Can E Coli Related UTI Be Treated Without Antibiotics?

My granddaughter has just been diagnosed with an E coli related UTI. Is it possible to cure this type of infection without antibiotics? She has an undiagnosed medical condition where her body does not absorb magnesium and must take a high dosage of magnesium to keep her out of seizure territory, but the magnesium gives her diarrhea terribly and although she is 4 yrs old she is still in a diaper therefore she gets recurrent UTI's. The problem is that whenever she goes on an antibiotic it causes her magnesium to drop so she must be hospitalized to monitor her magnesium levels every 3 hrs. She has undiagnosed neurological issues as well which I wont get into detail about but just wondered about the UTI at this time.