Long-term effects of antibiotic-coated foley catheter on bacterial biofilm formations

Abstract

Purpose: A catheter-associated urinary tract infection, which frequently occurs in patients with an indwelling Foley catheter, can cause serious morbidity or mortality. Recently, antibiotic coated Foley catheters, to prevent catheter-associated urinary tract infections, have become commercially available. This study investigated the long-term effects of the use of antibiotic-coated Foley catheters on biofilm formations. Materials and methods: Silicone Foley or antibiotic-coated Foley catheters were indwelled in 72 patients with a neurogenic bladder. Each catheter was removed 1, 3, 5, 7, 14 and 28 days after insertion. The cell densities of the biofilm bacteria were evaluated by counting the number of colonies on plate cultures. The biofilm formations on the catheters were evaluated by scanning electron microscopy. The inner surface morphology of the catheter was imaged by field emission scanning electron microscopy (Philips-XL20SFEG), at 10kV, following gold sputtering for electrical conductance. Six catheters were studied in each group, and the means calculated for comparisons. Results: Thick bacterial biofilms were observed on both the antibiotic-coated and silicone Foley catheters 7 days after insertion. There were no significant differences in the cell densities of the biofilm bacteria between the two types of catheter during days 7-28 after insertion (p < 0.05). Two to three species of bacteria were isolated from the catheters in each patient; the most common species were Pseudomonas, Klebsiella, Serratia, Proteus species and Escherichia coli. Conclusions: The antibiotic-coated Foley catheters showed no preventive effects on the biofilm formations after 7 days of indwelling compared with the silicone Foley catheters. Our data suggest that the routine use of antibiotic-coated Foley catheters to prevent catheter-associated infection in patients with a neurogenic bladder is not reasonable. The emergence of resistance associated with antibiotic-coated catheters should be evaluated.