Questions on tuberculosis
Definition and classification
- What is tuberculosis? H
- What are the types of tuberculosis? Hl
- What is Ghon’s complex? Hl
- What is Ghon’s focus? Hl
- What is FDC? Hl
- Define new case, relapse, treatment failure, treatment after default, and chronic TB? Hl
- What are the types of drug resistant tuberculosis? hl
Epidemiology
- Why do we give BCG vaccine? Hl
- How much protection can give BCG vaccine? Hl
- How do we prevent TB? hl
Etiology and Pathophysiology
- What are the organisms causing tuberculosis? Hl
- Tell another mycobacterium other than tuberculosis. Hl
- Why is mycobacterium called acid or alcohol fast? H
- What are the sources of infection? Hl
- What are the routes of entry? Hl
- What are the sites of primary tuberculosis? Hl
- What are the common sites of pulmonary TB? Hl
- What are the sites of extrapulmonary TB? Hl
- What are the organs resistant to develop TB? hl
Clinical manifestations
- What are the clinical features of pulmonary tuberculosis? hl
Examinations
- Q
Investigations
- What investigations are done to diagnose pulmonary TB? Hl
- Which test gives rapid diagnosis? hl
- What are the radiological presentations/findings of pulmonary tuberculosis? Hl
- What type of opacity is found in chest X-ray of a pulmonary TB patient? hl
- What are the histological findings in tubercular lesions? Hl
- How will you investigate a case of sputum positive pulmonary TB during treatment? hl
Diagnosis
- Why do you think this is pulmonary TB? hl
- Which type of pulmonary TB do you think and why? Hl
- Why is this not bronchiectasis? hl
- Why is this not bronchial carcinoma? Hl
Treatment
- What are the aims of treatment of tuberculosis? Hl
- What is category-I treatment? hl
- What are the indications of category-I? hl
- What is the basis of combination therapy? Hl
- Why multidrug treatment is rational? Hl
- What are the advantages of fixed drug combinations (FDC)? Hl
- Why long-term treatment is required? Hl
- What are the drugs used in TB? Hl
- What is the treatment plan of TB according to national tuberculosis program (NTP)? Hl
- What is 6 months regimen? Hl
- Name a single side effect from each of the 1st line anti-TB drugs? Hl
- How can you assess response to anti-TB treatment? hl
Complications
- A patient on anti-TB suddenly developed jaundice, how will you manage the patient? hl
Rimikri
SOLVES
What is tuberculosis?
It is a chronic specific systemic infectious disease caused by Mycobacterium tuberculosis complex.
* Pre-exam preparation for medicine, HN Sarker
What are the types of tuberculosis?
According to site:
- Pulmonary tuberculosis
- Primary
- Postprimary
- Reactivation
- Reinfection
- Extrapulmonary tuberculosis
- Outside the lung parenchyma (according to USA)
- Outside the lung and pleura (according to UK).
According to bacteriological specimen
- Smear positive
- 2 sputum positive for AFB
- 1 sputum positive with chest X-ray abnormality
- 1 sputum positive with one culture positive.
- Smear negative
- Symptoms suggestive of tuberculosis with 3 negative sputum specimens
- Persisting symptoms after a course of antibiotics
- 3 negative sputum specimen or repeated X-ray negative
According to treatment category
- Category 1
- Category 2.
* Pre-exam preparation for medicine, HN Sarker
What is Ghon’s complex?
A combination of
- Ghon’s focus,
- hilar lymphadenopathy and
- lymphangitis.
* Pre-exam preparation for medicine, HN Sarker
What is Ghon’s focus?
The formation of a granuloma surrounding an area of caseation leads to the appearance of primary lesion in the lung is known as Ghon’s focus.
* Pre-exam preparation for medicine, HN Sarker
What is FDC?
FDC means fixed dose combination, i.e. drugs are present in fixed amount in single tablet.
* Pre-exam preparation for medicine, HN Sarker
Define new case, relapse, treatment failure, treatment after default, and chronic TB?
New case: A patient who has never taken anti TB or taken for less than 1 month.
Relapse: A patient who recently received treatment and was cured or treatment completed and now again developed smear positive pulmonary TB.
Treatment failure: A patient while on management remain smear positive or becomes smear positive at 5 months or more after start of management or a patient who was initially smear negative and is found smear positive at the end of 2nd month of treatment.
Treatment after default: A patient who completed at least 1 month of treatment and returned after at least 2 months after interruption of treatment.
