Background Implanted medical catheter-related infections are increasing,hence a need for developing catheter polymers bonded to antimicrobials.We evaluated preventive effects of levofloxacin-impregnated catheters in catheterrelated Psuedomonas aeruginosa （strain PAO1） infection.Methods Drug release from levofloxacin-impregnated catheters was measured in vitro.Levofloxacin-impregnated catheters and polyvinyl chloride （PVC） catheters were immersed in 5 ml 50％ Luria Bertani medium containing 108 CFU/ml Pseudomonas aeruginosa then incubated for 6,12,24 or 48 hours at 37℃ when bacteria adhering to the catheters and bacteria in the growth culture medium were determined.Impregnated and PVC catheters were singly implanted subcutaneously in mice,50 μl （107CFU） of PAO1 was injected into catheters.After the first and fifth days challenge,bacterial counts on implanted catheters and in surrounding tissues were determined microbiologically.Bacterial colonization and biofilm formation on implanted catheters were assessed by scanning electron microscopy.Results Drug release from levofloxacin-impregnated catheters was rapid.Levofloxacin-impregnated catheters had significantly fewer bacteria compared to PVC in vitro.After first and fifth day of challenge,no or significantly fewer bacteria adhered to impregnated catheters or in surrounding tissues compared to PVC.Scanning electron microscopical images after first day displayed from none to significantly fewer bacteria adhering to impregnated implanted catheters,compared to bacteria and microcolonies adhering to PVC catheters.After the fifth day,no bacteria were found on impregnated catheters,compared to clusters surrounding mucus-like substance and coral-shaped biofilms with polymorphonuclear leukocyte on PVC catheters.After the first day of challenge,secretion occurred in all implanted catheters with surrounding tissues mildly hyperaemic and swollen.After the fifth day,minute secretions inside impregnated catheters and no inflammation in tissues,whereas purulent s
