The investigators performed a 3-arm clinical trial at the "Dr. José Eleuterio González" University Hospital, a tertiary-care academic hospital in Monterrey, Mexico. The study population were patients from a charity institution for individuals with SB (Asociación de Espina Bífida de Nuevo León A.B.P.) who were treated in our hospital. Patients and parents were offered optional entrance to the study. Inclusion criteria were age ≥ 2 years, diagnosis of SB, self-IC or performed by a trained person, ≥ 3 months using a reused PVC catheter (1 per week) with a clean technique, able to read and understand the informed consent. Exclusion criteria were other causes of NB, symptomatic UTI at the time of initial evaluation (defined as a positive urine culture with pyuria, and odorous urine, flank pain, malaise, or fever), inconsistent IC, an indwelling catheter, allergy to PVC, urethral pathology (eg, stricture, false passage, hypospadias) and rejection to participate in the trial. The use of a prophylactic antibiotic was not an exclusion criterion provided that the participant continued with their usual therapy for the study duration.

The sample size was calculated considering a total of 135 active patients with SB treated in our hospital, using a power of 80%, an expected difference of 50% between arms, and an alpha level set at 0.05. The sample size needed was 75 subjects, using methods for correlated binary data and repeated measures. Subjects were assigned into 3 groups: Group 1 was assigned to use a single-use PVC catheter. Groups 2 and 3 were assigned to use the standard practice modality, a reused PVC catheter. All groups had a follow-up of 8 weeks. Subjects were assigned to block sizes of 6 using a computer-generated list. A blinding process was impossible due to the nature of the intervention.

All groups were instructed to use sterile water-soluble lubricant in each catheterization. In the reused catheter groups, after catheterization, the PVC catheter was washed with water and soap and stored in a container with 0.5% benzalkonium chloride or washed with water and soap alone. Each catheter was programmed to last a week. Patients and parents were instructed to use clean technique by hand washing with water and soap, and penis/vulva cleansing with antiseptic wipes. Researchers reinforced the IC technique before the trial. All participants provided written informed consent.

The primary outcome measure was UTIs. A positive urine culture was defined as the growth of \>100,000 CFU. Positive urine cultures were then classified as asymptomatic bacteriuria, defined as a positive urine culture with no symptoms, and UTI, defined as a positive urine culture with cloudy, odorous urine, flank pain, malaise or fever. A total of 6 urine samples were performed per participant, considering baseline the first urine culture, and follow-up the following samples. Participants at baseline were classified as asymptomatic bacteriuria or sterile sample, considering that UTI was an exclusion criterion on baseline sample. Follow-up outcome was classified as sterile (negative urine cultures in all follow-up samples), asymptomatic bacteriuria (at least 1 positive urine culture with no symptoms at any sample), and UTI (at least 1 positive urine culture with symptoms).

The secondary outcomes included person-urine sample UTI, febrile UTI, non-febrile UTI, asymptomatic bacteriuria, and antibiotic use for any reason. Demographics, pharmacologic therapy, urological background, and urodynamic characteristics were evaluated in order to establish an association with the presence of UTI. Urine cultures were programmed at days 0, 7, 14, 28, 42, and 56. Researchers collected all urine samples from a fresh midstream catheter specimen using sterile technique.

An impartial statistician analyzed the data. Categorical variables were expressed in frequencies and percentages. Numerical variables were expressed as means and standard deviation. Clinical and demographic characteristics were analyzed using the χ2 test for categorical variables, and the t-test (or Mann-Whitney test in the absence of normal distribution) for continuous variables. Statistical significance was set at p \<0.05. SPSS® software version 20.0 (IBM Corporation, Armonk, NY) was used for all analyses. No funding organization had an influence in the study design, analysis or conclusions.