Two questions in testing.

1).  I am male and became sexually active with men starting end of ‘98  into 1999, being sexually active I would occasionally be screened for HIV, Gonorrhea and Chlamydia but for some reason never tested for syphilis, never came to mind.  I was first tested for syphilis in 2008 due to a partner notification of exposure.  I ended up having 3 RPR in 2008 all negative and have included RPR as part of routine screening since when sexually active.  My question is whether RPR test would of picked up infection 9-10 years earlier?  In the event I was infected early on.  

2) More recent history I got an RPR test and HIV test as part of routine screening,  however I later remembered I was on an antibiotic for respiratory infection when tested,  I don’t recall the exact antibiotic.  Also, back several years ago I was treated off and on for prostatitis with cipro primarily and sometimes doxy...I could of been on those when screened.  So to your knowledge does being on an antibiotic mask or interfere with the RPR blood test?  Causing a false negative? 

Thank you 

Second question first:  There are no medications, including all antibiotics, that interfere with syphilis blood tests. Of course some antibiotics can cure syphilis (even if prescribed for something else in someone with undiagnosed syphilis), and that can make the RPR negative. That doesn't mean the test is falsely negative -- it means the infection was cured. For example, doxycycline is active against syphilis -- in fact, it is the treatment of choice in people who are allergic to penicillin. In any case, your negative RPR results were true and accurate:  they indicated no active syphilis at the time the tests were done.

First question:  Your negative RPRs starting in 2008 were reliable, i.e. you did not have syphilis at the time you were tested. It is conceivable you acquired syphilis in 1998-99, but if you did, you no longer had it when the RPRs were done.

Other blood tests are available that remain positive for life, even after syphilis has become inactive or has been cured with antibiotics. If you remain interested, you could be tested now; just ask a lab (or your doctor) for a syphilis enzyme immunoassay (EIA) test. (Some labs refer to it as an IgG/IgM test.) If negative, it will mean you never had syphilis. However, such testing really isn't necessary unless you are interested:  from the RPR results, you can be sure you do not currently have syphilis.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

I would like clarification with your answer to my first question.  In your answer you said ‘even after syphilis has become inactive OR cured with antibiotics’.  Am confused about an inactive state, does that mean can go dormant and then become active again?  I think the heart of the question was if I was infected let’s say 1999 or 2000, but did not do RPR until 2008.  Could the infection have progressed to a late latent or tertiary stage where it is inactive and not picked up on RPR in 2008 and I still have it and could progress to do harm decades later?   I would think either you are cured or not, confused on inactive.  I gather the jist from your entire response is if I have negative RPR, I don’t have syphilis, but that part confused me.  Also, I would don’t want to do any further testing for interest with an EIA  if confident I am not infected.  I have not been sexually active since last negative RPR.  It was more that big gap years ago and reliability of RPR missing a late stage dormant infection.  

Thank you 

That concludes this thread. I hope the discussion has been helpful.