The best way to eliminate infection would be to avoid a chronic indwelling catheter. If the patient cannot void urine normally, you should consult someone who can teach her to catheterize her bladder on her own intermittently. This is a fairly standard well recognized procedure throughout the world and though it may sound difficult initially, but with practice, there is no reason why she will not be as comfortable as the next person.
I would prefer to avoid antibiotics in the absence of significant symptoms, especially fever
as she will always have some bacteria in her urine which need not be treated unless the patient is symptomatic and I would try to avoid getting her to a stage where only very expensive antibiotics will work