Active tuberculosis in children who received INH chemoprophylaxis

Twelve children who developed active tuberculosis even after receiving isoniazid (INH) chemoprophylaxis were seen at Tokyo Metropolitan Children's Hospital from 1982 through 1991. All cases received INH more than 9mg/kg/day, except for one case in which the amount of INH administered at the referring hospital was unknown and Streptomycin was administered together with INH. The age of starting INH prophylaxis ranged from 2 months to 13 years, and the age at which clinical symptoms and/or laboratory evidences of active tuberculosis were first manifested ranged from 4 months to 18 years. Five patients developed active tuberculosis after the completion of chemoprophylaxis and patients during chemoprophylaxis, with the first presentation ranging from primary complex (seven), chronic pulmonary tuberculosis (two), tuberculous meningitis (two), and tuberculous pleuritis (one). None of the Mycobacterium tuberculosis resistant to INH was isolated.Reviewing these patients, eleven cases had at least one of the following factors: (1) age less than two years old (2) infectious sources expectorated more Mycobacterium tuberculosis (3) delay in starting INH. Above factors should be considered in initiating INH chemopro phylaxis and subsequent follow-up of the patients.