Abstract
BACKGROUND: The antibiotic lock (AL) technique is used for sterilization ofthe intraluminal surface of catheters. This technique consists of filling a catheter lumen with an antibiotic solution and allowing it to dwell for a time sufficient to sterilize the device. Glycopeptide antibiotics (vancomycin and teicoplanin) are commonly used agents for this purpose. But studies evaluating the different dosages of these antibiotics, their optimum concentrations, and duration in AL treatment are lacking. OBJECTIVE: The aim of this study was to compare the efficacy of differentdoses of vancomycin/saline solution (VSS) and teicoplanin/saline solution (TSS) and to establish the optimal dosage and time needed to eliminate intraluminal methicillin-resistant Staphylococcus epidermidis colonization. METHODS: This in vitro AL study was conducted at the Department of Infectious Diseases and Clinical Microbiology, Adnan Menderes University Medical Faculty, Aydin, Turkey. Catheters were divided into 2 groups those colonized with slime-forming S epidermidis, and those colonized with non-slime-forming S epidermidis. In each group, catheters were locked with VSS or TSS at 1-, 3-, and 5-mg/mL doses. Catheters instilled with saline solution were used as the control group. After 12 hours of incubation, the catheters were drained and filled with human plasma. Instillation of human plasma or AL solution was alternated every 12 hours to simulate clinical conditions. Every other day, catheters locked with each antibiotic dose or saline were cultured to determine colony count. These procedures were maintained until the catheters were sterile. RESULTS: The baseline counts of slime-forming and non-slime-forming S epidermidisadhered to 1-cm segment catheters were 39 × 106 and 32 × 106 colony-forming units, respectively. The bacterial count was decreased significantly from baseline on the first day after the start of treatment (day 1) (P < 0.001). At the end of day 7, all catheters treated with antibiotics were sterile. The de creases in bacterial count were statistically similar in catheters treated with all doses of VSS and TSS. Also, the decrease in intraluminal colonization was statistically similar in catheters colonized with slime-forming S epidermidis and non-slime-forming S epidermidis. CONCLUSION: In this in vitro, blinded AL study, the efficacy of vancomycin and teicoplanin lock solutions were similar and sterilized the catheters in 7 days, suggesting that the 2 antibiotics might be selected for shorter durations compared with those currently recommended for AL treatment in catheter-related infections due to methicillin-resistant staphylococci.