In Vitro Study of the Flush Effect in Two Reusable Continuous Ambulatory Peritoneal Dialysis (CAPD) Disconnect Systems

Abstract

Previously published in vitro results, confirmed by clinical studies, indicate that the use of a flush significantly reduces peritonitis in single-use and reusable continuous ambulatory peritoneal dialysis (CAPD) systems. Since reusable systems may use the flush plus inline disinfectant between exchanges, the question remains as to whether or not the flush could be used alone in all disconnect systems. Using an in vitro model, we evaluated the flush in two reusable disconnect systems that use both flush and disinfectant in vivo. In a series of twenty sets per organism per incubation (0 h and 10 h), Y sets were inoculated in the lumen with three pure cultures (103 CFU range). Ability of flush without disinfectant to clear sets of contamination was analyzed by collecting multiple samples at each step of the procedure, enriching with tryptone broth and verifying bacterial growth. When contaminated sets were not incubated, flush efficacy of the systems was consistent with previous data showing 100% removal of Staphylococcus epidermidis, but only partial elimination of Staphylococcus aureus and Pseudomonas aeruginosa. After incubation, simulating reusable systems, the flush was able to eliminate S. epidermidis less than 50% of the time. There was no significant difference in results between the two systems tested. Reusable systems allow more contact time between bacteria and plastic resulting in reduced flush efficacy suggesting that, for safest conditions, they should be used with inline disinfectants.