it is recommended for those;

• close contact with a person with infectious TB
• positive tuberculin skin test reaction and an abnormal chest x-ray that suggests inactive TB
• a tuberculin skin test that converted from negative to positive within the past two years
• a positive skin test reaction and a special medical condition (for example, AIDS or HIV infection or diabetes) or who are on corticosteroid therapy
• a positive skin test reaction, even with none of the above risk factors (in those under 35)