Updated: 1/31/2021

Pulmonary Tuberculosis and PPD

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Snapshot
  • A 37-year-old man presents to his primary care physician with subjective fever, malaise, and cough. He reports a few episodes of night sweats and has noted an unintentional 15-pound loss over the course of 2 months. Yesterday, he noted bloody sputum. He recently immigrated from Central Africa and currently lives with many family members in a small apartment. Chest radiograph demonstrates a cavitary lesion in the right upper lobe of the lung.
Introduction
  • Definition
    • infection of the respiratory system caused by Mycobacterium tuberculosis
  • Epidemiology
    • risk factors
      • close contact with someone with tuberculosis (Tb)
        • e.g., prisons and homeless shelters
      • immigrating from highly endemic regions such as
        • Bangladesh
        • Cambodia
        • Central African Republic
      • working in hospitals and nursing homes
      • immunosuppression (e.g., HIV, diabetes, and on immunosuppressive medications)
      • substance use disorder 
        • most important for diffuse reticulonodular pattern
  • Etiology
    • Mycobacterium tuberculosis
  • Transmission
    • inhaling airborne particles (droplet nuclei)
    • suspected patients should be placed on respiratory isolation precautions during workup 
  • Pathophysiology
    • droplet nuclei produced by coughing gets inhaled → recruits macrophages when in the alveoli dissemination of macrophage infected cells into deeper tissues and caseating granuloma formation
  • Extrapulmonary Tb
    • meningitis
    • Pott disease (vertebral infection) 
    • miliary Tb
    • pericarditis
    • adrenal gland infection
    • genitourinary Tb
Presentation
  • Symptoms
    • cough (productive or nonproductive)
    • hemoptysis
    • night sweats
    • fever
    • loss of appetite
  • Physical exam
    • weight loss
    • although physical exam is not helpful in diagnosing Tb, it is important to assess for extrapulmonary involvement
      • e.g., hepatosplenomegaly, lymphadenopathy, scrotal, and pelvic tenderness
Imaging
  • Chest radiography
    • findings
      • non-specific findings (e.g., patchy or lobar consolidation or non-detectable lesions)
      • cavitary lesions
      • miliary nodules
      • hilar adenopathy
      • pleural effusion
Studies
  • Sputum specimen
    • acid-fast bacilli
    • culture
    • nucleic acid amplification tests
  • Blood
    • interferon-gamma release assay
  • Tuberculin skin test 
    • results in a delayed immune response with the administration of purified protein derivatives (PPD) from Mycoplasma tuberculosis
      • measured in 48-72 hours
    • findings
      • ≥ 5 mm
        • considered a positive test in patients with
          • HIV
          • recent Tb exposure
          • chest radiographic findings consisted of healed Tb infection
          • organ transplantation or on immunosuppressants
      • ≥ 10 mm
        • considered a positive test in patients with
          • injection drug users
          • chronic diabetes
          • chronic renal failure
          • employees in high-risk settings (e.g., physicians, nurses, or prison workers)
          • recent immigrant from endemic country
      • ≥ 15 mm
        • considered a positive test in patients with no known risk factors
Treatment
  • Medical
    • rifampin, isoniazid, pyrazinamide, and ethambutol (RIPE) therapy
      • indication
        • treatment of choice for the 2-month initial phase
          • 4-month continuation phase is with rifampin and isoniazid
      • side effects
        • isoniazid should be given with vitamin B6 (pyridoxine) to prevent peripheral neuropathy
          • B6 deficiency can cause refractory seizures
            • treat with pyridoxine 
        • rifampin, isoniazid, and pyrazinamide can cause liver toxicity
        • ethambutol results in optic neuropathy
    • isoniazid
      • indication
        • for Tb prophylaxis
Complications
  • Tuberculoma
  • Aspergilloma
  • Acute respiratory failure


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Questions (9)
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(M2.ID.16.4686) A 21-year-old U.S. born first year medical student with no prior hospital or healthcare work presents to the physician for a routine physical exam. The patient is HIV negative, denies drug use, and denies sick contacts. The physician places a purified protein tuberculin test in the patient's right forearm intradermally. What is the proper time to read the test and induration diameter that would indicate a positive test result?

QID: 107421
1

24 hours and 18mm diameter

0%

(0/8)

2

36 hours and 7mm diameter

12%

(1/8)

3

48 hours and 11mm diameter

38%

(3/8)

4

72 hours and 16mm diameter

38%

(3/8)

5

96 hours and 14mm diameter

0%

(0/8)

M 6 E

Select Answer to see Preferred Response

(M3.ID.15.19) A 33-year-old nurse who was born in the United States and has lived in the US all her life is referred to an infectious disease specialist after she exhibited a PPD skin test with 17 mm of induration. She denies any cough, shortness of breath, hemoptysis, weight loss, fatigue, fevers, or night sweats over the last several months. However, she works in the federal penitentiary system and has also provided aid on foreign medical mission trips to Haiti in the past few years. Her temperature is 97.0°F (36.1°C), blood pressure is 120/81 mmHg, pulse is 82/min, respirations are 15/min, and oxygen saturation is 98% on room air. An initial chest radiograph is unremarkable. Which of the following is the most appropriate management of this patient?

QID: 102773
1

Rifampin only

47%

(7/15)

2

No management indicated

33%

(5/15)

3

Quantiferon gold

7%

(1/15)

4

Repeat PPD in 1 week

7%

(1/15)

5

Rifampin, isoniazid, pyrazinamide, and ethambutol

0%

(0/15)

M 11 E

Select Answer to see Preferred Response

(M2.ID.15.8) A 29-year-old man who recently returned from 4 years of missionary work in India presents to your primary care office complaining of numbness and tingling in his toes bilaterally for the last several weeks. The patient states that his past medical history is significant only for a "lung infection," which was treated with antibiotics. He has brought with him copies of his medical records from India, which include a copy of a chest radiograph (Figure A). Which of the following dietary supplements could have prevented this adverse effect?

QID: 104893
FIGURES:
1

Vitamin A

0%

(0/17)

2

Vitamin B6

76%

(13/17)

3

Vitamin B12

18%

(3/17)

4

Vitamin C

0%

(0/17)

5

Vitamin E

0%

(0/17)

M 5 E

Select Answer to see Preferred Response

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