UTI Prevention

I'm sure this has been posted before but I need to know how to help my 91-year-old mother keep from getting several UTI's a year. She had one this past February and fell. She got another one this March. She says she cleans herself well and we just started D-Mannose. Is D-Mannose a good preventive supplement? What else can she take? We will be seeing a Uro/Gyn if they will take her insurance. If not, we will get her in with a general Urologist. She gets confused and foggy minded whenever she has these UTI's. She has a tendency to fall with these UTI's. She has no obvious symptoms other than confusion and falling.