Antimicrobial lock treatment using 40 mg/mL(-1) of tetrasodium EDTA for at least 21 hours could significantly reduce or potentially eradicate CVC-associated biofilms of clinically relevant microorganisms.

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This biofilm study was conducted to assess the in vitro activity of tetrasodium EDTA on catheters that had been routinely removed from hemodialysis patients at Leeds Teaching Hospitals Trust due to maturation of fistula. Catheters were screened by culture of through-catheter flush, and isolates were identified by standard methodologies; 20 isolates were found to be biofilm positive. Initial biofilm cell count levels averaged above 10 5 CFU/1-cm catheter section. Bacteria identified in the biofilms were gram-negative (1 isolate), gram-positive (11 isolates), or mixed species (8 isolates). After a 24-h lock, 40 mg of tetrasodium EDTA per ml was effective at eradicating the total biofilm viable count in almost all cases. The efficacy of tetrasodium EDTA as a catheter lock potentially shows that this agent could substantially reduce catheter-related infections and be used to treat patients with limited access.Catheters have become essential in the management of critical-care patients, yet the inside of a catheter is a major source of infection due to biofilms (1, 3). It has been found that at least 70% of all nosocomial bloodstream infections occur in patients with central venous catheters (7). Traditionally, catheters have been locked with normal saline or heparin solutions, sometimes in combination, to provide anticoagulant activity. Normal saline is generally used to lock short-term peripheral intravenous catheters, but saline has no anticoagulant or antimicrobial activity. Heparin solutions are generally used to lock vascular catheters. Heparin has anticoagulant activity, but it does not function as an antimicrobial and therefore does not provide protection from catheter-related infections. Recently, antibiotic lock solutions, with or without an anticoagulant (such as vancomycin-heparin), have been used for the prevention and management of catheter-related bacteremia (2,8,15). However, there are concerns, particularly with the use of a vancomycin flush solution, because of the potential for the development of resistant organisms (5, 9).EDTA is a calcium and iron chelator with anticoagulant activity. However, as a disodium salt it has been documented to have limited antistaphylococcal and anti-Candida activities (6,12,13). In contrast to this was a study by Raad et al., who demonstrated that minocycline and EDTA have highly synergistic activities in the decontamination of catheter surfaces when they are combined in a solution (10). It was found in that study that minocycline-EDTA was active against staphylococci, gram-negative bacilli, and Candida organisms that colonize polymers. This suggests a possible role of EDTA in catheter lock procedures.We undertook the present study by using in vivo renal lines in an in vitro technique to test the efficacy of tetrasodium EDTA on catheters removed from patients in order to determine its potential as a catheter lock solution to treat preformed biofilms and, ultimately, catheter-related infections. MATERIALS AND METHODSExperimental design. The study was conducted at the Le...

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