Hello Charlyn, Thanks for posting on HCM, Positive mantous test or PPD does not directly mean that you have an active TB infection. It could mean that you were ones exposed to TB but did not develop the diseases. Normally most immunocompetent people are PPD positive especially in high TB endemic regions. They are also false positive, true positive, false positive and true negative test results. These are determined by the size of the PPD and in your case, you probably had a false positive result (which signifies you are negative). More over, the decision to place you on antiTB drug ( like isoniazid) should have been complemented with some clinical signs like presence of a pulmonary infection, lymphadenitis, POTs diseases and other signs that they might be a chronic infection that requires TB remedy. If you were not manifesting any signs of active TB (like night sweats, intermittent fever especially at night, signs of infection etc) then the decision to place on isoniazid based on positive PPD is wrongly justified. Well after completing the treatment of TB, PPD could still come positive but active TB infection has been eradicated, therefore we still come to the point that taking isoniazid and evaluating directly with PPD is not properly justified. The only direct test is determining the presence of acid-fast-bacilli (AFB) myobacterium in either sputum, biopsy of a mass or lymph node etc. I sincerely wish you the best Dr Nsah