An in vitro bacterial touch contamination risk assessment of two CAPD twinbag systems

The objective of this study was to compare, using in vitro quantitative microbiology, the ability of two commercially available peritoneal dialysis solution delivery systems to prevent and remove, via convective fluid flow, intralumenal fluid path bacterial contamination. The two systems (A and B) differed in both the configuration of their flow control, or Y-junction and the method of fluid flow control and also in the design of their Luer tubing connectors. System A had a tubing type Y-junction that requires clamps to control fluid flow and uses a connector with a male Luer that is deeply recessed within a shroud. System B has a dial-type rigid Y-junction with in-line flow control and a connector with a male Luer that is shrouded but not recessed. System A connectors allowed significantly (p<0.0001) fewer bacteria to be transferred into the fluid path than System B after simulated touch contamination. Also, when an equivalent number of bacteria were deliberately placed into the fluid paths of both systems, System A was more effective in removal of the bacterial contamination by convective fluid flow than System B (p<0.0001), resulting in fewer organisms infused into the simulated peritoneum. Specific design features of System A, such as a recessed male Luer, and a Y-junction fluid flow path with low turbulence were likely explanations for its superior results. This study emphasizes the importance of connector and fluid path flow design in the aseptic performance of peritoneal dialysis delivery systems.