non-Gonococcal / non-Chlamydial urethritis from oral sex

[Billy1962]

I am a male in my early 50’s.  I periodically engage the services of female sex workers.  When I do so, I receive unprotected oral sex and have protected intercourse.  Over the years, I have had several episodes of Urinary Tract Infections, that appear to be associated with these activities.  The typical scenario is that, anywhere from 2-7 days following one of these encounters, I will experience a small itching or stinging sensation in my urethra.  This will then be followed by the appearance of a whitish urethral discharge.  This discharge will continue for about a week.  On several occasions, I have visited a clinic, was given a single 1000 mg dose of Azithromycin, no tests were performed, and the symptoms cleared.  On one occasion, I was given this treatment, but also tested for Gonorrhea/Chlamydia.   The symptoms went away and I was later told I had tested positive for Chlamydia.  Another time I had these symptoms, did not get any treatment, but was tested for G&C.  My tests for both Gonorrhea and Chlamydia came back negative and the symptoms cleared, untreated.  I have discussed this with a friend, who engages in the same activities I do, yet has never had these symptoms.  I have tried to research this on the internet.  The information I have found leads me to several questions:
1) Is it possible to acquire a Chlamydia infection from receptive oral sex?
2 ) Is it common to acquire bacterial infections from receptive oral sex?
3) Is it possible that the cause of my infections is viral and not bacterial?
4) My experience has been that, whether or not I take any antibiotics, the symptoms clear in about a week.  Am I just as well off not taking antibiotics?
5) Why do I have this problem, when my friend doesn’t?  Is this common, or do I just have a “weak” urethra?

Thanks for your response to this- I have found your replies to others to be quite practical and level-headed.

[Vance2335]

Not really sure, the mouth holds so many different bacteria.

[Billy1962]

Thank you for taking the time to give me your opinion.  Your answers are what I would think myself.  I especially appreciate your suggestion in number 5.  It's funny- that is probably the advice I would give to someone, but I never applied it to myself.  While I use condoms for intercourse, I have avoided using them when receiving oral sex, as I felt that the risk from this was sufficiently low.  However, the fact is that  I have gotten infections on a number of occasions.  I have been focusing on the why, more than just accepting it and stepping up my level of protection from it.  It has been a relatively low rate of incidence, I am guessing about once every 15-20 partners. If I am not having any sexual contacts, I do not get any Urinary Tract Infections, however, if I receive unprotected oral sex there is about a 5% chance I'll pick up a non-gonococcal, non-chlamydial  UTI.  It just seemed to me that if this was this common, you would be hearing a lot more about the dangers of unprotected oral sex. It's also funny that there doesn't seem to be much about this appearing on the internet.  Do you know what types of bacteria would be involved here?  I would suspect it would be something that is typically found as part of the mouth flora. Maybe Enterococcus?

[Vance2335]

1. Possible but rare
2. More common then chlamydia but still low risk
3. I would say most likely bacterial
4. I would always treat it
5. I can't say, but I will advise to use condoms for everything