You should get a Mantoux skin test because it is the easiest way of identifying if there is TB bacteria in the body. If the results are positive then you will need a chest X ray to confirm if you have the active form of the disease.

Most likely you do not have a TB infection. However, someone with the active form of the disease may not show a reaction to the test. If a person does have symptoms that indicate active tuberculosis such as unintended weight loss or coughing blood then they must go for further testing.

If you have been exposed to someone who has active TB and you obtain a negative result then it is likely that you do not have the TB bacteria in your body. Therefore you would not need to take any medication. 

Yes, the BCG vaccine usually does not protect everyone against TB. Vaccinated people can still become infected with the TB bacteria and develop the active form of the disease. So you would still need a TB skin test.

You must take isoniazid for at least 9 months to completely destroy the TB bacteria. You may think it is hard to keep on taking this drug especially when you do not feel sick but it is essential you continue to take it until the time period is over. If you do not, you run the risk of the TB bacteria becoming active and resistant to the medication.

Most people who take it normally do not have side effects. However if you do notice any changes in your health or appearance while taking Isoniazid alert your Doctor immediately.

No. If the first chest X ray does not show any sign of active TB disease then it does not need to be repeated, especially if you are not showing any symptoms of the active TB disease.