Flagyl (metronidazole) is more commonly used for anaerobic bacterial infections, but also with activity against gram-. You dont have a UTI, but a genital infection. Urine does not flow near the epi, and the testies and prostate are sexual genital organs. You need to get a recheck, as bacteremia can be fatal. Quinolones like cipro have activity against both gram+/-....you need a C+S test first. Gram- E-coli are most common causes of these infections, but enterics and coag+ staph are causes of epiditimytis (commonly accompanied by prostatitis).
There are much better choices than metron, cuz it can cause pseudomembranous colitis (potentially fatal infection after anaerobic anti-B use).