PPD, is the skin test for screening, when it is negative, meaning mostly negative for infection. myth: BCG aka 卡介苗 can show PPD+, not really. This thing is not working as a vaccine, nor it will cause false positive in most people. Though most Chinese had it done, it is basically a joke. So Chinese people could have PPD negative even if they had BCG, indicating such population never had TB positive infections. In fact, a lot of Chinese don't have TB. So if anyone says Chinese people =PPD+ or any nonsense about most Chinese has TB, that person is a fxxxing racist. Sorry about the language. So, when it is positive, patients need QuantiFeron gold or CXR.he quantiferon gold is the blood test, rather new test comparing to CXR. There is another blood test, T-spot, similar thing. If the blood test is new, it means that the patient has the infection, then she/he will need further test if it is latent TB infection or TB disease. If negative, then infection unlikely. Notice, unlikely, none of the tests is 100% in medicine, bummer. Then the CXR, if it is positive then it is positive. So for latent and active TB, it would be quite obvious for active TB, lots of other symptoms, fatigue, fever, cough, shadows on CXR, sputum, positive sputum culture...... Then treatment: still the same old drugs like decades ago, isoniazid, rifampin, ethambutol, pyrazinamide. For latent TB, we usually use Isoniazid(INH) or rifampin. Be sure to take B6 when using Isoniazid to avoid Side effects. Rifampin may cause red urine or tears, interesting. Both drugs are well tolerated by themselves, only might have drug-drug interactions when taking other meds at the same time. Make sure your doc knows about that. Otherwise, definitely don't miss the follow-up appointment. For CXR radiation, honestly, I feel people are so overacted to it, as for adults, extra 1-2 films really are nothing. People get 2 CXR equivalent radiation from the person sleeping next to them each year. I always joke about it: everyone should have a CT in the ER, it would reduce the cost tremendously in total and increase the efficiency.