Approach to excluding tuberculosis (TB) disease in nonpregnant adults prior to treatment for TB infection (latent TB)^*

AFB: acid-fast bacilli; CXR: chest radiograph; IGRA: interferon-gamma release assay; PA: posteroanterior; TB: tuberculosis; TST: tuberculin skin test.

* TB infection (previously termed latent TB infection) may be established in the setting of epidemiologic risk factors, positive IGRA or TST, no symptoms, and normal CXR. TB disease (previously termed active TB) may be present in the setting of epidemiologic risk factors, positive IGRA or TST, abnormal CXR, and positive sputum (AFB smear or mycobacterial culture). Refer to UpToDate text for further discussion of TB terminology.

¶ Patients at increased risk for developing TB disease include: 1) individuals at increased risk of recent infection (eg, close contacts of persons with untreated TB disease; selected healthcare workers who may have occupational TB exposure), 2) individuals at high risk of reactivation if infected (eg, immunocompromised individuals), 3) individuals at moderate or slightly increased risk of reactiviation who reside in an area where TB is prevalent. Refer to UpToDate text for further discussion.

Δ Either IGRA or TST may be used; IGRA is preferable if available, particularly for patients who are unlikely to return to have the TST read and for patients with a history of Bacille Calmette-Guérin (BCG) vaccination administered after 12 months of age. Refer to the UpToDate topic on approach to diagnosis (screening) for tuberculosis infection (latent tuberculosis) in adults for discussion of test result interpretation.

◊ The presence of clinical symptoms is neither sensitive nor specific for TB disease.

§ A chest radiograph is considered abnormal if it demonstrates parenchymal abnormalities (particularly opacification of the upper lobe or superior segment of the lower lobe), pleural effusion, and/or hilar adenopathy. Isolated findings of granuloma/scarring do not warrant workup for TB disease.

¥ Positive acid-fast smear may reflect nontuberculous mycobacteria (colonization or disease). In settings with low incidence of TB (such as in the United States, where nontuberculous mycobacteria are more common than TB), culture results are needed to distinguish between nontuberculous mycobacteria and TB.

‡ For patients with abnormal chest radiograph but absence of parenchymal disease who have negative sputum culture, further diagnostic evaluation (such as bronchoscopy or tissue biopsy) may be warranted.

† Refer to separate UpToDate content for discussion of approach to treatment of TB infection.