Objective The efficacy of chlorhexidine- and silver sulfadiazine-coated central venous catheters (CSS-CVC) against catheter-related infection remains controversial. We hypothesized that the loss of silver nanoparticles may reduce the antibacterial efficacy of CSS-CVCs and that this loss could be due to the frictional force between the surface of the CVC and the bloodstream. The objective of this study was to investigate whether the antimicrobial effect of CSS-CVCs decreases with increasing exposure time in a bloodstream model and quantitatively assay the antimicrobial effect of CSS-CVCs compared with polyurethane and antiseptic-impregnated CVCs. Methods Each CVC was subjected to 120 hours of saline flow and analyzed at intervals over 24 hours. The analyses included energy-dispersive X-ray spectroscopy, scanning electron microscopy, and optical density after a Staphylococcus aureus incubation test. Results The weight percentage of silver in the CSS-CVCs significantly decreased to 56.18% (44.10% ± 3.32%) with 48-hour catheterization and to 18.88% (14.82% ± 1.33%) with 120-hour catheterization compared with the initial weight percentage (78.50% ± 6.32%). In the S. aureus incubation test, the antibacterial function of CSS-CVCs was lost after 48 hours [3 (N/D) of OD]. Similar results were observed in a pilot clinical study using 18 CSS-CVCs. Conclusions We found that the efficacy of CSS-CVCs decreased over time and that the antibacterial function was lost after 48 hours of simulated wear-out. Therefore, antibiotic-impregnated CVCs may be a better option when longer (>48 hours) indwelling is needed.
Keywords: Antibacterial activity; bloodstream model; central line infections.