Tuberculin Reaction Size and Treatment of Latent Mycobacterium Tuberculosis Infection
| Risk Group | Tuberculin Reaction Size, mm |
|---|---|
| HIV-infected persons | ≥5 |
| Recent contacts of a patient with TB | ≥5a |
| Organ transplant recipients | ≥5 |
| Persons with fibrotic lesions consistent with old TB on chest radiography | ≥5 |
| Persons who are immunosuppressed, e.g., due to the use of glucocorticoids or tumor necrosis factor α inhibitors | ≥5 |
| Persons with high-risk medical conditionsb | ≥5 |
| Recent immigrants (≤5 years) from high-prevalence countries | ≥10 |
| Injection drug users | ≥10 |
| Mycobacteriology laboratory personnel; residents and employees of high-risk congregate settingsc | ≥10 |
| Children <5 years of age; children and adolescents exposed to adults in high-risk categories | ≥10 |
| Low-risk personsd | ≥15 |
aTuberculin-negative contacts, especially children, should receive prophylaxis for 2-3 months after contact ends and should then undergo repeat TST. Those whose results remain negative should discontinue prophylaxis. HIV-infected contacts should receive a full course of treatment regardless of TST results.
bThese conditions include silicosis and end-stage renal disease managed by hemodialysis
cThese settings include correctional facilities, nursing homes, homeless shelters, and hospitals and other health care facilities.
dExcept for employment purposes where longitudinal TST screening is anticipated, TST is not indicated for these low-risk persons. A decision to treat should be based on individual risk/benefit considerations.
Source: Adapted from Centers for Disease Control and Prevention: TB elimination—treatment options for latent tuberculosis infection (2011). Available at http://www.cdc.gov/tb/publications/factsheets/testing/skintestresults.pdf.