TB — Overview (incl. Who to Test)

PERSONS TO TEST FOR TUBERCULOSIS

1. Persons Likely to be Infected with Mtb

  • poor / homeless
  • lived in 3rd World
  • contact w/ Active TB case
  • incarcerated / institutionalized
  • Native American / Alaskan
  • Injection Drug Use

2.  Persons at High Risk of Active TB if Infected

  • HIV
  • Dialysis
  • Silicosis
  • Diabetes (slight ↑ risk)
  • Head & Neck Carcinoma
  • Lymphoma / Leukemia
  • Immunosuppressive Meds (organ transplant meds; prednisone >10-15 mg/d, for >3 weeks;  Tumor Necrosis Factor Inhibitors)
  • Malnutrition (& predisposing illnesses)
  • Tuberculin test converted neg to pos in last 2 yrs

PUBLIC HEALTH PARADIGM FOR “CLASSES” OF TB

TB-0  —  No Exposure
  • Don’t perform tuberculin testing
TB-1  —  Exposure
  • Case- contact.  Maybe got infected with Mtb
  • Perform tuberculin test to determine
  • Up to 10 weeks for Tuberculin Test to turn Positive
  • Temporary classification pending tuberculin testing results
TB-2  —  Latent TB Infection
  • Tuberculin test positive (PPD or IGRA)
  • Asymptomatic.  Not contagious.
  • 5%- 10% lifetime chance of developing active TB
  • Many patients candidates for INH Tx (to prevent reactivation)
TB-3  —  Active TB Disease
  • Main Sx:  Cough >3wks w/o improvement, no other Dx likely
    • Maybe fever, sweats, hemoptysis, weight loss (but usually not)
  • Suspect:  Abnl. CXR (cavities, apical infiltrates)
  • Sputum for AFB:  smear 50% sensitive, PCR 80%, Culture 98%
  • In other organs:  urine / CSF / tissue biopsy,  for AFB
  • Pathologic.  Needs Tx.  Contagious
  • Nat Hx: 50% die by 5 yrs, 30% cure on own, 20% remit & relapse
TB-4  —  Healed TB, inactive (“Old Scar”)
  • Asymptomatic pt. w/ abnormal CXR
  • Obtain 3 sputums, await final cultures on conventional media (60 days)
  • When cultures no growth at 60 days, repeat CXR
  • If no change in CXR (= “stability”), can Dx “Old Scar”
  • High risk of reactivation; needs INH Tx.  Not contagious.
TB-5  —  R/O Active TB; W/U pending [see TB-3 above]
  • If high clinical suspicion, start 4-drug Tx pending results
  • If low suspicion, await sputum results
  • Temporary classification pending results

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