Abnormal urine drainge is a risk for urine infection. there are few things you can do -
1. Make her pass stools once daily. Kids with constipation
have abnormal bladder function which predisposes to back flow of urine and urine infection.
2. Complete longer course of antibiotics [3-4 weeks] instead of 1-2 weeks of antibiotics.
3. Antibiotic prophylaxis
for 3-6 months at bedtime after emptying bladder.