[Question #5599] MSM with another possibly on PrEP

21 months ago
I am a gay, 42 yo male who had a sexual encounter [being the bottom] with another male on May 29,2019.
 He is a 47 yo Hispanic male who stated he is on PrEP and recently tested in January. Not sure if he was claiming the truth about being on PrEP but he seemed to know sufficiently about Truvada and having to have his liver tested every 6 mos for the PrEP pill.    We engaged in anal/oral sex. I bottomed, used a condom at first but we had brief anal [unprotected] for about 10 min [without ejaculation].    I was tested  via Quest Diagnostics with a 4th Generation HIV ab/ag test on Tuesday, June 25,2019...approximately 27 days later.  The test result was negative [received results today: 6.27.19].  Out of wanting absolute surety of the event I scheduled an HIV RNA test as well when I had the blood drawn for the 4th Gen. Test ...and results will not be available until Monday, July 1, 2019.

Questions:
1. Would the HIV ab/ag test have been positive by now? [approximately 27 days later]
2. If both tests [HIV ab/ag and RNA]  are negative, will I need retesting?
3. I was on Cefdinir 300mg  2x /day for an upper respiratory infection from 5.30-6.9 as well as Doxycycline Monohydrate 100 mg 2x a day for 10 days because the Cefdinir didn't see successful......Would the happenstance of me being on those two antibiotics over 20 days have inadvertently healed any bacterial STI's like gonorrhea, chlamydia or syphilis?
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
21 months ago
Welcome to the forum. Thanks for your confidence in our services.

Few people lie about HIV status when asked directly, or are likely to be untruthful about being onj PrEP. And even if he had HIV, Truvada ostensibly for PrEP (but actually for known HIV infection) reduced the chance of tranmission by at least 99%. And your negative test at 27 days is aournd 98% conclusive. So let's calculate the odds:  Chance your partner has HIV, given his history, say 1 chance in a thousand. If he had HIV, chance he was infectious despite Truvada, 1%. If he had HIV, transmission risk for a single episode of receptive (bottom) unprotgected anal sex, around 1 in 300 (but I'm going triple that chance to 1%, i.e. 1 in 100, for the following calculation. Chance of your test missing HIV, 2% (1 in 50, or 0.02). So the chance you have HIV is in the range of 0.001 x 0.01 x 0.01 x 0.02 = 0.000000002, if I correctly counted the zeros. That's 2 in a billion, or 1 chance in 500 million. That is, zero for all practical purposes. And even if some of my estimates are way off, maybe 1 chance in say 5 million? Accordingly, I would not have recommnended you be tested even once for HIV, and I certainly would not have recommended the RNA test on top of the AgAb test. You can be sure the result will be negative.

Those comments pretty well answer your first two questions, but to be explicity:

1) Yes, 98% chance your AgAb test would be positive if you caught HIV.

2) For sure no further testing when you get the negative RNA result

3) Those antibiotics were 100% protective against gonorrhea, chlamydia, and syphilis. Don't waste any more money on testing for any of them.

I hope these comments are helpful. Apologies if the opening comments sound like a lecture -- I don't mean them that way, just for reassurance. Let me know if anything isn't clear.

HHH, MD
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21 months ago
Didn't seem like a lecture at all....but something I would have likely needed anyways. 
I appreciate your candid response and the detailed answer..it is much appreciated.
Thanks for your knowledge and availability in answering these questions on this site.
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
21 months ago
Thanks for the thanks. I'm glad to have helped. That's why we're here.---
21 months ago
Just as a follow up..the HIV RNA by TMA result was negative. Per the lab paperwork, "HIV -1 RNA was not detected in the lab specimen".
The RNA test by TMA was used with a Aptima HIV-1 RNA Qualitative Assay by GenProbe.

Thanks for the professional reflection on my case. I'm glad I can move past this incident with your assistance.

 I will also look into PrEP with my MD as I move forward with sexual safety. 
H. Hunter Handsfield, MD
H. Hunter Handsfield, MD
21 months ago
Glad to hear those results. Take care and stay safe.---