Growth of Bacterial Biofilms on Tenckhoff Catheter Discs in vitro after Simulated Touch Contamination of the Y-Connecting Set in Continuous Ambulatory Peritoneal Dialysis

Abstract

We simulated touch contamination of peritoneal dialysis fluids perfused through an in vitro system with a modified Robbins’ device (MRD) and Y-connecting tubings, to study the pathogenesis of bacterial biofilm (BB) growth on Tenckhoff catheter (TC) discs. The spike ends of Y-connecting sets were dipped in a suspension of freshly cultured cells of Staphylococcus epidermidis (3X10⁸ cfu/ml), and connected to 2 litres of 0.5 % dianeal solution which was perfused through the MRD with plugs containing TC discs. Four simulated clinical exchanges were performed with or without prior flushing and/or bleach treatment of the Y sets. Control experiments were done with fresh Dianeal solution with no contamination, flushing, or bleach treatment. BB growth on the TC discs was examined by scanning electron microscopy (SEM) and transmission electron microscopy and quantitated by routine culture of scrapings from the discs. We noted that touch contamination of dialysis fluids via the spike ends of the connecting sets can generate dense BB growth on TC discs in this experimental system (62 ± 8% by SEM and 10.2 ± 8.3 X 10³ cfu/ml by culture). This growth of BB was significantly reduced by flushing the Y set with sterile Dianeal solution (24.3 ± 3% by SEM and 5.7 ± 3.5 X 10¹ cfu/ml by culture) and was absent by bleach treatment. We conclude that although bleach treatment of Y sets can prevent BB growth, the ‘flushing’ procedure alone can significantly reduce BB growth on TC from touch contamination of dialysate fluid.

Biofilms and Infection in Dialysis Patients

“…During studies of simulated touch contamination during PD exchanges in MRD, S. epidermidis formed biofilm easily on silastic catheter implants (43). Staphylococcal biofilm formation was reduced by “flush before fill” procedures and was completely abolished by treatment with bleach (43). These experiments confirmed that touch contamination from skin bacteria during dialysis exchanges is a common source of biofilm growth on PD catheters.…”

“…Touch contamination by skin bacteria like S. epidermidis during daily exchanges of PD fluids is a common cause of peritonitis in PD. During studies of simulated touch contamination during PD exchanges in MRD, S. epidermidis formed biofilm easily on silastic catheter implants (43). Staphylococcal biofilm formation was reduced by ''flush before fill'' procedures and was completely abolished by treatment with bleach (43).…”

“…These are research tools and are not suitable for routine use in clinical practice. We utilized our previously validated MRD technique of biofilm culture (41–43) to isolate, identify, and perform antibiotic sensitivity of biofilm bacteria directly from PD effluents collected from patients with peritonitis. As stated earlier, no removal of PD catheters is required by this diagnostic method.…”

Biofilms in Peritoneal Dialysis

“…During studies in MRD of simulated touch contamination during PD exchanges, S. epidermidis formed biofilm easily on Silastic catheter implants (11). Staphylococcal biofilm formation was reduced by flush-before-fill procedures and was completely abolished by treatment with bleach.…”

“…However, based on the validation of our in vitro modelling with the MRD technique of biofilm culture (9-11), we used MRD to isolate, identify, and perform antibiotic sensitivity tests on biofilm bacteria obtained directly from PD effluents collected from patients with peritonitis. The method requires no look at the PD catheters.…”