Can I submit a urine sample to test for a UTI, or can a doctor prescribe with results from a home strip?

As the son-caregiver of an 84 year old female how and to who can I submit a urine sample to test for a UTI?S
Is it possible to prescribe something as a prevention and if so what would commonly be prescribed. What is the likelihood of causing other complications with side effects etc?
Her "primary care doctor has not been much help, refusing to make offic appointments due to mom's physical limitations and advised home "nurse's" were her only option, doesn't sound right to me.
I thank here and now anyone who responds with knowledge, experience or advice.
Moms advocate (and agent)
(second stroke, limited speech, incontinence, history of UTIs, and at home)