Evaluation of retrograde bacterial migration in a prototype urinary drainage system with a silicone oil barrier.

BACKGROUND

Retrograde contamination of urinary drainage systems is a recognised pathway contributing to catheter-associated urinary tract infection. We evaluated retrograde bacterial migration in a prototype urinary drainage system incorporating a silicone oil barrier during a 14-day in-vitro challenge.

METHODS

An automated in-vitro model (N = 7) simulated clinical conditions, including continuous flow (29 mL/h), physiological temperature (37 °C), hourly chamber emptying, daily bag emptying, and repeated 90° tilting to mimic patient transport and repositioning. Collection bags were inoculated with Proteus mirabilis CCUG 26767ᵀ. After 14 days, six predefined locations were analysed for microbiological culture and field-emission scanning electron microscopy (FE-SEM).

RESULTS

P. mirabilis was detected in all collection bags (7/7) and in one of seven bag inlets (1/7). No bacterial growth was observed in the chamber, drainage tubing, or catheter connector (0/7), indicating the absence of detectable retrograde migration to proximal components. FE-SEM confirmed biofilm formation confined to distal components, with no bacterial attachment detected proximally.

CONCLUSIONS

In this in-vitro study, no detectable retrograde migration of P. mirabilis was observed in the prototype system during a 14-day dynamic challenge. Further studies using larger sample sizes, additional uropathogens, concurrent control systems, and clinical evaluation are warranted to determine the contribution of the barrier mechanism and its potential clinical applicability.