Which of the following is NOT a mechanism by which a 70% ethanol lock reduces CRBSIs?

• A. Protein denaturation
• B. Diffusion through the polysaccharide matrix of a biofilm
• C. Prevention of fibrin sheath formation
• D. Increases fibrin deposition in the catheter lumen

Answer: (D)

A 70% ethanol lock reduces CRBSIs by disrupting the biofilm and the proteins that help bacteria adhere and survive on the catheter surface. Ethanol denatures proteins, including those in bacterial cells and in the biofilm matrix, weakening and killing organisms. It also can diffuse through the biofilm’s polysaccharide matrix, allowing the ethanol to reach bacteria that are embedded within and break down the protective structure of the biofilm. Additionally, by interfering with the formation of fibrin sheaths around the catheter, ethanol reduces the scaffold that bacteria often use to adhere and persist, further lowering infection risk. Increasing fibrin deposition in the catheter lumen would actually provide more surface for bacteria, so that idea isn’t a mechanism by which the ethanol lock works.