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Antibitotic Effectiveness

Hi Doctors,

I am a heterosexual guy and received unprotected fellatio on Sunday (yesterday) outside of my relationship in a stupid drunken state. My new full time partner and I have just done a full STI check with a reputable online provider and are about to take a course of doxycline for Ureaplasma infection (I know that this is probably pointless but my partner wants to).

My question is if i have unprotected sex with my partner this week and we take doxycycline will it be safe to assume that the antibiotics will kill anything I may have picked up from yesterdays encounter that could go on to cause NGU - eg. normal oral bacteria etc and that you don't need to wait two weeks after an event for antibiotics to work? I will obviously test for Chlamydia and Ghonnoreah separately in a couple of weeks but just wanted to check that doxycline would work immediately - eg. if I infected my partner with something tomorrow and she started taking antibiotics the next day they'd work.


Thanks Doctor.
3 Responses
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239123 tn?1267647614
MEDICAL PROFESSIONAL
You entirely misunderstand the "normal oral bacteria" business.  Nobody would ever recommend treating for these bacteria after an exposure without symptoms.  That such bacteria may cause some cases of NGU is a theory, nothing proved -- and anyway, because the bacteria are normal, probably they would do no harm in a partner's genital tract.  (Except when NGU is caused by chlamydia or Mycoplasma genitalium -- which are rarely if ever acquired by oral sex -- it appears to be harmless in affected men's sex partners.)

You don't need to wait 2 weeks after an exposure for gonorrhea/chlamydia testing.  Those tests are valid any time more than 2-3 days after exposure.  (Some experts say a week to be safe, but that's for chlamydia -- which can be ignored in your situation.  For gonorrhea, 2 days wait is plenty fore sure.)

I recommend you drop all consideration of antibiotic treatment and instead wait for testing plus an examination professionally if you develop symptoms.  In any case, I will not help you with advice about treatment that I don't recommend, so I won't say more about it.

"do you mean that if you had received unprotected fellatio you would not have bothered to test (unless you had symptoms of course) and this is due to the low risk?"   Yup.
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Avatar universal
Sorry Doctor. I take on board your comments. I probably need to be clearer, the STD panel test was taken last week before this incident yesterday hence the need to re-test for Chlamydia and Ghonnoreah in a couple of weeks.

My concern is of what you refer to on this site as 'normal oral bacteria' that could be of harm to my partner if I pass an infection to her - given you cant test for these 'normal bacterias' my thinking was that the doxycline  we were going to take for ureaplasma would eradicate it in both me and my partner especially as I'd read on this site that doxycycline was highly effective against NSU.

It would be appreciated if you could confirm:

- that doxycline would be a highly effective antibiotic against 'normal oral bacterias' hence it is often prescribed for NSU?

- that if an infected person took antibiotics the day after being infected the antibiotic would work.

- Finally, just to clarify, do you mean that if you had received unprotected fellatio you would not have bothered to test (unless you had symptoms of course) and this is due to the low risk?

Thanks and apologies for the confusion.
Thanks and apologies for the confusion.



Helpful - 0
239123 tn?1267647614
MEDICAL PROFESSIONAL
Welcome to the forum.

I agree with your comment about treatment to eradicate or prevent Ureaplasma is pointless.  Ureaplasma is a normal bacteria in the genital tract and rarely causes disease; and if you or your partner have it, and if the doxycycline eradicates, it will only be temporary.  Ureaplasma almost always reappears after treatment.  Anyway, Ureaplasma is not carried in the oral cavity, so you can't catch it by oral sex.  Assuming you are doing this because Ureaplasma showed up on your online STD testing panel, it's something you (and probably your partner) have had all along and will never do harm.

And may I ask why you are being tested "separately" for gonorrhea and chlamydia?  Not done in the panel you already had?  In any case, it would be pointless to test for them after taking doxycycline, which would cure them if you had either one, and would guarantee a negative result.

I cannot condone you treating yourself for this. Overuse of antibiotics has had horrendous effects on resistance of many bacteria, increasing the risk of life threatening infections in the population at large.  It is exactly use like you propose that is largely responsible.

On top of all that, why doxycycline?  There would be better choices to eradicate the STDs to which you might have been susceptible from a single episode of oral sex.  A single 1 gram dose of azithromcyin, for example.

Please drop this plan. Continue unprotected sex with your regular partner; assuming ureaplasma is the only potential issue that shows up on your joint STD testing, that's no reason for worry.  If I were in your circumstance, I would not have been tested, would not treat myself, and would continue unprotected sex with my wife without worry.

Regards--  HHH, MD
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