Bacterial adhesion and biofilm formation on various double-J stents in vivo and in vitro

The aim of this study was to determine whether bacterial adhesion and biofilm formation occur on various ureteric stent materials in vivo and in vitro and whether there is any correlation between biofilm formation and urinary tract infection. Using an open surgical procedure, 23 double-J stents of 8 different types were inserted in the ureters of 13 piglets. After 6 weeks intubation, 2 (9%) of the 23 stented renal units yielded positive urine culture. Scanning Electron Microscopy (SEM) showed sporadic bacteria on 7 (30%) of the 23 indwelling ureteric stents and bacterial biofilms on only 2 (9%), those indwelling the renal units which yielded positive urine cultures. Precut segments of the 8 double-J stent brands were incubated with 5 different bacterial strains. Microbiological and SEM analysis of the stents revealed that only 0.1-0.01% of the bacterial inoculum adhered to the stents. There was no statistically significant difference in bacterial adherence to the various stent materials. Interestingly, the two Escherichia coli strains with P-fimbriae adhered significantly more than the two without P-fimbriae. Sporadic bacterial adhesion to ureteric stents seemed to have little clinical significance whereas biofilm formation seemed to result in urinary tract infection. None of the tested stents proved to be superior to the others in this respect, and adhesion appeared to depend on the virulence of the bacteria rather than the properties of the biomaterials.