Core Curriculum on Tuberculosis, 2000
Treatment of Latent TB Infection (LTBI)
Regimens for Specific Situations
Contacts of Isoniazid-Resistant TB
For persons who are known to be contacts of patients with
isoniazid-resistant, rifampin-susceptible TB, a 4-month regimen
of daily rifampin is recommended. In situations where rifampin cannot
be used, rifabutin may be substituted. For HIV-positive
persons, a 2-month regimen with a rifamycin and pyrazinamide is
Contacts of Multidrug-Resistant TB
For persons likely to have been infected with a strain of M.
tuberculosis resistant to both isoniazid and rifampin, alternative
regimens should be considered. Alternative regimens should consist
of two drugs to which the infecting organism has demonstrated susceptibility.
Potential alternative regimens include either 6-12 months of daily
ethambutol and pyrazinamide or 6-12 months of pyrazinamide and a
quinolone (i.e, levofloxacin, ofloxacin, or ciprofloxacin). Immunocompetent
contacts may be treated for 6 months or observed without treatment.
Immunocompromised contacts (e.g., HIV-positive persons) should be
treated for 12 months. Persons receiving pyrazinamide and a quinolone
antibiotic should be monitored closely for adverse effects. Some
evidence suggests that the combination of pyrazinamide and ofloxacin
may be poorly tolerated. 6
All persons with suspected multidrug-resistant LTBI should be followed
for 2 years regardless of the treatment regimen.
Ethambutol at the usual dose is safe for children. The regimen
of pyrazinamide and ethambutol for 9-12 months is recommended for
children if the infecting organism has demonstrated susceptibility.
When pyrazinamide and/or ethambutol cannot be used, a combination
of two other drugs to which the infecting organism is likely susceptible
Persons with Fibrotic Lesions
Patients who have a chest radiograph suggestive of old fibrotic
lesions thought to represent previous TB, a positive tuberculin
skin test (>=5 mm), no evidence of active disease, and no history
of treatment for TB should be treated for LTBI. Acceptable regimen
- 9 months of isoniazid
- 4 months of rifampin (with or without isoniazid)
Patients who have a positive tuberculin skin test and radiographic
findings suggestive of healed, primary TB (calcified solitary pulmonary
nodules, calcified hilar lymph nodes, and apical pleural capping)
are not at significantly increased risk of TB. Their risk for progression
to TB disease and the need for treatment of LTBI should be determined
by other risk factors and the size of the tuberculin reaction.
Pregnancy and Breast-feeding
Isoniazid administered either daily or twice-weekly are
the preferred regimens for the treatment of LTBI in pregnant women.
Such women taking isoniazid should also take pyridoxine (vitamin
B6) supplementation. Although rifampin may be safe, there
are no efficacy data supporting its use in this population.
For women who are at high risk for the progression of LTBI
to active disease, especially those who are HIV-positive or who
have been recently infected, initiation of therapy should not be
delayed on the basis of pregnancy alone, even during the first trimester.
For these women, careful clinical monitoring and/or lab monitoring
should be conducted.
Breast-feeding is not contraindicated when a mother is being
treated for LTBI. Likewise, the amount of isoniazid provided by
breast milk is inadequate for the treatment of an infant. Infants
whose breast-feeding mothers are taking isoniazid should receive