Five year old boy with entetococcus uti

Patient: My 5 year old son has enterococcus. it ws detected in hos urine sample. imextremely worried. he has already taken 14 days of trimethoprim but had to switch to amoxycillin as he had became resistant to this. he is due an ultrasound scan in 2 weeks time but im worried ad to what the complications of enterococcus might be and what it is. also if it causes damage and how je came across it in the first place? in the past he had rotavirus, hypotonia and recurrent chest and throat infections. i also feel he may of had this for some time as we have visited various gps for about 6 months now with no luck. he also put in a fresh sample today. thank you