Tuberculosis

Question 1

What is tuberculosis?

Answer 1

It is a chronic granulomatous systemic disease caused by mycobacterium tuberculosis. This is a slow growing bacteria

Question 2

What are the risk factors for tuberculosis?

Answer 2

• 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

Question 3

Describe features of the disease course of tuberculosis and the spread?

Answer 3

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

Question 4

Describe features of primary tuberculosis

Answer 4

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.

Question 5

Describe features of secondary TB

Answer 5

• 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

Question 6

What is the general presentation of TB?

Answer 6

Symptoms depend onsite but usually accompanied by: night sweats, fever, weight loss and other systemic symptoms

Question 7

What is the pulmonary presentation of TB

Answer 7

• 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)

Question 8

What is the CNS presentation of tuberculosis?

Answer 8

• Headaches,
• Meningism,
• Focal neurological signs (cranial nerve lesions due to involvement of basal meninges)
• Decreased consciousness
• Serious complication of TB which has poor outcomes.

Question 9

What is the genitourinary presentation of TB

Answer 9

• Second most common area affected
• Presents with: Sterile pyuria, abscesses, salpingitis, infertility, epididymo-orchitis, renal pathology.

Question 10

What is the MSK presentation of TB

Answer 10

• Arthritis,
• Osteomyelitis
• Psoas abscess
• Pott’s disease of the spine

Question 11

What is the cardiac presentation of TB?

Answer 11

• Pericardial effusions
• Constrictive pericarditis

Question 12

Explain the lymph node and cutaneous presentation of TB

Answer 12

• May get lymphadenopathy which can progress to scrofuloderma (suppurative lymph nodes)
• Wide range of skin reactions including erythema nodosum and Bazin’s disease

Question 13

What are the investigations for TB

Answer 13

• 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

Question 14

What method screen for tuberculosis/ latent disease?

Answer 14

Mantoux test or interferon-gamma release assay

Question 15

What is the treatment for latent TB?

Answer 15

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

Question 16

What is the treatment for active TB?

Answer 16

6 month treatment - 2 RIPE/4 RI
- Intensive phase for 2 months with rifampicin, isoniazid, ethambutol and pyrazinamide.
- continuation for 4 months with rifampicin and isoniazid.

Question 17

What is the definition of multi drug resistant TB and how is it treated?

Answer 17

TB which is resistant to both rifampicin and isoniazid.
Treatment is 18-24 months of treatment with an 8 month intensive phase with the following drugs:
- Pyrazinamide
- Fluoroquinolones
- 2nd line injectable
- Ethionamide/prothionamide
- Cycloserine/p-aminosalicylic acid

Question 18

What are the side effects of Isoniazid?

Answer 18

Liver toxicity and peripheral neuropathy (pyridoxine/Vitamin B6 is given to prevent this) - N for numb

Question 19

What are the side effects of Rifampicin?

Answer 19

• Turns bodily fluids a red/orange colour
• p450 enzyme inducer
• Haemolysis
• Liver toxicity - hepatitis

Question 20

What are the side effects of Ethambutol?

Answer 20

• Optic neuritis (colour blindness, loss of acuity)
• Avoid in CKD

Question 21

What are the side effects of pyrazinamide?

Answer 21

Liver toxicity - hepatitis
Arthralgia
Hyperuricaemia - causes gout

Question 22

What else must you prescribe with TB treatment?

Answer 22

Pyridoxine (Vit B6) if giving isoniazid

Question 23

Describe features of mycobacterium tuberculosis

Answer 23

Weak gram positive bacterium with acid-alcohol fast bacilli
Slow growing in culture (6-8weeks) so molecular tests like Gene Xpert can identify TB directly from samples