Chronic: A patient who remained smear positive after completing directly observed retreatment regimen.
* Pre-exam preparation for medicine, HN Sarker
What are the types of drug resistant tuberculosis?
- Primary drug resistance: It occurs in those exposed to others infected with resistant organism.
- Secondary drug resistance: Occurs in patients who do not comply with the treatment regimen.
- Multidrug resistance: Resistance to INH + rifampicin with or without other drug resistance.
- XDRTB: Resistance to rifampicin +INH and any member of the quinolone and at least any of the injectable 2nd line drug.
* Pre-exam preparation for medicine, HN Sarker
Why do we give BCG vaccine?
Causes of giving BCG (bacille Calmette–Guérin) vaccine are:
- Protection against tubercular meningitis and military tuberculosis.
- To protect the babies from TB which may be transmitted from mother or other source.
- Lack of maternal antibody against TB. The earlier the age, the higher the protection.
* Pre-exam preparation for medicine, HN Sarker
How much protection can give BCG vaccine?
Protections are:
- BCG gives protection upto 7 years
- Protect in young 0%–70%.
* Pre-exam preparation for medicine, HN Sarker
How do we prevent TB?
Prevention of TB:
- General health promotion
- Effective treatment of sputum positive case
- Specific protection
- Active immunization
- Chemoprophylaxis—INH 5 mg/kg/day for 9 months.
* Pre-exam preparation for medicine, HN Sarker
What are the organisms causing tuberculosis?
The organisms are:
- Mycobacterium tuberculosis
- Mycobacterium bovis
- Atypical mycobacteria, e.g.
- M. kansasii ,
- M. marinum, and
- M. avium intracellulare complex .
* Pre-exam preparation for medicine, HN Sarker
Tell another mycobacterium other than tuberculosis.
Mycobacterium leprae causing leprosy.
* Pre-exam preparation for medicine, HN Sarker
Why is mycobacterium called acid or alcohol fast?
Mycobacterium is called acid or alcohol fast because it resists decolorization with acid and alkali.
* Pre-exam preparation for medicine, HN Sarker
What are the sources of infection?
The sources of infection are:
- Human source
- Bovine source.
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What are the routes of entry?
Routes of entry are:
- Nasal (most common)—droplet infection
- Oral
- Percutaneous
- Direct inoculation
- Transplacental.
* Pre-exam preparation for medicine, HN Sarker
What are the sites of primary tuberculosis?
The sites of primary tuberculosis are:
- Lungs
- Intestine
- Tonsil
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What are the common sites of pulmonary TB?
The sites of pulmonary TB are:
- Primary pulmonary TB
- Subpleural lesion.
- Postprimary TB
- Apical lesion.
* Pre-exam preparation for medicine, HN Sarker
What are the sites of extrapulmonary TB?
The sites of extrapulmonary TB are:
- Lymph node (20%–40%)—Cervical and supraclavicular are most common
- Serous membrane (like pleura 20%–25%, peritoneum)
- Meninges
- Intestine
- Genitourinary (5%–18%)
- Bones and joints
- Liver
- Adrenal gland.
* Pre-exam preparation for medicine, HN Sarker
What are the organs resistant to develop TB?
The organs are
- Cardiac muscle
- Skeletal muscle
- Thyroid gland
- Pancreas
* Pre-exam preparation for medicine, HN Sarker
What are the clinical features of pulmonary tuberculosis?
The clinical features of pulmonary tuberculosis are:
- Asymptomatic
- Symptomatic
- Respiratory symptoms
- Cough >3 weeks
- Sputum production
- Hemoptysis
- Chest pain
- Shortness of breath
- Localized wheez.
- General symptoms
- Fever (low grade with evening rise of temperature and relieved at late night by sweating)
- Weight loss
- Anorexia
- Signs
- No physical signs in most of the cases
- Signs of
- Fibrosis
- Collapse
- Pleural effusion
- Pneumothorax
- Cavitary lesion may be found.
- Respiratory symptoms
* Pre-exam preparation for medicine, HN Sarker
What are the clinical presentations of pulmonary TB?
- Chronic cough, often with haemoptysis
- Pyrexia of unknown origin
- Unresolved pneumonia
- Exudative pleural effusion
- Asymptomatic (diagnosis on chest X-ray)
- Weight loss, general debility
- Spontaneous pneumothorax
* Davidson’s Principles and Practice of Medicine, 22nd Edition Page: 691
The histological findings are:
- Caseating granuloma
- Epithelioid cell
- Multinucleated giant cell.
