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


Definition and Classification
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:

  1. Pulmonary tuberculosis
    • Primary
    • Postprimary
      • Reactivation
      • Reinfection
  2. Extrapulmonary tuberculosis
    • Outside the lung parenchyma (according to USA)
    • Outside the lung and pleura (according to UK).

According to bacteriological specimen

  1. Smear positive
    • 2 sputum positive for AFB
    • 1 sputum positive with chest X-ray abnormality
    • 1 sputum positive with one culture positive.
  2. 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

  1. Category 1
  2. 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
Epidemiology
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
Etiology and Pathophysiology
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.
* Pre-exam preparation for medicine, HN Sarker
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
* Pre-exam preparation for medicine, HN Sarker
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
Clinical Manifestations
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.
* 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
Examination
Investigations

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
Diagnosis
Treatment
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?
  1. 1st line drugs
    • INH
    • Rifampicin
    • Pyrazinamide
    • Ethambutol
    • Streptomycin
    • Thiacetazone.
  2. 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
Complications
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
Notes
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