibiotics
Haemoptysis
Spiking fever
Night sweats and weight loss
What signs can be seen in TB?
Clubbing
Monoarthropathy
Erythema nodosum
Scrufuloderma
What is a scrufuloderma?
Skin lesions from underlying TB in a lymph node, bone or joint
What other diseases are included in the differential for TB?
Lung cancer
Sarcoidosis
Lymphoma
What is the spectrum of disease caused by TB?
Pulmonary Pleural Extra-pulmonary Meningeal Miliary
Which form of TB produced a very strong antimicrobial response?
Pleural
What are common sites of extra-pulmonary TB?
Bone
Kidneys
Skin
What investigations should be done into TB?
Sputum for ZN stain and culture or PCR for rapid diagnosis
CXR
Mantoux test
What does a positive smear and culture of TB mean?
Very infective
What does a negative smear but positive culture mean?
Latent TB
What does a positive smear and negative culture mean?
Treatment is working as the bacteria are dead
Why does TB often infect the upper lobes of the lung?
High V/Q ratio: brought in on high airflow and not cleared due to lower blood flow
What does a 5mm Mantoux test mean?
Positive in HIV and recent contacts
What does a 10mm Mantoux test mean?
Positive in moderate risk (travel, IVDU)
What does a 15mm Mantoux test mean?
Positive in no known risk factor
What is measured in the Mantoux test?
Elevation
What causes a false positive Mantoux test?
Other mycobacterial infection
BCG vaccine
What causes a false negative Mantoux test?
Anergy Recent TB infection Very young Live-virus vaccine Overwhelming TB
What is the treatment for pulmonary TB?
Isoniazid, rifampicin, pyrazinamide and ethambutol for 2 months
Isoniazid and rifampicin for 4 months
What is the treatment for neuro and miliary TB and why is it given?
Corticosteroids: dampen the immune response to dead TB
How long is the course of antibiotics for extra-pulmonary TB?
9-12 months
What are the side effects of isoniazid?
Hepatotoxicity
Peripheral neuropathy
What is given to prevent peripheral neuropathy in isoniazid treatment?
Pyridoxine (vit B6)
What are the side effects of rifampicin?
Hepatotoxicity
Turns secretions orange
What are the side effects of ethambutol?
Optic neuritis
What are the side effects of pyrazinamide?
Hepatotoxicity
What TDM is done for a patient being treated for TB?
Monitor pre-treatment LFTs and 2 weeks after starting
Drugs should be discontinued if transaminases are >5 times normal
Drugs reintroduced individually and sequentially
Define multi-drug resistant TB
Resistant to isoniazid and rifampicin
Define extremely drug resistant TB
Resistant to isoniazid, rifampicin and 3+ classes of second line agents
How is latent TB diagnosed?
Mantoux test
IGRA
What is the treatment for latent TB?
- isoniazid for 9/12
- rifampicin for 4/12
- rifapentine and isoniazid for 3/12
What is the difficultly in treating someone with TB and HIV?
Interactions between HAART and anti-TB drugs
What is the BCG vaccine effective in preventing?
Childhood miliary TB and TB meningitis
