Predictive value of urinary cultures in assessment of microbial colonization of ureteral stents

Background and Purpose: Bacterial colonization of indwelling ureteral stent s may serve as a nidus for bacteriuria in operations where stents are manip ulated. The predictive value of urine cultures in the assessment of stent c olonization was examined in 65 patients with indwelling ureteral stents. Patients and Methods: Prophylactic antibiotic treatment was administered pr ior to stent insertion. All patients were ambulatory at the time of investi gation and were examined in the outpatient clinic. Urine cultures were take n prior to stent removal after 8 to 150 (mean 64) days. The stents were rem oved under aseptic conditions, and the proximal and distal ends were cut of f and placed in a culture medium for evaluation. None of the patients was t reated for urinary tract infection prior to stent removal. Results: Bacteriuria was found in 15% of the patients. In 35 patients (54%) , urine and stent cultures were sterile, In 20 patients (31%), the urine cu lture was sterile but the stent was colonized (Enterococcus 9, E, coli 5, S taphylococcus aureus 2, S, epidermidis 2, Candida 1, Citrobacter diversus 1 ), One patient had a sterile stent culture with bacteriuria, In 9 patients (13,5%), urine and stent cultures were identical (E, coli 4, Pseudomonas 4, Candida 1), The incidence of stent colonization did not correlate with ste nt dwelling time, The sensitivity of urine cultures for the detection of st ent colonization was poor, being 31% only. In a specific patient with negat ive urine culture, the probability of stent colonization was 36%, Conclusion: A sterile urine culture does not rule out the stent itself bein g colonized. Therefore, patients with indwelling ureteral stents and a ster ile urine culture may benefit from prophylactic antibiotic treatment prior to endourologic procedures. The prophylactic regimen must provide coverage for common gram-negative uropathogens as well as gram-positive bacteria, in cluding enterococci.