Patient: Could exposure to strep while taking antibiotics for strep affect treatment? I’m on my second round of antibiotics for strep throat (first on penicillin and now on cephalexin) due to a relapse; I took my first dose of my second round of medicine Tuesday night and have taken two doses yesterday (Wednesday). Sore throat is pretty much gone by now. I chalked my relapse up to improperly sterilizing my dental retainer that I’m to wear a couple nights a week. Last night, I was running out the door and soaked my retainer in an alcohol/hydrogen peroxide mixture for about 5 minutes. Then a few hours later when I returned home, I soaked the retainer again in hydrogen peroxide for another 15-20 minutes before popping it in and going to bed. An hour later, I wake up not being able to shake a persistent cough so then I take out my retainer and try to go back to sleep; cough disappears and I’m able to sleep through the night. I’m afraid that I did not sterilize my retainer properly (again) and have been re-exposed to the bacteria. Will this affect treatment?