To investigate the natural history of bacterial colonization on the stent and in the urine after different periods of indwelling ureteral stent placement.

A total of 57 double-J stents from 52 patients (21 men and 31 women, mean age 52 years, range 20 to 79) were examined. In all patients, short-term (2 to 3 days) antimicrobial therapy was administered at the time of stenting. Regular urinalysis and urine culture were performed until the stent was removed. The stents were removed by aseptic manipulation, and the proximal and distal tip segments of the stents were obtained. Three culture specimens were acquired from each stent segment (inner surface washing suspension, outer surface washing suspension, and from the stent tip itself).

Bacterial colonies were found in 44% (25 of 57) of the stents. Of the multiple pathogens identified, Enterococcus species (6 of 25) was the most common, followed by Escherichia coli (5 of 25). After short-term antibiotic prophylaxis, the bacteria did not colonize within the first 2 weeks of stent placement. However, the colonization rate increased as the duration of the stent placement lengthened. Colonization of the stent was followed by colonization of the urine.

The results of our study demonstrated that bacterial colonization at the stent began 2 weeks after indwelling stent placement and that stent colonization preceded urine colonization. The rate of colonization increased with longer periods of stenting.