Again, unprotected oral sex only, never any anal penetration of any kind.

Yes, HIV transmission by oral sex is very rare, and may not occur at all in the oral to penile direction. One calculation, published a few years ago by CDC, is that if one partner has HIV, the average risk penile to oral is 1 in 10,000, 1 in 20,000 in the opposite direction. These figures are equivalent to giving or receiving BJs by infected partners once daily for 27 and 55 years, respectively.

True for gonorrhea and NGU, but not chlamydia -- i.e. sentence 2 is correct. Chlamydia transmission by oral sex is too rare, and too few studies, to permit a statistical estimate, but I would guess it's well under 1 chance in a thousand. Chlamydia doesn't often take hold in the throat, and of course an infection that isn't present cannot be transmitted. Also, FYI you don't mention genital herpes due to HSV1, which among the higher risks for oral sex. But still uncommon after any single exposure.

"Other thoughts":  Your symptoms in fact did not suggest NGU ---- i.e. you don't describe anything that sounds like urethritis symptoms, however slight. NGU rarely causes urinary discomfort at all, in the absence of abnormal discharge. Discharge is the only symptom that is particularly suggestive of NGU. I would have argued against treating you with ciprofloxacin, and I doubt it made any difference. As for HIV, your symptoms there also are too subtle to be meaningful. HIV would never cause only a single enlarged lymph node, for example. However, you should be tested for HIV. Not because you are really at risk; from a strictly medical standpoint, I wouldn't recommend it. However, once people start to fear HIV, typically their concerns continue regardless of professional advice based on probabilities and statistics, no matter how expert the source. In this setting, a negative test result typically is more reassuring than expert opinion. Enough time (4+ weeks) has passed for a conclusive result with an antigen-antibody (4th generation, "duo") HIV test.

Final advice:  Since you say nothing about your partner's HIV status, I assume you didn't ask. That was a mistake. Even with low risk exposures like fellatio, every man contemplating sex with other men should first discuss their mutual HIV status, and probably defer any contact at all with those who are positive and not on treatment, don't know, or seem evasive about it.

In the meantime, stay mellow. I'm confident you don't have HIV or any other STD from the exposure a few weeks ago. But let me know if anything isn't clear.

Best wishes and stay safe--  HHH, MD

My partner claimed to be "disease free",  but I did not ask about HIV specifically, but I assumed, however stupid that may have been, that he was clean of all infections.

As for being tested for HIV, I would rather not be tested unless medically necessary, so I'll ask you directly.  Were I to walk into your clinic, would you recommend I be tested for HIV?

Thank you for the statistics info on chlamydia as well.  That makes me feel a lot better too.

One question I forgot in my original post:  does Cipro kill any bacterial STIs?  

Would I recommend HIV testing? Yes, in that 1) CDC recommends that every adult be tested for HIV at least once, regardless of risk (including, for example, the average no-risk housewife); and 2) all men having sex with men should be tested from time to time, pretty much independent of specific risky exposures. However, neither of these is rigid, especially if this was a one-off event, with no other male-male sex. While I would offer testing to men in your situation, I would present it as entirely voluntary.

Cipro is not recommended for any STDs. It has zero effect on syphilis, and has only weak and often unsuccessful effect against chlamydia. It works against most gonorrhea in the US, although some strains are entirely resistant and therefore it is not recommended for routine gonorrhea treatment. But this doesn't alter my opinions and advice above; they would be no different if you hadn't been treated at all.

This was definitely a one-off thing, and completely out of character for me.  I've learned through this that it's really just not worth the anxiety of it all!

For my final follow-up, I didn't ask specifically about syphillis in my original post, but I also understand from this forum that it is extremely rare in oral sex?  How rare is rare?  I didn't see any lesions or anything like that, but if the sores were in his mouth, I suppose I would have no way of knowing that.

I will think about testing, but I'm confident now that I am in all likelihood in the clear.  I checked out some of my state specific statistics, and that further reassured me.  As it turns out, my state ranks quite well nationally in STI rates, etc.

I truly appreciate the service you and your colleagues offer on this forum.  It's most definitely a very valuable tool for people to have access to experts in this area.  

That completes two follow-up comments and replies included with each question, and so I'm closing this thread. Take care and stay safe.