INTRODUCTION. To evaluate the efficacy of three regimens of prophylactic therapy for tuberculosis in HIV-infected patients with anergy. METHODS. Prospective, multi-center, randomized, comparative, and open clinical trial. Anergy was defined as absence of induration in response to three antigens (PPD, Candida albicans and parotiditis antigen) applied by the Mantoux method. Patients were randomized into one of the following prophylactic treatment groups: isoniazid for six months (6H), rifampin plus isoniazid for three months (3RH), rifampin plus pyrazinamide for two months (2RZ) or no treatment (NT). After completion of treatment, patients were followed up for two years.

This study is a controlled, open, randomized, multi-center clinical trial. The study was authorized by the Clinical Research Ethics Committee of all participating centers and informed written consent was obtained from all the patients included. The cutaneous anergy was defined by the absence of a reaction (0 mm) to skin reactivity tests with tuberculin, Candida albicans, and parotiditis antigens 72 hours after inoculation. The patients were randomzed into one of the following four groups: isoniazid for 6 months (6H), rifampin plus isoniazid for 3 months (3RH), rifampin plus pyrazinamide for 2 months (2RZ) or no treatment (NT). All of the participating subjects underwent a basal study that included clinical and epidemiological history, chest x-ray, hemogram, analysis of serum creatinine concentrations, uric acid, AST, ALT, alkaline phosphatase, and total bilirubin, as well as a CD4+ T-lymphocyte count.During prophylactic treatment, patients were evaluated every 15 days for the first two months and monthly thereafter. At each check-up it was determined whether or not the patient was following the treatment properly and whether there were any adverse effects. Therapeutic completion was defined as taking at least 80% of the total prescribed dosages.Chemoprophylaxis was discontinued whenever a patient requested to do so or for any of the following reasons: appearance of Grade 3 or 4 side effects that could be attributed to the drugs used in the study; increases in AST and/or ALT values of three times or more their basal values; development of TB; or diagnosis of any disease that made interruption of the treatment advisable.

Inclusion Criteria:

• HIV infection confirmed by ELISA and Western blot
• Age between 18 and 65 years
• Life expectancy greater than two years
• Cutaneous anergy defined by the absence of a reaction (0 mm) to skin reactivity tests with tuberculin, Candida albicans, and parotiditis antigens 72 hours after inoculation.

Exclusion Criteria:

• Presence of active tuberculosis
• Background of previous antituberculosis therapy or chemoprophylaxis
• Presence of symptoms or signs suggesting pulmonary or extra-pulmonary tuberculosis
• History of hypersensitivity to the drugs used in the study (isoniazid, rifampin or pyrazinamide)
• Aspartate-aminotransferase and/or alanine-aminotransferase plasma concentrations more than or equal to four times their normal values, total bilirubin more than 2 mg/ml, and/or creatinine more than 2 mg/ml
• Pregnancy
• Undergoing treatment incompatible with any of the drugs used in the study.