Nori US et al. (2006) Comparison of low-dose gentamicin with minocycline as catheter lock solutions in the prevention of catheter-related bacteremia. Am J Kidney Dis 48: 596–605

Catheter-related bacteremia (CRB) causes considerable morbidity and mortality in hemodialysis populations. A catheter-lock solution of 40 mg/ml gentamicin plus citrate effectively prevents CRB, but ototoxicity is a concern at this concentration. Nori et al. evaluated the effectiveness of gentamicin at a concentration of 4 mg/ml against control solutions of standard heparin and of 3 mg/ml minocycline, which has previously demonstrated efficacy in CRB prevention.

The 62 hemodialysis patients (53 prevalent, 9 incident) enrolled in the open-label study were evenly randomized between the gentamicin plus citrate, minocycline plus edetic acid (EDTA), and heparin groups. All patients used tunneled cuffed catheters. At 6 months, seven patients in the heparin group had developed CRB, compared with one patient in the minocycline group (P = 0.02) and no patients in the gentamicin group (P = 0.008). The observed efficacy of gentamicin led to early termination of the study. Catheter vintage had no effect on CRB rate, indicating that use of antibiotic-lock solutions need not be limited to newly inserted catheters. Four deaths occurred; none was CRB related.

The authors conclude that low-dose gentamicin effectively prevents CRB, and is preferable to minocycline on the basis of cost. The short follow-up periods of this and other studies of antibiotic catheter locks, however, do not allow conclusions to be drawn regarding potential long-term problems such as antibiotic resistance.