Antibiotics Interference with Syphilis Test. Need advice.

[WorriedFellowJ]

Hello Dr. Hansfield and Dr. Hook,

I would like to ask if antibiotics will potentially affect the syphilis test?
I did VDRL Test 85 days after potential exposure, result non-reactive.

2 days after exposure, I was prescribed with Inoflox 200mg for 4 days as preventive measures.

51 days after exposure, I had severe sore throat, I was prescribed with Amoxicilin 250 mg for 6 days. My sore throat still persisted and I was then prescribed with Zinnat for another 5 days.

I read in previous post, Amoxicilin if given early might prevent syphilis, but I took for sore throat and quite long after the potential exposure.

One thing that worries me, I read in some websites, Ofloxacin will mask Syphilis test or symptoms. And I think, Inoflox is Ofloxacin? How about Amoxicilin and Zinnat? My concern is all these antibiotics might mask the Syphilis infection, if I was infected from the exposure causing false negative in the test.

Need your advice on this, doctor. What should I do next?

[Edward W Hook, MD]

Welcome to the Forum.  You should believe your test results. You did not get syphilis.  Onoflox is a quinolone antibiotic, relate to ofloxacin, ciprofloxacin an other members of the fluoroquinolone class of antibiotics.  it has no activity against syphilis an certainly would neither prevent syphilis not in any way change the reliability of test results.

Likewise, taking amoxicillin more than a month (51 days the first time) after your exposure would not change your syphilis test result.  The Zinnat is a cephalosporin antibiotic which would not change the reliability of your syphilis tests when taken more than a month (in your case, almost two months) after a risky exposure either.

My advice- believe your test results.  You did not get syphilis and have no reason to doubt your syphilis blood tests. Take care. EWH

[Edward W Hook, MD]

Glad to help. EWH

[WorriedFellowJ]

Hello Dr. Hook,

Thanks for quick response. Have a great day.

[Edward W Hook, MD]

The results of your PCR tests show that you do not have chlamydia or gonorrhea at this time.  These tests are highly reliable.  If you were infected, the test would have been positve.  EWH

[WorriedFellowJ]

Hello Dr. Hook,

Thanks for your reassuring response and also some medical lessons on the antibiotics. You have helped me, I will indeed believe my Syphilis VDRL test result.

I have one last question, which I hope you can help. I'm not sure this will require to post in a new thread. If it is, please let me know, Dr. Hook.

Here goes my question: At the same time when I got tested for Syphilis VDRL, I also got tested for Chlamydia PCR urine test and Gonococcal PCR urine test. Negative results for both tests. Can I assume these 2 tests results are also reliable? Although I have taken the above mentioned antibiotics? The duration between the last dose of last antibiotic Zinnat and the testing day is around 20 days.

Thanks in advance, Dr. Hook.