Advances in tuberculosis preventive therapy

Isoniazid preventive therapy is recommended for all tuberculin-positive, high-risk persons, especially HIV-infected persons and children who are close contacts of tuberculosis patients, and for some tuberculin-negative persons such as children who are close contacts of infections cases and HIV-infected persons. The recommended dosages of isoniazid are daily 5 mg/kg or twice weekly 15 mg/kg. In the United States, the recommended duration of isoniazid administration is 12 months for HIV-infected persons and those with abnormal chest radiographs suggesting inactive disease, 9 months for children, and 6 months for all other patients. Liver toxicity especially among persons more than 35 years of age and nonadherence with therapy especially among persons who are healthy and asymptomatic are limiting the impact of isoniazid preventive therapy. A 3-month preventive therapy with rifampin alone or in combination with isoniazid was as active as the 6-month therapy with isoniazid alone in HIV-positive and HIV-negative tuberculin-positive persons. Studies with the new rifamycin derivatives are in progress. Of these, rifapentine in combination with isoniazid given only once weekly has great promise for improving significantly this important control modality.