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    Suggest treatment for syphilis

Posted on Sat, 15 Jul 2017 in Infections
Question: Brief Question : Is it possible to have syphilis with rpr positive(1:4) and test negative for fta-abs test and treponema pallidum antibodies EIA .
Detailed Question :
I am a 31 year old male.Last year i had a one time encounter with a female.After 3 months i got tested for all std's and syphilis rpr came back as positive with titer 1:4. The follow up test FTA-ABS and treponema pallidum antibodies EIA test came back as negative.

My questions are
1)Can anyone truly have/had syphilis and still test negative on fta-abs and treponema pallidum antibody EIA tests.
2)I took amoxicillin 500mg twice for 10 days after 90 days of the incident. Could it have caused the fta-abs and EIA to become negative.
3)I was sexually abused when i was 14 years old. I never got tested for that incident but it always stayed in the back of my mind.Could i have got syphilis from that incident.over the period of 16 years,i would have taken antibiotics multiple times. Could it have cured syphilis and so fta-abs is coming back as negative (even though rpr is positive with 1:4 titer).


Answered by Dr. Monika Dede 47 minutes later
Brief Answer:
Please see the detailed answer below.

Detailed Answer:
Hello!I have been through your question.

Regarding your concern, you should know that RPR is not specific for syphilis and could be positive and in other conditions. But false negativity of FTA and EIA are not known because they are specific for treponemal antibodies.

Furthermore, due to the possibility of false-positive results of RPR test, confirmation for any positive or equivocal nontreponemal test result (RPR positive like you have) should follow with a treponemal test such as FTA-ABS, or MHA-TP, or TPHA, and TPPA as well EIA.

So, the sensitivity of treponemal test FTA-ABS and EIA tests are very high and in this situation, I think the most probably you are negative for syphilis.

But I'd suggest retesting again for RPR in order to exclude false positivity.

Amoxicillin could be used to treat syphilis but is not the best choice.

Usually, nontreponemal tests (RPR-VDRL) become (nonreactive) negative (but not positive) with time after treatment even with amoxicillin but in some patient nontreponemal antibodies could persist some time for life. Usually, the treponemal tests could be positive for life even after treated infection.

So these facts may exclude the possibility to have been infected before.

I hope my answer helps you. Feel free ask further.

Above answer was peer-reviewed by : Dr. Arnab Banerjee
Follow up: Dr. Monika Dede 20 hours later
Thank you for the answer doctor.Could you please take a look at the below two questions

Q1)Below is the timeline about my last encounter in 2016

Feb 29th 2016 -->Had a one time encounter with a female.
Mar 15th 2016 -->rpr positive(1:2) and fta-abs negative
mar 24th 2016-->Treponema pallidum ab eia negative
apr 11th 2016-->Treponema pallidum ab eia negative
Apr 13th 2016-->rpr postive(1:2),fta-abs and Treponema pallidum ab eia negative
apr 28th 2016 -->Treponema pallidum ab eia negative
May 27th 2016-->started amoxicillin(not for syphilis but for an injury) 1000mg everyday for 10days
July 5th 2016 -->rpr positive(1:4) and fta-abs negative.

Is the above testing in line with the current syphilis recommendations.Should i have waited longer. I dont know what is going on. did i get syphilis from the last encounter.

Q2)As i stated earlier, i was physically abused when i was 14 years old. I did not get tested or took any medication immediately. During the last 16 years i must have taken antibiotics multiple times for

various reasons.If i had acquired syphilis from the abuse, the fta-abs and EIA would still have been positive (treatment or not). So i must not have acquired syphilis from this.Please correct me if i am

wrong.Below is an article from ncbi which states that in late(teritiary) syphilis even the treponemal tests come back as negative.


/quote/As in up to 30% patients nontreponemal tests may not be reactive, treponemal tests should be performed. However, 2–4% of patients with late syphilis will show negative results with treponemal tests

also. As the number of organisms are too low in late stages, polymerase chain reaction (PCR) technique may be a very useful test in establishing a diagnosis./unquote/

My question is, its been more than 15 years since the sexual abuse took place, i must be in late syphilis , that is why the rpr titer is too low (1:4) and FTA-ABS is coming back negative. Do you recommend a

PCR test for me.

Thank you in advance for the valuable advise
Answered by Dr. Monika Dede 19 hours later
Brief Answer:
Yes you could be in late syphilisis.

Detailed Answer:
Thank you writing back.
I am sorry for my late response.

Based on your history and the RPR titer results I think that you could be in late syphilisis (without symptomps and rpr positive with low titer).

So, based on this I suggest to meet an ID specialist and to start the treatment with benzatinpenicillini 1.2 milion UI im 2 doses per day , one day per week for 3 weeks.
After this treatment I suggest to do again RPR test.

I hope my answer helps you.

Above answer was peer-reviewed by : Dr. Nagamani Ng
Follow up: Dr. Monika Dede 4 hours later
last question doctor. Could i have acquired syphilis from 2016 encounter or from the physical abuse incident that took place 15 years ago. If i had acquired syphilis from 2016 encounter wouldn't the fta-abs and eia become positive. so i am guessing i got syphilis from the physical abuse that took place 15 years ago. is it possible to have rpr positive and fta-abs/eia negative ?

do you think the rpr could be a biological false positive ? CDC website states "Treponemal antibodies appear earlier than nontreponemal antibodies and usually remain detectable for life, even after successful treatment. " in my case it is reverse. non treponemal is showing positive and treponemal is negative. i am worried i might have infected my children because i share food with them and kiss them frequently.
Answered by Dr. Monika Dede 19 hours later
Brief Answer:
I think that you have been infected with syphilis before 2016.

Detailed Answer:
Thank you writing back.
I am sorry for my late response.

Yes is true that usually treponemal antibodies remain detectable for life but sometime as well nontreponemal antibodies could remain positive at that level or 1:2 or 1:1 for a long time or forever after the treatment. Usually we use RPR to measure treatment response and when a decline in RPR titer is evidence that treatment was successful.
I think that you have been infected with syphilis before 2016.

Based on your above mentioned data I think that usually, a nonreactive result on an TP-PA test will establish the biologic false positive diagnosis of a
positive nontreponemal antigen test .The specificity of the TP-PA test is as good as, or better than,the FTA-ABS test.
So, I suggest to do a TP-PA test to define better the diagnosis.

I hope my answer helps you.

Above answer was peer-reviewed by : Dr. Vaishalee Punj
Answered by
Dr. Monika Dede

Infectious Diseases Specialist

Practicing since :2003

Answered : 937 Questions


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