Latent tuberculosis infection

From IDWiki

Latent tuberculosis infection (LTBI)

Definition

  • Prior exposure to TB
  • Goal is to identify those who are at increased risk of developing active TB and would benefit from treatment

Investigations

  • Tuberculin skin test (TBST)
    • Sens 90%, Spec >95
  • Interferon-gamma release assay (IGRA)
    • Sn 95%, Sp >95%
    • Preferred for those who have received BCG after infancy

Positive TBST

  1. Is it truly positive?
    • Consider IGRA
    • BCG vaccine can be considered a cause of false positive when
      • vaccine given after 12 months of age, and
      • patient has no risk factors, and
      • either Canadian-born non-Aboriginal, or not from endemic country
  2. Rule out active TB
    • signs/symptoms
    • CXR or CT chest
    • Sputum x3 if coughing or cavitary lesions
  3. Evaluate risk of reactivation treatment
    • INH 300 daily x9 mo with pyridoxine
    • baseline liver enzymes and vision testing

Reading

Tools

References

  1. ^  Canadian Tuberculosis Standards. 7th edition. ed. Template:ISBN. OCLC 978699031.
  2. ^  Dick Menzies, Menonli Adjobimey, Rovina Ruslami, Anete Trajman, Oumou Sow, Heejin Kim, Joseph Obeng Baah, Guy B. Marks, Richard Long, Vernon Hoeppner, Kevin Elwood, Hamdan Al-Jahdali, Martin Gninafon, Lika Apriani, Raspati C. Koesoemadinata, Afranio Kritski, Valeria Rolla, Boubacar Bah, Alioune Camara, Isaac Boakye, Victoria J. Cook, Hazel Goldberg, Chantal Valiquette, Karen Hornby, Marie-Josée Dion, Pei-Zhi Li, Philip C. Hill, Kevin Schwartzman, Andrea Benedetti. Four Months of Rifampin or Nine Months of Isoniazid for Latent Tuberculosis in Adults. New England Journal of Medicine. 2018;379(5):440-453. doi:10.1056/nejmoa1714283.