title: Failure of isoniazid prophylaxis after exposure to isoniazid-resistant tuberculosis.
abstract: We report the failure of isoniazid chemoprophylaxis to prevent the development of active pulmonary tuberculosis and tuberculin conversion in contacts of patients infected with isoniazid-resistant strains of Mycobacterium tuberculosis. Although failure of isoniazid chemoprophylaxis has been reported rarely in contracts of isoniazid-resistant tuberculosis, the cases reported here as well as previous observations by others suggest that isoniazid chemoprophylaxis for contracts of patients with isoniazid-resistant tuberculosis may not be effective and that other agents must be considered. Initial chemotherapy of active pulmonary tuberculosis in contacts of known drug-resistant patients should be based on drug susceptibility studies in the index case.
mesh_terms: D000293:Adolescent; D000328:Adult; D000636:Aminosalicylic Acids / Q000627:therapeutic use; D004352:Drug Resistance, Microbial; D004977:Ethambutol / Q000627:therapeutic use; D005260:Female; D006801:Humans; D007538:Isoniazid / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D012293:Rifampin / Q000627:therapeutic use; D013183:Sputum / Q000382:microbiology; D013307:Streptomycin / Q000627:therapeutic use; D014374:Tuberculin Test; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000517:prevention & control* / Q000635:transmission
chemical_list: D000636:Aminosalicylic Acids; D004977:Ethambutol; D007538:Isoniazid; D012293:Rifampin; D013307:Streptomycin