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Dr. Andrew Rynne
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Dr. Andrew Rynne

Family Physician

Exp 50 years

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Is negative blood report for syphilis 5 weeks post exposure conclusive?

Answered by
Dr.
Dr. S. Murugan

HIV AIDS Specialist

Practicing since :1974

Answered : 2840 Questions

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Posted on Sat, 10 Sep 2016 in Sexually Transmitted Diseases
Question: Received unprotected oral sex from femal stripper in midwest USA. Was afraid of the possibility of syphilis. Took 2 gram does of azithromycin 8 days after exposure to prevent a possible infection. Also took 8 days of amoxicillin (read since it is a form of pennicillin it would prevent syphils from incubating) for 8 days 2 pills a day 500 mg. 5 weeks 2 days past exposure had blood test for syphilis. Negative. What are chances I have syphillis since I took antibiotics and had a negative test at 5 weeks 2 days
doctor
Answered by Dr. S. Murugan 2 hours later
Brief Answer:
You are unlikely to have Syphilis.

Detailed Answer:
Hi,
Welcome to HCM.
Thanks for posting your query.
The risk of syphilis through oral sex is far less unless the individual (sex partner) had an obvious sore in her lip or mouth or any other erosive lesions inside the mouth. Bacterial STDs are not so common nowadays. So your fear for syphilis through oral sex is baseless.
Tab.Azithromycin and Cap.Amoxycillin are having Treponemicidal effect. So this could definitely abort the disease (syphilis) if any.
Regarding the test for syphilis, it will become reactive 4 weeks after the exposure in presence of the disease. You had the test 5 weeks after the exposure. There is possibility of delay in test becomes positive after taking some Treponemicidal drugs, but more chances for aborting the disease (syphilis) if any, as you had adequate dosage of prophylaxis.
Not to worry.
Dr S.Murugan

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. S. Murugan 15 hours later
Thank you. The experts at medhelp said amoxicillin is very effective in preventing syphilis to take if taken recently after possible exposure. Do you agree?
Also I think I will have another test at 6 weeks to be safe. Will this test be conclusive? I finished the amoxicilin 23 days before test at 6 weeks and azithromycin 36 days before the test at 6 weeks. Will the antibiotics still affect the test if they have been completed 23 and 36 days before the test? Thanks
doctor
Answered by Dr. S. Murugan 1 hour later
Brief Answer:
Syphilis will got aborted with Amoxycillin and Azithromycin

Detailed Answer:
Hi,
Welcome back.
I quite agree that a course of Cap Amoxycillin will definitely abort the syphilis, if any.
As a prevention measure such along course of antibiotics are not necessary. Even the therapeutic dose for early syphilis is not more than 15 days. A week course is enough as a prophylactic dosage to abort the syphilis. 23 days and 36 days are not necessary. If the disease got aborted then the test will always be nonreactive only.
Dr S.Murugan
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. S. Murugan 5 minutes later
Only took amoxicilin for 8 days 500 mg twice a day. Also took 2gram dose ar once of azithromycin. I'm afraid those antibiotics cussed a false negative at 5 weeks. Should I re rest at 6 weeks
doctor
Answered by Dr. S. Murugan 6 hours later
Brief Answer:
You need no further test for Syphilis.

Detailed Answer:
Hi,
Welcome back.
I feel you don't need any more test for Syphilis.
The risk is remote.
Your tests for syphilis 5 weeks after the exposure is nonreactive.
The drugs you had taken already was sure to abort the infection, if there was any.
Dr S.Murugan
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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Follow up: Dr. S. Murugan 56 minutes later
Thank you. This is the last question. I promise. Haha
Saturday I masturbated 2 times with out lube and it hurt a little bit after. I woke up Sunday morning and had a small tear in the shaft of my penis. It has completely scabed over in 2 days and is almost healed. Would a syphils chancre scab over and heal in 2 days? I visited a primary care physician and he said it just looked like a superficial cut from masturbsting a few times and not a chancre. He also believed the antibiotics I took would of prevented syphilis from incubating. Thanks
doctor
Answered by Dr. S. Murugan 2 hours later
Brief Answer:
You are unlikely to have Syphilis

Detailed Answer:
Hi,
Welcome back
Syphilitic ulcer would not heal within two days. Syphilitic chancre has special characters and never look like a scratch. Not to worry about Syphilis.
Dr S Murugan
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
doctor
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