Tuberculosis Flashcards
What is TB?
Pulmonary TB is an infectious disease caused by mycobacterium tuberculosis.
M.tuberculosis becomes dormant before it progresses to active TB.
It most commonly involves the lungs and is communicable in this form.
It may affect almost any organ system including the lymph nodes, CNS, liver, bones, GU tract and GI tract.
WHat should you do if pulmonary TB is made?
Patient should be isolated.
CXR should be obtained.
3 sputum samples should be collected for acid-fast bacilli smear and culture, and nucleic acid amplification test (NAAT) should be performed in of least 1 respiratory specimen.
Causes of TB
It required infection by M.tuberculosis and inadequate containment by the immune system.
Patients infected with no symptoms are said to have latent TB infection.
Active TB may occur from reactivation of latent TB or progression of primary infection.
Infection results from the inhalation of aerosolised droplets containing the bacterium.
Signs and symptoms of TB
Cough Fever Anorexia Weight loss Malaise Night sweats Pleuritic chest pain Haemoptysis Abnormal chest auscultation Dyspnoea Clubbing Erythema nodosum
Risk factors of TB
Exposure to infection Birth in an endemic country (Asia, Latin America, Eastern Europe or Africa) HIV infection Immunosuppressive medicine Silicosis Apical fibrosis Weak RF: Malignancy ESRD IV drug use Malnutrition Alcoholism Diabetes Low socio-economic status or black ancestry Age Tobacco smoking
Investigations of TB
CXR- abnormal typical for TB fibronodular opacities in upper lobes with or without cavitation. first-line test Sputum- Acid-fast bacilli smear positive Sputum culture- positive FBC- raised WBC, low Hb NAAT [positive] Consider: CT HIV test Tuberculin skin testing Bronchoscopy and bronchoalveolar lavage-positive for AFB
Differentials of TB
CAP Lung cancer Non-TB mycobacteria (NTM) Fungal infection Sarcoidosis
Management of TB
Combination- chemotherapy (including at least 2 drugs to which the bacterium is sensitive)
The reason for the combination is to:
Prevent resistance emergence
Reach a different bacterial population
Treatment of TB
Initial phase- 2 months
Isoniazid (300mg)
Rifampicin (450mg <50kg) (600 mg >50kg)
Pyrazinamide 1.5 g (<50 kg) (2g > 50kg)
Ethambulol 15 mg/kg
*Omit if low risk of isoniazid resistance
Continuation phase (4 months) (10 months if meningeal/CNS):
Isoniazid 300 mg
Rifampicin 450 mg (<50 kg) 600 mg (>50kg)
Side effects of Isoniazid
Hepatitis
Skin reactions
Peripheral neuropathy
Side effects of Rifampicin
Orange colour Hepatitis Skin reactions 'Flu' syndrome GI symptoms Thrombocytopenia
Side effects of Pyrazinamide
Hepatitis Flushing GI symptoms Arthralgia Hyperuricaemia Skin reactions
Side effects of Ethambulol
Retrobulbar neuritis
Arthralgia
Complications of TB
Death Site-specific damage: Lung (cavities, bronchiectasis, pleural thickening) Spine- paraplegia Brain- cranial nerve palsy, hemiparesis Amyloidosis (rare)
