please help

i am taking metronidozole right now and i had rocephin and zithromax last night for what was prescibribed as acute uretherits probably due to an std. i have plans to take an hiv dna test. will any of these meds effect the results of this test and if so how long should i wait to get tested?

[Edward W Hook, MD]

None of these medications will affect the performance of an HIV DNA test, nor an HIV antibody test.

I should add however that, in general we do not recommend HIV PCR testing for diagnosis is HIV infection for several reasons.  While the PCR is likely to become positive more quickly than other antibody detection tests (i.e. usual blood tests), at the present time the blood tests are becoming more and more sensitive and detecting infection earlier and earlier so that the time difference in detection between PCR test and antibody detection tests is becoming smaller and smaller and at present is, in general only a week or two.  In addition the time course over which the PCR tests become positive is less well described than for the blood tests and, as a result, it is difficult to make a definitive statement on what a negative PCR test means at any time within a few weeks of exposure to a HIV infected or possibly infected partner.  PCR tests are also more expensive than regular antibody tests.  Finally and most importantly, the false positive rate for PCR tests (i.e. a positive result in persons who do not have HIV) is higher than for blood tests.  Each of this on this Forum have seen a number of people who were worried needlessly because of false positive tests. For all of these reasons, we rarely recommend testing for HIV diagnosis using PCR.  EWH