• Incidence of urinary tract infections measured with Urinalysis and Culture [ Time Frame: Change from Baseline urinary tract infections to post intervention, an average of 5 months. ]
  Assessment of symptomatic urinary tract infection
• Presence of abnormal ranges of complete cell counts measured by an 8ml blood draw. [ Time Frame: Change from Baseline blood draw values to post intervention, an average of 5 months. ]
  Assessment of complete blood count.
• Evaluate bladder storage using Urodynamics [ Time Frame: Change in Baseline bladder capacity to post intervention, an average of 5 months. ]
  Assessment of lower urinary tract function: Change in Baseline bladder capacity (mL) to post intervention
• Evaluate bladder emptying via measurements of voiding efficiency (%) via Urodynamics assessment or uroflow (if appropriate). [ Time Frame: Change in Baseline voiding efficiency to post intervention, an average of 5 months. ]
  Assessment of lower urinary tract function.
• Presence of bladder and kidney anatomical and morphological changes measured with Ultrasound. [ Time Frame: Change in Baseline ultrasound outcomes to post intervention, an average of 5 months. ]
  Assessment of upper and lower urinary tract
• Prevalence of different bladder management techniques, such as medication usage, measured by SCI data set Questionnaires. [ Time Frame: Change in Baseline bladder management to post intervention, an average of 5 months. ]
  Questionnaires to assess bladder management outcomes
• Rate of urinary tract infections measured by SCI data set Questionnaires. [ Time Frame: Change in Baseline urinary tract infections to post intervention, an average of 5 months. ]
  Questionnaires to rate of urinary tract infections. (Note there is no scale as a component of this questionnaire.)
• Presence of abnormal ranges of metabolic markers measured by an 8ml blood draw for a comprehensive metabolic panel. [ Time Frame: Change from Baseline blood draw values to post intervention, an average of 5 months. ]
  Assessment of metabolic parameters.

• Neurogenic Bladder
• Spinal Cord Injuries

• Drug: Gentamicin Sulfate
  Gentamicin will be compounded for immediate use in single-dose, disposable BD 50ml Luer-Lok tip syringes. The container closure system for the diluted gentamicin sulfate solution and saline solution will be sterile and processed with depyrogenation. The solution will be slowly infused into the bladder after drainage of urine is complete. While monitoring blood pressure, the solution will remain in the participant's bladder for a least 30 minutes (unless the participant is experiencing autonomic dysreflexia, and in that case, immediately drained) with the goal of attaining 2 hours.
  Other Name: Gentamicin only
• Other: Placebo instillation (saline alone)
  Saline will be compounded for immediate use in single-dose, disposable BD 50ml Luer-Lok tip syringes. The container closure system for the diluted gentamicin sulfate solution and saline solution will be sterile and processed with depyrogenation. The solution will be slowly infused into the bladder after drainage of urine is complete. While monitoring blood pressure, the solution will remain in the participant's bladder for a least 30 minutes (unless the participant is experiencing autonomic dysreflexia, and in that case, immediately drained) with the goal of attaining 2 hours.
  Other Name: Saline only
• Other: No instillation
  Participants will not receive an instillation of gentamicin or saline alone, but instead will continue standard of care. Participants will be assessed at the pre-, mid- and post-intervention time points.

• Experimental: Gentamicin
  Participants will be randomized into one of three groups. In this arm, participants will perform bladder instillations using a 50ml solution of gentamicin mixed with saline, 2 times per day. A formulation derived from 480 mg gentamicin sulfate diluted in 1 L normal saline will be used for instillation. Participants will be blinded during the study and will not know if they are receiving gentamicin or placebo (saline alone).
  Intervention: Drug: Gentamicin Sulfate
• Placebo Comparator: Placebo instillation (saline alone)
  Participants will be randomized into one of three groups. In this arm, participants will perform bladder instillations using a 50ml solution of saline alone. Participants will be blinded during the study and will not know if they are receiving gentamicin or placebo (saline alone).
  Intervention: Other: Placebo instillation (saline alone)
• No instillation
  Participants will be randomized into one of three groups. In this arm participants will not receive an instillation of gentamicin or saline alone, but instead will continue standard of care. Participants will be assessed at the pre-, mid- and post-intervention time points.
  Intervention: Other: No instillation

Inclusion Criteria:

• At least 18 years of age;
• Non-progressive spinal cord injury;
• Stable medical condition;
• Bladder dysfunction as a result of spinal cord injury
• History of recurrent UTIs (defined as 3 or more within the past year or 2 or more within the past 6 months).

Exclusion Criteria:

• Signs or symptoms of serious UTI that requires the use of systemic antibiotics;
• Use of any urine-acidifying agent, bladder irrigant, or systemic antibiotic within the previous 2 weeks;
• Participants colonized with gentamicin-resistant bacteria on baseline urine culture or a gentamicin allergy/sensitivity;
• Participants with known hearing loss and/or renal disease;
• Pregnant at the time of enrollment or planning to become pregnant during the time course of the study.