Practice Guidelines

Tuberculosis: Guidelines for Diagnosis from the ATS, IDSA, and CDC

 

Am Fam Physician. 2018 Jan 1;97(1):56-58.

Author disclosure: No relevant financial affiliations.

Key Points for Practice

• An IGRA is recommended over a TST in persons at least five years of age who are likely to have M. tuberculosis infection

• If pulmonary TB is suspected, an AFB smear can be performed; three specimens are typically tested.

• If extrapulmonary TB is suspected, specimens should be collected from those sites for mycobacterial culture.

From the AFP Editors

Persons with Mycobacterium tuberculosis infection may have no clinical evidence of disease and present asymptomatically, known as latent tuberculosis infection (LTBI) or symptomatically, known as tuberculosis (TB). TB, which is a chief cause of infection-related morbidity and mortality, can be difficult to diagnose. For this reason, the American Thoracic Society (ATS), Infectious Diseases Society of America (IDSA), and Centers for Disease Control and Prevention (CDC) have provided guidance on diagnosing TB in children and adults.

Recommendations

LTBI TESTING

LTBI testing recommendations are outlined in Table 1. It should be noted that although interferon-gamma release assays (IGRAs) and tuberculin skin tests (TSTs) can identify M. tuberculosis infection, they cannot differentiate between TB and LTBI; therefore, active TB needs to be excluded via presence or absence of symptoms or signs on radiography before initiating LTBI treatment.

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TABLE 1.

Summary of Recommendations for LTBI Testing

Group*Testing strategyConsiderations

Likely to be infected

Adults

Prevalence of bacillus Calmette-Guérin vaccination

High risk of progression (TST ≥ 5 mM)

Acceptable: IGRA or TST

Expertise of staff or laboratory

Consider dual testing, in which a positive result from either would be considered positive†

Test availability

Children ≤ 5 years

Patient and staff perceptions

Preferred: TST

Programmatic concerns

Acceptable: IGRA or TST

Consider dual testing, in which a positive result from either would be considered positive†

Likely to be infected

Preferred: IGRA where available

Low to intermediate risk of progression (TST ≥ 10 mM)

Acceptable: IGRA or TST

Unlikely to be infected (TST > 15 mM)

Testing for LTBI is not recommended

If necessary:

Preferred: IGRA where available

Acceptable: IGRA or TST

For serial testing

Acceptable: IGRA or TST

Consider repeat or dual testing, in which a negative result from either would be considered negative‡


IGRA = interferon-gamma release assay; LTBI = latent tuberculosis infection; TST = tuberculin skin test.

*—These groups are determined on the risk for infection with tuberculosis and risk of progression and benefit of therapy.

†—Performing a second diagnostic test when the initial test is negative is a strategy to increase sensitivity. This may reduce specificity, but the panel decided that this is an acceptable trade-off in situations in which the consequences of missing LTBI (i.e., not treating persons who may benefit from therapy) exceed the consequences of inappropriate therapy (i.e., hepatotoxicity).

‡—Performing a confirmatory test following an initial positive result is based on the evidence that false-positive results are common among persons who are unlikely to be infected with Mycobacterium tuberculosis and the committee's presumption that performing a second test in those patients whose initial test result was positive will help identify initial false-positive results.

Adapted with permission from Lewinsohn DM, Leonard MK, LoBue PA, et al. Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention clinical practice guidelines: diagnosis of tuberculosis in adults and children. Clin Infect Dis. 2017;64(2):114.

TABLE 1.

Summary of Recommendations for LTBI Testing

Group*Testing strategyConsiderations

Likely to be infected

Adults

Prevalence of bacillus Calmette-Guérin vaccination

High risk of progression (TST ≥ 5 mM)

Acceptable: IGRA or TST

Expertise of staff or laboratory

Consider dual testing, in which a positive result from either would be considered positive†

Test availability

Children ≤ 5 years

Patient and staff perceptions

Preferred: TST

Programmatic concerns

Acceptable: IGRA or TST

Consider dual testing, in which a positive result from either would be considered positive†

Likely to be infected

Preferred: IGRA where available

Low to intermediate risk of progression (TST ≥ 10 mM)

Acceptable: IGRA or TST

Unlikely to be infected (TST > 15 mM)

Testing for LTBI is not recommended

If necessary:

Preferred: IGRA where available

Acceptable: IGRA or TST

For serial testing

Acceptable: IGRA or TST

Consider repeat or dual testing, in which a negative result from either would be considered negative‡


IGRA = interferon-gamma release assay; LTBI = latent tuberculosis infection; TST = tuberculin skin test.

*—These groups are determined on the risk for infection with tuberculosis and risk of progression and benefit of therapy.

†—Performing a second diagnostic test when the initial

Author disclosure: No relevant financial affiliations.

Coverage of guidelines from other organizations does not imply endorsement by AFP or the AAFP.

This series is coordinated by Sumi Sexton, MD, Associate Deputy Editor.

A collection of Practice Guidelines published in AFP is available at http://www.aafp.org/afp/practguide.

 

 

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