Effectiveness of a 30% ethanol/4% trisodium citrate locking solution in preventing biofilm formation by organisms causing haemodialysis catheter-related infections

Objectives: Antibiotic locks may be used to prevent haemodialysis catheter- related infections ( CRIs). This in vitro study tested the effectiveness of a novel 30% ethanol/ 4% trisodium citrate lock solution in preventing biofilm formation by the most common pathogens causing haemodialysis CRIs. Methods: Ten clinical isolates of Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli were tested. Bacterial suspensions of each isolate were prepared in a control solution of normal saline/ Mueller - Hinton broth ( MHB) and in a lock solution of 30% ethanol/ 4% trisodium citrate and MHB. The bacterial suspensions were placed into the wells of a Calgary Biofilm Device ( CBD) and incubated with fresh solution every 24 h for 72 h. The biofilm formation was assessed by removing the CBD pegs, placing them in normal saline and sonicating them for 5 min. The resulting solution was sampled and the colony counts were determined after 24 h of incubation. Results: All controls demonstrated biofilm growth of between 6 x 10(6) and 7.4 x 10(7) cfu/mL over 72 h. In the 30% ethanol/ 4% trisodium citrate lock solution, no biofilm growth was observed after 72 h of incubation. These results were consistent among duplicates of all isolates. Conclusions: The 30% ethanol/ 4% trisodium citrate lock solution prevented the biofilm formation of all isolates of S. aureus, S. epidermidis, P. aeruginosa and E. coli in vitro. Further studies are necessary to determine its efficacy and safety in the haemodialysis population.