Tuberculosis Flashcards
What is tuberculosis?
It is a chronic granulomatous systemic disease caused by mycobacterium tuberculosis. This is a slow growing bacteria
What are the risk factors for tuberculosis?
- Having lived in Asia, latin america, eastern europe or africa.
- Exposure to an infectious TB case
- Those living with HIV
- Immunocompromised patients (diabetes, immunosuppressive therapy, malnurished
- Silicosis
- Apical fibrosis
- Homeless
Describe features of the disease course of tuberculosis and the spread?
Spread by inhaling saliva droplets.
- Immediate clearance of bacteria
- Primary infection
- Latent tuberculosis (presence of bacteria without being contagious because immune system encapsulates bacteria)
- Secondary tuberculosis
- Miliary tuberculosis - disseminated and severe disease
Describe features of primary tuberculosis
Primary infection of lungs with small lesions called Ghon focuses and hilar lymphadenopathy (together is known as Ghon complex). In immunocompetent people this heals by fibrosis but in immunocompromised it can become miliary tb.
Describe features of secondary TB
- Occurs if the host becomes immunocompromised.
- Reactivation occurs in apex of lungs and spreads distally.
- Extra-pulmonary sites: CNS, vertebral bodies, cervical lymph nodes, renal and GI
What is the general presentation of TB?
Symptoms depend onsite but usually accompanied by: night sweats, fever, weight loss and other systemic symptoms
What is the pulmonary presentation of TB
- Most common presentation:
- Chronic cough productive of purulent sputum +/- haemoptysis
- Large cavity
- Bronchiectasis, pneumonia, fibrosis and pleural effusions
- Ghon complexes on x-ray (tubercle-laden macrophages and hilar lymphadenopathy)
What is the CNS presentation of tuberculosis?
- Headaches,
- Meningism,
- Focal neurological signs (cranial nerve lesions due to involvement of basal meninges)
- Decreased consciousness
- Serious complication of TB which has poor outcomes.
What is the genitourinary presentation of TB
- Second most common area affected
- Presents with: Sterile pyuria, abscesses, salpingitis, infertility, epididymo-orchitis, renal pathology.
What is the MSK presentation of TB
- Arthritis,
- Osteomyelitis
- Psoas abscess
- Pott’s disease of the spine
What is the cardiac presentation of TB?
- Pericardial effusions
- Constrictive pericarditis
Explain the lymph node and cutaneous presentation of TB
- May get lymphadenopathy which can progress to scrofuloderma (suppurative lymph nodes)
- Wide range of skin reactions including erythema nodosum and Bazin’s disease
What are the investigations for TB
- Chest X ray (upper lobe cavitation in reactivation, millet seeds in miliary tb)
- Sputum sample (3x early morning samples) to do acid-fast bacilli smear with direct visulisation using Ziehl-Neelsen stain
- Sputum culture Gold Standard (6 week wait) - can assess drug sensitivities, Mycobacterium blood cultures or lymph node biopsy
- NAAT testing
What method screen for tuberculosis/ latent disease?
Mantoux test or interferon-gamma release assay
What is the treatment for latent TB?
Isoniazid monotherapy for 6 months for adults and children (strongly recommended).
Rifampicin and isoniazid for daily 3 months as alternative for children/teens under 15.
Rifapentine and isoniazid weekly for 3 months as alternative for adults and children
