after treament of three penciline injection for three weeks I went for a test but results show positive,how can I get negetive results.

There are 2 types of tests used to diagnose syphilis (infection by treponema pallidum...a bacteria). Non-Treponemal tests (such as the VDRL or RPR) which are used for screening to find infected people and Treponemal tests (MHA-TP, FTA, TPHA) which confirm the diagnosis. After treatment, the levels of the non-treponemal tests will go down. They may go back to negative, but in many peolpe, especially if they were not treated in the earliest stages after infection, may remain at a low level positive. These tests can be used to determine the response to treatment and will rise again if a person fails treatment or gets re-infected. The treponemal tests (such as teh TPHA which you had) will generally stay positive for life, they are not useful to monitor response to treatment. If your RPR or VDRL does not go down then you have to be sure you have not been re-infected...have your sexual partners been treated? Other possibilities are that you were not treated with penicillin or you did not get the appropriate treatment for the stage of disease (people with later stages or with brain infection may require multiple shots or intravenous treatment respectively). Hope that helps.

Joe