TB practice questions

Tuberculosis Overview, Pathophysiology & Etiology

• Tuberculosis (TB) is a chronic infectious disease.
• Recurrence is possible.
• Caused by Mycobacterium tuberculosis, a slender, rod-shaped bacterium (bacilli).
• Its waxy outer capsule resists destruction.
• Slow-growing, taking 2-12 weeks to trigger an immune response.
• Acid-fast bacilli (AFB) are a key characteristic.
• Primary infection site is the lungs, but it can spread to other organs.
• TB is a reportable disease and a public health concern.

Epidemiology of Active Tuberculosis Cases in Ohio (2019)

• Active TB cases in Ohio during 2019 were not very common overall.
• Lake County had zero cases.
• Cuyahoga County had 25 cases, up from the previous year.
• Summit County had 8 cases, down from the previous year.
• Ashtabula County had zero cases, the same as the previous year.
• In Ohio, 2018 had 178 cases, 2019 had 150 cases, a decrease of 28.
• Foreign-born individuals in Ohio had a high rate of TB (103 cases, 68.7%).

Pathophysiology & Etiology

• Inhalation of Mycobacterium tuberculosis bacilli into the lungs, specifically alveoli or respiratory bronchioles, initiates an inflammatory response.
• Phagocytic cells (neutrophils & macrophages) ingest and isolate the bacteria, preventing spread.
• A granulomatous lesion called a tubercle forms.
• A cellular immune response develops, which can be elicited with a TB skin test (2-12 weeks).

Pathophysiology & Etiology: Latent vs. Active TB

• Dormant (Latent) TB: An adequate immune response forms scar tissue around the tubercle, encapsulating the bacteria. Bacteria are inactive but not dead.
• Active TB: Inadequate immune response. The tubercle ruptures, releasing bacteria, leading to infectiousness and severe lung tissue damage (erosion/cavitation).

Classifications of TB

• Active TB: Infectious, clinical symptoms.
• Dormant (Latent) TB: Non-infectious, no clinical symptoms.
• Reactivation TB: Latent TB becomes active due to weakened immune systems (age, HIV/AIDS, immunosuppressive drugs, etc.).

Risk Factors for TB

• Immigrants/Foreign-born individuals in the US.
• Individuals with HIV/AIDS or altered immune function.
• Homelessness, shelters, prisons, and detention facilities.
• Overcrowded institutions, and poor living conditions.

Clinical Manifestations of TB

• Asymptomatic in early stages.
• Fever (typically low-grade).
• Night sweats.
• Dry cough, progressing to hemoptysis (blood-tinged sputum).
• Weight loss.
• Fatigue.
• Cough, pleuritic chest pain.
• Dyspnea (shortness of breath).

Prevention and Diagnostic Tests

• PPD/TST (Mantoux Test): Intradermal skin test, read 48-72 hours post-injection. >15mm induration is positive in all people. Redness alone is NOT indicative of a positive test.
• Sputum smear: Detects presence of AFB bacteria (rapid indicator); 3 specimens, 8-24 hours apart.
• Sputum culture: Confirmatory diagnosis (time-consuming).
• Chest X-ray: Look for dense lesions (apical, upper lobes), cavity formation.
• Interferon-gamma release assays (IGRA): Blood test to detect immune response to TB.
• Nucleic Acid Amplification (NAA): Rapidly identifies microorganisms; detects M. tuberculosis in hours.
• Special procedures (endotracheal suctioning, bronchoscopy, or gastric lavage): Occasionally required for obtaining specimen.
• Positive TB test does not equal active disease. Sputum & chest x-rays are routine.

Collaboration: Diagnostic Tests

• Chest X-rays show dense lesions (apical, upper lobe), including cavity formation.
• Interferon-gamma release assays (IGRA) quantify immune response; useful for those who received the BCG vaccine.
• Nucleic Acid Amplification (NAA) methods quickly identify the microorganisms.
• TB culture remains the gold standard.

Collaboration: Prevention & Precautions

• Provide patient and family education about TB transmission, prevention and precautions.
• TB transmission reduced by direct sunlight/ultraviolet light.
• Protect healthcare workers and others through standard and airborne precautions, including N95 masks, proper room placement and isolation technique.

Collaboration: Pharmacologic Therapy

• Antibiotics are used for preventing and treating TB infection.
• Goals: making the disease noncommunicable, reducing symptoms, and achieving the cure in the shortest time possible.
• First-line drugs (Active TB): isoniazid, rifampin, ethambutol, pyrazinamide, rifabutin, and rifapentine.
• Active TB: Medications for 2 months and then, add-on for 4-6 or 9 months, depending on factors like HIV, Directly Observed Therapy (DOT).
• Latent TB: Isoniazid for 6-9 months, rifampin for 4 months as needed.
• Monitoring/Surveillance for manifestations.

Collaboration: TB No Longer Considered Infectious When

• Clinical improvement is demonstrated.
• On medications for at least 2 weeks.
• Three consecutive negative AFB smears.

Common TB Nursing Diagnoses

• Ineffective breathing pattern
• Ineffective airway clearance
• Activity intolerance/fatigue
• Imbalanced nutrition
• Ineffective health maintenance/noncompliance