Tuberculosis

Question 1

Causative organism(s) in TB + Gram-/+?

Answer 1

Mycobacterium tuberculosis

• also caused by M. bovine and M. africanum
• these are all Gram-positive (mycobacterium family)

Question 2

Presentation of TB? (technically post-primary pulmonary TB)

Answer 2

Subacute illness including:

• cough
• haemoptysis
• dyspnoea
• fever
• night sweats
• anorexia

Question 3

CXR finding crucial to TB?

Answer 3

Lesions in the UPPER LOBE

Question 4

Features of extrapulmonary TB?

Answer 4

Painless lymphadenopathy
Constrictive pericarditis
Ascites
Spinal disease
Septic arthritis
Kidney infection

Question 5

Diagnosis of TB?

Answer 5

Sputum staining + culture

Question 6

Screening tests for TB?

Answer 6

Skin tuberculin testing

• Heaf test - multi-puncture method, read after 5 days, positive with ring-shaped induration
• Mantoux test - intradermal tuberculin injection, read at 3 days, positive with induration >5mm

Question 7

Conditions causing false negative in tuberculin screening?

Answer 7

Severe TB
HIV
Malnutrition
Malignancy
Sarcoidosis
Immunosuppressed patients

Question 8

Treatment of TB?

Answer 8

6 months of antituberculous therapy
- rifampicin + isoniazid + pyrazinamide + ethambutol 4 months
- rifampicin + isoniazid 2 months
Treatment given for 12 months for CNS disease

Question 9

What is multidrug-resistant TB (MDRTB) and how is it treated?

Answer 9

A TB infection that is resistant to rifampicin and isoniazid

• treated with 5 drugs for 24 months
• includes clarithromycin and streptomycin
• single dose before breakfast

Question 10

Side effects of commonly used antituberculous drugs?

Answer 10

Rifampicin - orange urine, purple tears, hepatitis, induced liver enzymes
Isoniazid - hepatitis, peripheral neuropathy
Pyrazinamide - hepatitis, photosensitivity, gout
Ethambutol - optic neuritis
Streptomycin - ototoxic, nephrotoxic