Methenamine
"Went on vacation in the Dominican came back with a uti. Not the souvenir I wanted , I believe I got it from the filthy water I swam in. Haiti is on the other side and have no sewer system. If you swim with a tampon in and don't remove it right away it will stew with the the ocean water.  I struggled for a year & I ended up taking ceftin for 3 months straight in order to kill the multi drug resistant ecoli that had invaded my bladder cells. It took 3 months to shed the lining of my bladder with the invaded cells. My urologist put me on hiprex for bladder maintenance. It works! I'm a med tech and dip my urine and look at it under the scope constantly, my urine stays acidic and no ecoli would want to take up residency :)"