Tuberculosis Flashcards
(21 cards)
What is TB?
A granulomatous disease caused by Mycobacterium tuberculosis.
How is TB transmitted?
By inhalation of affected droplets.
What is the global prevalence of TB?
1/3rd latent TB infection
‘2 bn’ (1/4)
1/5 of hiv deaths are due to TB
What are the physiological characteristics of primary TB?
In 90% of cases the immune system contains the infection, macrophages engulf the bacteria and localise them to the hilar lymph nodes. Here, they are either eliminated or encapsulated by granulation tissue (considered to be in a dormant state).
What happens in (secondary) active TB where the immune system can’t contain it?
Disease in apex of lungs, can spread through bloodstream (military tb)
What are the risk factors?
Ethnic minority (Africa and S. Asia) (risk higher if returned from high prevalence area in last 5 years)
The homeless
Drug and alcohol abuse
(The two above are associated with poor housing and malnutrition)
Close contact with infected patient (household members have 1/3rd risk)
Immunosuppression
Young or old age
What is the general presentation?
Night sweats
Fever
Weight loss
What is the pulmonary presentation?
Chronic cough with sputum and sometimes haemoptysis
Can get bronchiectasis, pneumonia and pe.
What are the neurological symptoms?
Headache
Meningism
Decreased consciousness
Meningitis
What is the second most affected system?
Génito-urinaires
What is the msk presentation?
Arthritis
Osteomyelitis
Psoas abscess
Potts disease
What is the GI presentation?
Abdominal pain
Appendicitis
What are is the pericardial presentation?
Pericarditis
Pericardial effusions
Dermatological presentation?
A wide range of skin infections including erythema nodosum and Bazin’s disease.
Investigations?
CXR - consolidation in Alice’s
Sputum samples at least 3 (8-24 hour gap) (may need induced)
Non pulmonary sample (biopsy, needle aspiration)
Bronchoscopy with BAL
EBUS with biopsy
Lumbar puncture in cns tb
Urine in urogénital tb
How is TB treated?
Isoniazid, rifampicin, ethambutol and pyrazinamide for 2 months, then isoniazid and rifampicin for a further 4 months.
Extended in TB meningitis, pericarditis
What are the side effects of Isoniazid?
Peripheral neuropathy (prevented with pyridoxine)
Hepatitis
Side effects of rifampicin?
Hepatitis
Hepatic enzyme (p450) inducer
Turns bodily fluids red/orange colour
Side effects of ethambutol?
Optic neuropathy
Avoid in chronic kidney disease
Side effects of pyrazinamide?
Liver toxicity
Gout
All four drugs can cause rash
How is latent TB screened?
Mantoux skin test or IGRA blood test
Treatment is rifampicin and isoniazid 3 months,
Or isoniazid or rifampicin only for 6 months or
Rifapentine and isoniazid once weekly for 12 weeks
