Tuberculosis, Pulmonary

• • Gram-positive rods, often dormant but remain alive for the life of the host

  • Initial infection affects midzone of lungs, causing caseation in a few weeks

  • Regional hilar lymph nodes become enlarged; most cases arrest at this stage

  • If progresses, giant cells produce a typical tubercle

  • Latent disease occurs when dormant tubercles reactivate in elderly or immunocompromised patients

  • Apical segments of upper lobes most often affected in latent disease

  • Extrapulmonary disease may involve pericardium, bones, joints, urinary tract, meninges, lymph nodes, pleural space

Epidemiology

• • Had markedly declined from 1953 until 1984 due to anti-TB drugs

  • Since 1984, has increased due to emergence of HIV

  • 25,000 new cases annually

  • < 20% of population in the United States is tuberculin-positive

  • 95% of cases are due to infection with Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium avium-intracellulare

Symptoms and Signs

• • Minimal symptoms in many

  • Fever, cough

  • Anorexia, weight loss

  • Night sweats, excessive perspiration

  • Chest pain

  • Lethargy, fatigue

  • Dyspnea

  • Erythema nodosum seen in active disease

Laboratory Findings

• • Purified protein derivative (PPD): False-negative due to improper testing, anergy

  • Anergy due to disseminated disease, sarcoidosis, lymphomas, immunosuppressive drugs (used in HIV, transplant patients)

  • Sputum culture for mycobacterium

Imaging Findings

• • Chest film

  • -Involvement of apical and posterior upper lobes (85%)

    -10% of cases affect superior lower lobes and seen most often in women, blacks and diabetics

    -Variations: Cavitation, acute TB pneumonia, miliary TB, bronchiectasis, tuberculoma

Rule Out

• • Bronchogenic carcinoma

  • Fungal infections, such as histoplasmosis

• • PPD

  • Sputum culture

  • Gastric aspirate, tracheal washing culture

  • Pleural fluid culture; pleural and lung biopsies may be needed for diagnosis

• • Multidrug regimens including isoniazid, rifampin, pyrazinamide, and ethambutol

Surgery

• • Role of surgery diminished dramatically by effective medications

Indications

• • Failure of medical therapy

  • Performance of diagnostic procedures

  • Destroyed lung, cavitary lesions

  • Postoperative complications

  • Persistent bronchopleural fistula

  • Intractable hemorrhage

Medications

• • Isoniazid

  • Streptomycin

  • Ethambutol

  • Rifampin

Complications

• • TB empyema: Treated by pulmonary decortication, or drainage if associated with pyogenic infection or bronchopleural fistula

Prognosis

• • Mortality 10% with medical treatment

  • Perioperative mortality: 1-10%

  • Relapse rate is 4%

References