Intervention: Participants' number of UTIs during the six-month treatment period will be compared to the number they incurred during the six months prior to treatment. Participants complete a baseline visit which consists of medical history, informed consent, urinalysis/culture indicating no active UTIs, metabolic panel, and self-reported measures about complications, symptoms, community participation and quality of life. Similar information is collected at the end of treatment. At a 3-month follow up visit, all available data is obtained through phone interviews and/or medical chart reviews except for self-report measures. Participants begin active treatment using Gentamicin plus saline solution after they have completed all requirements. Instillations of treatment solution occur nightly after the participant's last evening catheterization. Bi-weekly calls are conducted to ensure compliance, answer questions and document adverse events. Participants will stop the trial if they develop an UTI. After receiving treatment for the UTI by their physician, they will go into a washout period of a week before resuming the trial with Gentamicin instillations.