Predictive value of urine cultures in evaluation of bacterial colonization of ureteral stents

Abstract

To evaluate the predictive value of urine cultures in the assessment of ureteral stent colonization and to investigate the frequency of double J stent colonization and stent associated bacteriuria. This observational study was conducted in the department of Urology, Dhaka Medical College Hospital from December 2006 to March 2009. A total of 100 patients (mean age 39.2 ± 9.9 years, range 18-60 years, 69 male and 31 female) needing internal ureteral stent placement for different sorts of urinary tract operations were included in the study. Sterile urine samples were obtained from each patient before stenting and all patients had been given short-term prophylactic antibiotic (5-12 days). On the day of stent removal midstream urine were obtained from all patients for microbiological culture. Stents removed by aseptic precaution. Proximal and distal tip segments (3-5 cm) were also sent for culture. The lowest and highest durations of stenting were 10 and 86 days respectively (median 35 days). Both bacteriuria and bacterial colonization was significantly higher as duration of stenting increases (p=0.045 and p<0.001). E. coli was the most common microorganism isolated from both urine and stent culture. However, colonization rate of stents was much higher (45%) than positive urine cultures (21%) indicating that urine culture is less sensitive to diagnose stent colonization (k-value = 0.49). The study concludes that bacterial colonization significantly increases with indwelling time of stent and sterile culture of urine does not rule out that the stent itself is colonized.