What is the primary prophylaxis against latent Mycobacterium tuberculosis infection (LTBI) in patients with HIV infection?

Updated: Mar 09, 2021
  • Author: Justin R Hofmann, MD; Chief Editor: John Bartlett, MD  more...
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Tuberculosis (TB) is both the leading cause of death from infectious disease globally and the leading cause of morbidity and mortality among people living with HIV. [1]  Screening for TB in the HIV-infected population has been suboptimal, with only 47% to 65% of patients completing screening. The most common predisposition for TB is birth or residence outside of the United States. [1]  All persons with HIV should be tested for LTBI regardless of their epidemiologic risk for TB exposure (AII recommendation). [1]  All newly-diagnosed patients with HIV infection should be screened with a tuberculin skin test (TST) or interferon-gamma release assay (IGRA), and re-screened once the CD4 count rises to 200 if initially less. [1, 34]

Treatment for LTBI is indicated for all patients with a history of a positive TST result of 5 mm or greater or an IGRA who have not previously received therapy (AI recommendation). Patients with HIV who are close contacts of a person with infectious TB yet show no signs themselves of active TB, should be administered LTBI treatment regardless of screening results (AII recommendation). [1]  This appears particularly critical for HIV-seropositive children not on ART, as a Cochrane review of a South African study has shown a 69% reduction in the risk for active TB and a 54% reduction in death. [34]  An Ethiopian study showed improved outcomes in adults on combined ART and LTBI therapy. [35]

Active TB should be excluded by lack of symptoms and negative chest radiograph before prophylactic regimens are started. Active TB may be more likely in a patient with previous active TB (treated or untreated) than in a patient without a history of TB.

Isoniazid monotherapy for 9 months remains the preferred therapy, with proven efficacy, tolerability, and infrequent severe toxicity as a monotherapy (AI recommendation). [1, 23]  Nine months was shown to be superior to 6 months in patients with HIV, with peak benefit around 9 months. [36]  A significant disadvantage of a 9-month regimen is that compared with other shorter regimens, patients are more likely to not complete treatment. Possible alternative therapy (but not preferred) includes weight-based rifapentine once weekly, plus isoniazid once weekly, plus pyridoxine once weekly for 12 weeks (B recommendation). [1]

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