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Treatment of Latent Tuberculosis Infection (LTBI)

General information

Managing Patients with Positive Tuberculin Skin Tests (TSTs) or Interferon Gamma Release Assays (IGRAs)

A chest x-ray must always be obtained when there is a positive TST or IGRA to rule out active disease.

If the chest x-ray is not suggestive of active TB, the patient is a candidate for latent TB treatment (this was previously called “prophylaxis”.)

There are four regimens that can be used to treat LTBI.

Drugs Duration Interval Minimum doses
* must use directly observed therapy
Isoniazid 9 months Daily 270
Twice weekly* 76
Isoniazid 6 months Daily 180
Twice weekly* 52
Isoniazid and Rifapentine 3 months Once weekly* 12
Rifampin 4 months Daily 120

San Mateo County follows treatment recommendations set forth by the California Tuberculosis Controller’s Association (CTCA) adapted from the Centers for Disease Control (CDC), At the present time, the CTCA LTBI guidelines (2006) are under revision.  Until such time at the guidelines are updated, the county recommends following the 2010 LTBI guidelines set forth by the CDC.

For contacts to a case of drug resistant tuberculosis, specific treatment recommendations may be made by San Mateo County’s TB program, depending on the susceptibility of the organism to which the contact was exposed.

Remember, we are available for consultation!