Figure: Tuberculous granuloma. Normal lung tissue is lost and replaced by a mass of fibrous tissue with granulomatous inflammation characterised by large numbers of macrophages and multinucleate giant cells (white arrow). The central area of this focus shows caseous degeneration (black arrow).
* Pre-exam preparation for medicine, HN Sarker; Figure: Davidson’s Principles and Practice of Medicine, 22nd Edition Page: 689
What are the radiological presentations/findings of pulmonary tuberculosis?
The radiological presentations are:
- Soft patchy opacities
- Consolidation
- Collapse
- Cavitation
- Fibrosis
- Miliary shadowing
- Pleural effusion/empyema.
* Pre-exam preparation for medicine, HN Sarker
What type of opacity is found in chest X-ray of a pulmonary TB patient?
Soft patchy opacities.
* Pre-exam preparation for medicine, HN Sarker
How will you investigate a case of sputum positive pulmonary TB during treatment?
After starting treatment with anti-TB drugs, sputum should be examined after 2, 3, and 5 months.
* Pre-exam preparation for medicine, HN Sarker
What are the aims of treatment of tuberculosis?
The aims are:
- To interrupt TB transmission by rendering patient noninfectious thus reducing mortality and morbidity.
- To prevent development of drug resistance.
* Pre-exam preparation for medicine, HN Sarker
What is the basis of combination therapy?
- To prevent the emergence of resistance, e.g. INH acts on rapidly growing bacteria, pyrazinamide enters into the caseous material, refampicin acts on dormant bacilli.
- To prevent resistance due to spontaneous mutation.
* Pre-exam preparation for medicine, HN Sarker
Why multidrug treatment is rational?
Multidrug treatment is rational due to:
- Better patient compliance
- Prevent drug resistance.
* Pre-exam preparation for medicine, HN Sarker
What are the advantages of fixed drug combinations (FDC)?
The advantages of FDC are:
- Prescription errorless likely to occur due to straight-forward dose recommendations and easier patient weight to dose adjustment.
- Small number of tablet to be ingested.
- Decreased drug resistance
* Pre-exam preparation for medicine, HN Sarker
Why long-term treatment is required?
Long-term treatment is required because:
- Mycobacterium tuberculosis multiplies slowly.
- Intensive phase rapidly reduces bacterial population.
- Continuation phase destroys the remaining bacteria.
* Pre-exam preparation for medicine, HN Sarker
What are the drugs used in TB?
- 1st line drugs
- INH
- Rifampicin
- Pyrazinamide
- Ethambutol
- Streptomycin
- Thiacetazone.
- 2nd line drugs
- Aminoglycosides : Kanamycin and amikacin
- Thionamides: Ethionamide
- Fluoroquinolone
- Cycloserine
- Para-aminosalicylic acid
- Clofazimine and rifabutin.
* Pre-exam preparation for medicine, HN Sarker
What is 6 months regimen?
Initial phase— 2 months.
Continuation phase—4 months.
* Pre-exam preparation for medicine, HN Sarker
Name a single side effect from each of the 1st line anti-TB drugs?
- INH—Peripheral neuropathy
- Rifampicin — Hepatitis
- Pyrazinamide—Hepatitis/ Hyperuricemia (gouty arthritis)
- Ethambutol—Optic neuritis
- Streptomycin—Ototoxicity (8th cranial nerve palsy)
- Thiacetazone—Steven-Johnson’s syndrome.
* Pre-exam preparation for medicine, HN Sarker
How can you assess response to anti-TB treatment?
Treatment response—
- By 2nd week—Sputum smear becomes negative
- After 4 weeks—Feeling well, weight gain, no fever, no cough and sputum
- By 2 months—80% culture negative
- By 3 months—100% culture negative
- Chest radiograph— Should have improved.
* Pre-exam preparation for medicine, HN Sarker
How can you assess response to anti-TB treatment?
Management of patient—
- Anti-TB drugs should be stopped.
- Liver function tests are done.
- Viral serology are done to exclude viral hepatitis.
- Supportive measures should be taken, e.g. nutrition.
- Wait till jaundice disappears and liver function returns to normal.
- After that anti-TB drugs will be reintroduced slowly.
* Pre-exam preparation for medicine, HN Sarker
