My mom is having recurring uti's and I understand that a probiotic could be helpful in preventing these. Can you recommend a probiotic for seniors?

Probiotics are better for regularity rather then UTIs. Probiotics are meant to reintroduce and reenforce the gut bacterial. IT has precious little to do with your urinary tract, which something completely different.

I would get your doctor to look at this issue rather then searching online for a cure. If her doctor isn't getting you any satisifaction, then get a second opinion.

The first thing you have to identify is the cause of the UTI. Does she regularly catch herself? Does she wear cotton panties,mor nylon?

As was mentioned, probiotics are treated more for gastrointestinal issues rather than bladder issues.