For context five months ago I received brief unprotected oral from a mid range CSW (not street walker but not agency) the person seemed in good health and condoms were present in the room (which suggests they are used at least some of the time). I had no symptoms after and at the time believed gonnereah was my main concern so after 14 days of celebacy I resumed sex with my regular partner. My rationale is the chances of infection and being asymptomatic for this condition were remote especially given occurrence and transmission in this way is also rare and the chances of being asymptomatic is also unlikely.

However since then I have become increasingly aware of oral Chlamydia and it's sent me into a bit of a panic (hence why your forum has been so helpful). I understand it is less common than oral gonnereah but my question is this considered in a promotional sense given Chlamydia is the more common infection (especially in the UK where I believe it's 2-3x more common than gonnereah). So whilst it's uncommon it's still a higher number or is this taken into consideration when you both say it's rarer than gonnereah in this context.

The logical being in me suggests my risks of Chlamydia are still very low and even if infection was present and therefore still highly unlikely to be transferred from throat to penis is this a fair assesment.

Oral chlamydia is rare. Chlamydia trachomatis does not take well to the pharynx or mouth; the large majority of oral exposures to it (almost entirely by performing oral sex) do not result in infection taking hold. Second, even when it is detected in the throat by nucleic acid amplification testing (NAAT, a test for chlamydial RNA) it is present in very small amounts; culture (i.e. growing the organism in the lab) usually is negative. That is, chlamydial RNA is present but often not live organisms that can be transmitted to partners. And even these positive results generally turn negative quite soon, usually in a couple of weeks. Either a transmitted infection has been rapidly cured by the immune system; or there never was an infection at all, only exposure that didn't take hold. And although chlamydia causes 30% of nongonococcal urethritis (NGU) in males, that's only for men who have had vaginal or anal sex. Chlamydia almost never causes NGU in those whose only exposure was insertive oral sex. And it is very rarely transmitted at all by cunnilingus. Finally, unlike oral gonorrhea, oral chlamydia has never been known to cause symptoms -- no sore throat, no cough, no sniffles, no fever -- nothing.

However, another aspect of oral chlamydia has come up with evolving research. It sometimes probably results in the gastrointestinal tract being colonized. And as the organism passes, it may result in rectal infection even in persons who have not received anal sex. And from the rectum, chlamydia can easily be transmitted to a woman's genital tract by local contamination -- which might occur years later, with the organism surviving in the GI tract all that time. This is now believed to explain at least some cases of detection of chlamydia in women who have not been sexually active or otherwise at risk for many years. 

For the reasons above, CDC and most similar agencies -- including most UK GUM clinics -- officially recommend against testing for oral infection. However, chlamydia and gonorrhea testing almost always are done together, and therefore occasional patients test positive for oral chlmaydia. And because chlamydia is far more common than gonorrhea, the number of positive may be greater -- as your have found in searching abut UK data. But as implied above, it usually isn't causing any problem, is rarely transmitted to partners, and soon goes away without treatment. However, when someone does test positive, treatment usually is given, to be on the safe side. But usually little harm would come if testing had not been done or if not treated.

Now to your specific questions:  The chance you acquired urethral chlamydia from your oral sex exposure 5 months ago is nearly zero. And if you did, it likely was gone within two weeks. All things considered, it is very unlikely your regular partner is at risk for chlamydia on account of these events.  That's a long-winded reply, but essentially I am confirming that "my risks of chlamydia ares till very low and...unlikely to be transmitted from throat to penis."

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

Thank you for your time to respond to this in detail. So again just to confirm in my head 

Oral Chlamydia is indeed rare

When it does happen it's often not able to transmit

Even if it does make it to a new host often it's diminished in potency enough that the new hosts immune system can be more effective against it quickly 

I saw the CDC don't appear to believe it's a major concern for public health. I guess with the prevelance of Chlamydia and the fact I'd imagine most oral sex is unprotected (and it's common) if it was at all a quantifiable risk it wouldn't take much to push the needle significantly increase cases so the CDC probably wouldn't have this stance without good reason.

In crass terms I am seeing this like an accumulator bet of  3 or 4 long odds results so the bet hitting  is not impossible the bookie isn't losing sleep about it.

I'm unaware of any CDC statement I would interpret as oral chlamydia as "a major concern for public health. I'd be happy to comment if you'd like to point me to a particular publication or online information about it. Otherwise your understandings are correct.

Best wishes and stay safe.