Comparative Evaluation of Microbial Transfer in Intermittent Catheters: An in vitro Study of Protective Features...

This study evaluated whether protective features incorporated into commercially available intermittent catheter (IC) types reduce microbial transfer contamination during catheterization.

A previously developed in vitro Contamination Touch Transfer Method (CTTM) was used to model microbial transfer during catheter handling and insertion.

Four hydrophilic intermittent catheters (ICs) from 2 brands (TSC-A, TSC-B; SC-1, SC-2) and 2 French sizes (14 Fr, 16 Fr) were evaluated in an in vitro simulated urinary tract model. The TSC-A and TSC-B incorporated a ring cap, introducer tip, and protective sleeve, whereas SC-1 and SC-2 incorporated a protective sleeve only. To assess microbial contamination under worst-case conditions, the model meatus and operator's gloved hands were inoculated with approximately 108 colony-forming units of Candida albicans, Escherichia coli, or Enterococcus faecium. Microbial recovery from catheter segments was analyzed on the log10 CFU scale using Tobit mixed-effects models to account for enumeration method-specific limits of quantification and experimental replicate effects. Sleeved catheter segments were compared with corresponding unsleeved controls, and catheter-type differences were evaluated for the first 2-inch (5 cm) catheter segment within each microorganism and French size.

Sleeved catheter segments generally showed lower transfer contamination than corresponding unsleeved controls, with 46 of 48 planned comparisons statistically significant after Holm adjustment. There were statistically significant overall catheter-type differences within all 6 Microbe x French size families. TSC catheter types incorporating a ring cap, introducer tip, and sleeve had significantly lower transfer contamination than sleeve-only SC catheter types in 21 of 24 planned cross-type comparisons. Separation was most consistent for C. albicans and E. faecium across both French sizes. For E. coli, TSC catheter types had significantly lower transfer contamination than SC catheter types at 14 Fr, but fewer pairwise comparisons were significant at 16 Fr.

These findings indicate that catheter protective features reduce microbial transfer contamination to the underlying catheter tube. Under this in vitro transfer contamination model, IC designs incorporating a ring cap, introducer tip, and protective sleeve provided more consistent reduction in transfer contamination than sleeve-only designs.