My Daughter Tested Positive On A Rapid Strep Test On

My daughter tested positive on a rapid strep test on August 25. She was prescribed Augmentin for 10 days, and a month later tested positive on a rapid strep test again. This time she was given a shot of Rocephin and prescribed Augmentin for 14 days. She went to the follow-up appointment on Day 14, and the doctor did a rapid test and cultured her throat to make sure the strep was gone. Well they called me today, and said it grew Enterobacter. Therefore, she was prescribed Bactrim for 10 days. Where does one get this type of bacteria? Is it because she has been on so many antibiotics? Should I be stressed out about this?