I am not sure that you can get access to urine analysis without getting consent from the patients. If you can pass that hurdle, then it seems to me that your best bet would be in a hospital lab, because most patients with a UTI would likely end up in the hospital's emergency department (and thus the specimen would be analyzed in the hospital's lab). Of course, there may be central labs that will be analyzing such specimens sent from physician offices, but that would be much harder to obtain.
Again, the most significant barrier is that you will have to obtain patient consent!
The first thing you need to do is to submit your research protocol to any research ethics committee closest to you. The committee must of course be recognized and approved bu the government. After obtaining and approval then you can know approach any hospital of your choice with your approval letter so that the clinical and laboratory staffs can asist you. You will then need to recruit participants into the study by explaning your study to the target subjects and seeking their consent before obtaining their samples.