• U.S.: 10–15 million infected (15× ↑ risk if foreign-born or minority); worldwide: ~2 billion
  • Multidrug-resistant (MDR) TB: resistant to INH & rifampin. Can occur as 1° infxn.
  • Extensively drug-resistant (XDR) TB resistant to INH, RIF, FQ, and injectables
  • Risk factors (NEJM 2011;364:1441)
    • Acquisition: immigrant from high-prevalence area, homeless, IVDU or medically underserved, resident or worker in jail or long-term facility, healthcare worker, close contact to Pt w/ active TB
    • Reactivation: risk is 5% in first 2 yr, 5–10% over lifetime, but higher if HIV ⊕, immunosupp. incl. derweight, smoker, IVDU, alcohol