TB

Question 1

What type of organisms are tuberculosis bacteria?

Answer 1

Obligate aerobes

They grow most successfully in tissues with high oxygen content, such as the lungs.

Question 2

Describe the physical characteristics of Mycobacterium tuberculosis.

Answer 2

Nonmotile, nonsporeforming, pleomorphic rods ranging from 1 to 10 μm in length and 0.2 to 0.6 μm in width.

Question 3

What is the role of mycolic acids in Mycobacterium tuberculosis?

Answer 3

They are the most distinctive lipids in the complex cell wall structure.

Question 4

What staining property do Mycobacterium tuberculosis exhibit?

Answer 4

They are ‘acid-fast’ due to their lipid-rich cell wall.

Question 5

Which staining techniques can demonstrate the acid-fast property of Mycobacterium tuberculosis?

Answer 5

Basic fuchsin stain techniques, such as Ziehl–Neelsen and Kinyoun methods, or the fluorochrome method using auramine and rhodamine stains.

Question 6

What occurs in the first stage of tuberculosis exposure?

Answer 6

An individual has been in close proximity to a person with contagious TB disease.

Question 7

What characterizes the second stage of tuberculosis infection?

Answer 7

An individual has inhaled the causative organism.

Question 8

What are the symptoms of TB disease?

Answer 8

Symptoms, signs, or radiographic manifestations.

Question 9

How is tuberculosis primarily transmitted?

Answer 9

Inhalation of mucous droplets that become airborne.

Question 10

What is a hallmark of childhood pulmonary TB?

Answer 10

Isolated lymphadenopathy with enlargement of regional hilar, mediastinal, or subcarinal lymph nodes on chest X-ray.

Question 11

What is the risk of developing TB disease in children under 2 years of age?

Answer 11

25%–30% risk of progressing from infection to disease; higher for children under 1 year (40%–50%).

Question 12

What is the primary (Ghon) focus in tuberculosis?

Answer 12

A localized pneumonic parenchymal inflammatory process induced by tubercle bacilli reaching a terminal airway.

Question 13

What is the incubation period for tuberculosis?

Answer 13

3–8 weeks.

Question 14

What is a common complication of untreated primary complex TB?

Answer 14

Calcification of the lung parenchyma and/or regional lymph nodes.

Question 15

What is the most common manifestation of TB disease?

Answer 15

Intrathoracic TB.

Question 16

What are the symptoms of progressive primary infection in symptomatic children?

Answer 16

• Weight loss
• Fatigue
• Fever
• Chronic cough.

Question 17

What can occur when the area of caseation discharges into a bronchus?

Answer 17

Primary cavity leading to possible endobronchial spread.

Question 18

What is the prognosis for children with progressive primary disease when treated appropriately?

Answer 18

Excellent.

Question 19

What can cause bronchial obstruction in tuberculosis?

Answer 19

Enlarged infected lymph nodes causing nodal compression, inflammatory edema, polyps, or caseous material.

Question 20

What is the most frequently affected lobe in bronchial disease due to TB?

Answer 20

Right upper lobe.

Question 21

What are the symptoms of pleural TB?

Answer 21

• Acute chest pain
• High fever
• Dry cough.

Question 22

What are the three clinical forms of extrapulmonary dissemination in TB?

Answer 22

• Occult
• Protracted hematogenous TB
• Miliary TB.

Question 23

What is the most common form of extrathoracic disease in children?

Answer 23

TB of the superficial lymph nodes (scrofula).

Question 24

What diagnostic imaging is hallmark for pediatric TB?

Answer 24

Intrathoracic lymphadenopathy.

Question 25

What is the role of the tuberculin skin test (TST)?

Answer 25

Indicates TB infection, with induration reaching maximal size at 48–72 hours.

Question 26

What is the cutoff for a positive TST in HIV-infected individuals?

Answer 26

5 mm.

Question 27

What do interferon-gamma release assays (IGRAs) identify?

Answer 27

Genes in the M. tuberculosis genome.

Question 28

What is the procedure for obtaining a gastric aspirate for TB diagnosis?

Answer 28

50 mL of early-morning gastric contents after fasting for at least 8–10 hours.

