I am a 41 year old man and I received protected oral sex from a sex worker in July 20th , i was really worried about getting something from this event so i took 200 mg of doxycycline an hour after. 5 days later i started experiencing intermittently groin and testicle pinch type pain specially after ejaculation. on July 29th (9 days later) I did the naat test for ghonorrhea and chlamydia and both test came back negative. I am really worried about a false negative due to the fact that i took a 200 mg dose of antibiotics 9 days before the exam. What are the chances that this is a false negative situation considering that i am still experiencing this symptoms a month later? Percentage wise what is the likelihood of this exam results to be accurate, Taking into consideration the antibiotic dose? i don't have any burning or discharge, but groin and testicle pain on and off that started a few days after that oral event. I'm really cocerned about Ghonorrhea specially which i know is the biggest risk in this situation.  

It was a mistake to take doxycycline after the event you describe. It was zero risk for chlamydia and near zero risk for syphilis, the only STIs reliably prevented after receiving oral sex. As for gonorrhea, absence of symptoms after 5 days by itself is strong evidence against gonorrhea. And your symptoms do not fit with any STI; they are most consistent with anxiety over the exposure. (Anxiety doesn't cause symptoms, but it can greatly magnify trivial symptoms or even normal body sensations that otherwise would be ignored or not even noticed.) Finally, antibiotics do not allow persistent infection with false negative tests. If infected, doxycycline or other antibiotic will cure the infection or not; if it doesn't, then gonorrhea will always cause symptoms. In other words, the combination of absence of symptoms plus your negative test results are 100% proof you do not have gonorrhea or chlamydia. And neither of these cause "on and off" symptoms of any kind, and never cause "groin pain".

So all is well and no further testing is necessary. I hope this information is helpful. Let me know if anything isn't clear.

HHH, MD