Abstract:ObjectiveTo compare the efficacy of antibiotic lock technique (ALT) and systemic medication on the treatment of central venous catheterrelated infection(CRI). MethodsCatheters which had been formed bacterial biofilm in vitro were implanted into the central venous of rabbits, and rabbits were randomly divided into two groups, catheter group received the injection of mixture of antibiotics and heparin， systemic group received intramuscular injection of antibiotics and intraductal injection of heparin solution. Medicine was given continuously for 10 days, catheter blood and peripheral venous blood were taken every day before replacing the medicine, bacterial colony counts were detected. All rabbits stopped using antibiotics on day 11, then removed catheters after a 5day observation of catheterization. Before extubation, the catheter blood and peripheral blood were collected to perform bacterial colony counting and antimicrobial susceptibility testing， and removed catheters were performed catheter tip bacterial culture and observation of biofilm. ResultsDuring the medication period, the average bacterial counts of catheter blood in catheter group at different time were all lower than systemic group, difference was statistically significant(all P＜0.05）；from the 4th day, the catheter group gradually appeared positive specimens of peripheral blood culture(a total of 6 cases), and systemic group appeared positive specimens on the second day(a total of 31 cases). During medicine withdrawal period, bacterial counts of catheter blood in two groups on the day of extubation were both higher than those on the day of medicine withdrawal, differences were both statistically significant(both P＜0.05). On the day of medicine withdrawl, 2 cases in catheter group and 8 cases in systemic group were isolated bacteria from peripheral blood; there was no new positive specimens in catheter group on the day of extubation, but there was 1 new positive specimen in systemic group. Catheter tip bacterial count in systemic group was higher than catheter group (［8.02±0.05］ log10CFU/mL vs ［3.12±0.14］log10CFU/mL, t=26.82，P＜0.05）. 33.33% of specimens in catheter group could be observed scattered biofilm, while all specimens of systemtic group were covered by biofilm. Bacterial culture and antimicrobial susceptibility testing of catheter blood and peripheral blood before extubation revealed that diameter of the zone of inhibition in catheter group ranged 19-20 mm, in systemic group ranged 15-16 mm, bacteria from two groups were all sensitive to commonly used antimicrobial agents. ConclusionIn the treatment of central venous CRI, the effect of ALT on local clearance of bacteria is better than that of systemic administration, and it can significantly reduce systemic infection. However, if bacterial biofilm in the catheter is not completely cleared, infection can still relapse after medicine withdrawal. Therefore, accurate dosage and medication time is worthy of further quantitative study.