Question 29

What is the purpose of interferon-gamma release assays (IGRAs)?

Answer 29

Identification of genes in the M. tuberculosis genome ## Footnote IGRAs cannot differentiate between TB infection and TB disease.

Question 30

What is the procedure for obtaining a gastric aspirate?

Answer 30

50 mL of early-morning gastric contents after fasting for at least 8–10 hours ## Footnote Usually entails hospitalization but can be performed at home or clinic by a nurse.

Question 31

What is the yield of M. tuberculosis recovery from gastric aspirates in children with radiographic evidence?

Answer 31

Roughly 40% ## Footnote This is based on studies involving children.

Question 32

What is the significance of sputum induction in diagnosing TB?

Answer 32

Requires treatment with inhaled beta agonist followed by hypertonic saline ## Footnote Increases yield when adequate specimens and multiple specimens are obtained.

Question 33

What tests can help clinicians considering a diagnosis of TB disease?

Answer 33

Either IGRA or TST ## Footnote Positive results increase the likelihood of M. tuberculosis causing symptoms.

Question 34

What is the easiest and least expensive diagnostic procedure for TB?

Answer 34

Acid-fast staining and microscopic examination ## Footnote Positive results occur in < 10% of children with pulmonary TB.

Question 35

What is considered the gold standard for diagnosing childhood TB?

Answer 35

Triad of an abnormal CXR, a positive TST or IGRA result, and history of contact with an infectious TB case ## Footnote This triad is critical for diagnosis.

Question 36

What does the Xpert methodology detect?

Answer 36

Presence of M. tuberculosis DNA and mutations in the rpoB gene ## Footnote This method is user-friendly and has a processing time of 2 hours.

Question 37

What is the recommended treatment for children < 5 y/o with known exposure to TB?

Answer 37

Initial test of infection performed at the time of presentation ## Footnote If negative, treatment with INH is advised.

Question 38

What is Isoniazid Preventative Therapy (IPT)?

Answer 38

Daily INH for 6 months in HIV-uninfected children under 5 with contagious TB contact ## Footnote Given if they lack signs or symptoms of TB disease.

Question 39

What are the criteria for asymptomatic TB infection in children?

Answer 39

Reactive TST or IGRA, normal chest radiograph, no clinical evidence of TB disease ## Footnote Indicates presumed infection with small numbers of viable tubercle bacilli.

Question 40

What is the recommended treatment duration for TB infection in children?

Answer 40

9 months of INH ## Footnote Administered either daily or twice weekly.

Question 41

When is Rifampicin used in TB treatment?

Answer 41

When INH is not tolerated or if exposed to INH-resistant, RIF-susceptible isolate ## Footnote Administered in a daily 4-month-long course.

Question 42

What are common adverse effects of both INH and RIF?

Answer 42

Elevated transaminases, abdominal pain, vomiting ## Footnote Rarely cause overt hepatitis.

Question 43

What is the initial treatment regimen for pulmonary tuberculosis?

Answer 43

4-drug regimen recommended ## Footnote Involves INH, RIF, pyrazinamide, and ethambutol.

Question 44

What is the treatment approach for drug-resistant tuberculosis?

Answer 44

Requires 4 to 5 drugs to which the strain is susceptible ## Footnote At least 2 of these should be bactericidal.

Question 45

What is the recommended treatment duration for MDR-TB in children?

Answer 45

Traditionally treated for 18–24 months ## Footnote 18-month regimen for widespread disease or cavitary lung lesions.

Question 46

What adjunctive therapy is recommended for children treated with INH?

Answer 46

Pyridoxine (25–50 mg/day) ## Footnote Recommended for those with nutritional deficiencies or symptomatic HIV.

Question 47

What are the major goals of follow-up during antituberculosis therapy?

Answer 47

Promoting adherence, monitoring toxicity, assessing clinical response ## Footnote Patients should be evaluated monthly.

Question 48

What is the effect of BCG vaccination in children?

Answer 48

Decreases the risk for developing severe forms of TB disease ## Footnote Particularly effective in very young children.

Question 49

What is the risk of BCG vaccination in HIV-infected infants?

Answer 49

Significant risk of developing disseminated BCG disease ## Footnote Associated with a case fatality rate >75%.