Tuberculosis is a topic covered in the 5-Minute Emergency Consult.

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  • Tuberculosis (TB) is an infectious disease with protean manifestations, causing significant global morbidity and mortality.

  • Infectious droplet nuclei are inhaled through the respiratory tract.
  • Bacteria are dispersed through coughing, sneezing, speaking, singing.
  • Primary TB/latent TB infection (LTBI):
    • Initial infection occurs when organisms enter the alveoli, become engulfed by macrophages, and spread via regional lymph nodes to the bloodstream.
    • Patients are usually asymptomatic.
    • May be progressive/fatal in immunocompromised hosts.
    • Positive reaction to purified protein derivative (PPD) indicates past exposure or infection.
    • Negative PPD does not rule out active TB.
    • May progress to active TB (5–10%).
  • Reactivation TB:
    • LTBI becomes active TB.
    • Systemic (15%) and pulmonary (85%) symptoms.
  • TB affects about one-third of the world's population (90 million new cases in the past decade worldwide, with about 30 million deaths).
  • Centers for Disease Control and Prevention (CDC) statistics from 2011 show TB in US at an all-time low.
  • TB rates in US have continued to decline since 1993.
  • Increase in US foreign-born cases
  • Still an estimated 10–15 million people are infected in US alone.


  • Infection with Mycobacterium tuberculosis, a slow-growing, aerobic, acid-fast bacillus resulting in disease.
  • Humans are the only known reservoir.
  • Recent TB epidemics:
    • HIV-infected patients
    • Multidrug-resistant TB (MDR-TB)
    • Extensively drug-resistant TB (XDR-TB):
      • High mortality, few effective drugs

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