Gram-positive bacteria resisted CLS more than Gram-negative bacteria and fungi.
30.0% TSC showed the highest antimicrobial activity across all tested microorganisms.
30.0% and 46.7% TSC were more effective against Candida albicans than heparin.
CLS was more effective in silicone catheters than polyurethane catheters.
Antimicrobial effectiveness of TSC concentrations may be microbe dependent.
Catheter-related infections (CRIs) are a significant concern in central venous catheters (CVCs), especially in longer-term usage associated with tunneled hemodialysis catheters (TDCVCs). In this study, we evaluated the antimicrobial efficacy of different concentrations of trisodium citrate (TSC) and heparin as catheter lock solutions (CLSs) in an in vitro model.
The in vitro model mimicked the intraluminal environment of TDCVCs, considering catheter material, microbial species, and interdialytic periods. Various concentrations of TSC and 1000 units/mL heparin were tested for their antimicrobial activity against common infective agents.
In this study, we found notable variations in antimicrobial efficacy of CLSs across different microorganisms. Gram-positive bacteria (log reduction [LR] = 1.18, 95% confidence interval [CI] = 1.1–1.26) were more resistant to all tested CLSs than Gram-negative bacteria (LR = 3.42, 95% CI = 3.09–3.75). Across all microorganisms and CLSs, there was a 1.97 LR (95% CI = 1.75–2.19) in polyurethane catheters and a 2.25 LR (95% CI = 2.04–2.46) in silicone catheters. Here, 30.0% TSC (LR = 4.33, 95% CI = 3.67–4.99) and 46.7% TSC (LR = 3.85, 95% CI = 3.55–4.15) were significantly more effective against Candida albicans than heparin (LR = 1.78, 95% CI = 1.11–2.45). Also, 30.0% TSC CLSs exhibited the highest average antimicrobial activity across all tested microorganisms (LR = 2.3, 95% CI = 1.98–2.62).
Antimicrobial efficacy of CLSs is not uniform against differing microorganisms. Here, 30.0% TSC was the most effective CLS tested, and 30.0%/46.7% TSC were significantly more effective against Candida albicans than heparin. Efficacy did not uniformly increase with TSC concentration. These findings suggest further research is warranted to optimize CLS usage.