I have recently been treated for bladder infection/uti following cystoscopy for kidney stones (Keflex 500mg 3x daily for 10 days). 24 hours after completion of antibiotic, I received fellatio and performed cunnilingus on new partner (not my spouse). Do not know if she is infected with anything but unlikely since her STD-IQ is high due to professional field. My questions are as follows: (1) would the antibiotic remain protective against infection with gonorrhea/ngu (fellatio) and/or gonorrhea/syphillis (cunnilingus)? (2) If not, would my infection risk be higher than usual due to previous illness? Thank you.

Let me start by pointing out that, in addition to the low risk of your new partner, the sex acts that you participated in are low risk for acquisition of STI.  Pharyngeal infections are rarer than genital infections so that the likelihood of acquiring any STI from receipt of oral sex is low.  When such infections occur, Gonorrhea and non-gonococcal urethritis (NGU) are the most likely STIs to follow receipt of oral sex.  There is virtually no risk to you for Syphilis or HIV.  The keflex you took would not be in your system at the time of exposure and thus it would not offer any protection to you from the very small risk of infection that would follow this act.  Your recent cystoscopy would not be expected to increase your risk for infection ten days after the procedure.

As for your cunnilingus.  Again, given your partner's low risk for infection and the sex act, I would not worry about acquiring an STI.  Even with infected partners, acquisition of STIs from performing cunnilingus is quite unusual.  Were any STI to follow yourcunnilingus, the most likely infection would be Gonorrhea and again that risk is very, very low.

So, what to do.  Personally, from what you have described, unless penile symptoms occur in the 5-7 days after your exposure, I would not seek testing.  If you are worried however and choose to seek testing, the most important tests to seek would be a urine test for Gonorrhea and Chlamydia (NGU) and perhaps a throat swab for the same orgais s.  I would not worry at all about HIV. Syphilis.

I hope this I formation is helpful.  EWH