Gentamicin Lock Therapy and Duration-Dependent Catheter-Related Bloodstream Infection Risk in Hemodialysis.

Introduction: Clinical guidelines recommend antimicrobial lock solutions when infection rates exceed specific thresholds, yet their ability to modify duration-dependent risk accumulation remains unexplored. This study compared catheter-related bloodstream infection (CRBSI) outcomes and duration-modifying effects between gentamicin-heparin and heparin-only lock protocols.

Methods: This retrospective dual-center cohort study (January 2020-December 2024) included 266 maintenance hemodialysis patients with tunneled catheters (gentamicin-heparin: n = 198, 52,193 catheter-days; heparin-only: n = 68, 15,443 catheter-days). Primary outcome was CRBSI incidence density. Firth logistic regression with interaction analysis explored duration-modifying effects. Safety was evaluated through antimicrobial resistance patterns and a cross-sectional hearing assessment (15 gentamicin-exposed patients vs. 15 matched controls) using the Hearing Handicap Inventory for the Elderly-Screening Version (HHIE-S).

Findings: Gentamicin-heparin lock was associated with a 67% reduction in CRBSI (0.17 vs. 0.52 per 1000 catheter-days; incidence rate ratio 0.33, 95% CI 0.13-0.86, p = 0.024). Stratified analysis revealed divergent duration-risk relationships: each 30-day increment significantly increased CRBSI risk with heparin-only (OR 1.11, p = 0.006) but not with gentamicin-heparin (OR 1.02, p = 0.547). The duration-protocol interaction approached significance (coefficient -0.089, p = 0.061), suggesting gentamicin lock may attenuate time-dependent risk accumulation. Among CRBSI isolates in the gentamicin cohort, 87.5% (7/8) demonstrated gentamicin resistance. HHIE-S scores did not differ significantly between the gentamicin and control groups (p = 0.507).

Discussion: Gentamicin-heparin lock effectively reduced CRBSI incidence. Stratified analysis suggested attenuation of duration-dependent risk, though the interaction did not reach significance (p = 0.061). Sustained clinical efficacy despite high resistance, alongside a favorable preliminary hearing safety profile, suggests its clinical utility while warranting careful stewardship and prospective study.