Bacteriology of urinary tract infection associated with indwelling J ureteral stents.

PURPOSE: To investigate the microorganisms responsible for urinary tract infection (UTI) and stent colonization in patients with indwelling J ureteral stents and to compare the antimicrobial susceptibility pattern of the isolates from urine and J stents in order to establish the etiologic agents of bacteriuria and colonized stents in such patients and provide baseline data on an antibiotic policy for the urology unit. PATIENTS AND METHODS: Midstream urine from 250 patients requiring J stent insertion was investigated microbiologically prior to stent insertion and on the day of stent removal. After stent removal, 3 to 5 cm of the tip located in the bladder was also sent for culture. Patients' bio-data and underlying diseases were documented. Those with no known systemic diseases ("normal patients") were also studied as controls. Of the 250 patients studied, 152 (61%) were normal, while 27 (11%), 53 (21%), and 18 (7%) had diabetes mellitus (DM), chronic renal failure (CRF), and diabetic nephropathy (DN), respectively. The mean duration of stent retention was 27 days. All microbial isolates were tested for their susceptibility to a panel of 10 antibiotics. RESULTS: Twelve patients (5%) before stent insertion and 42 patients (17%; P < 0.001) on the day of stent removal had positive urine cultures. One hundred four stents (42%) were culture positive. Of the 104 patients with positive stent cultures, in 62 patients (60%), urine culture was sterile. The commonest isolates were Escherichia coli, Enterococcus spp., Staphylococcus spp., Pseudomonas, and Candida spp. On the day of stent removal, urine culture was positive in 28% of the normal patients compared with 57% (P = 0.11), 78% (P < 0.001), and 62% (P < 0.001) of patients with CRF, DM, and DN, respectively. Stent isolates were more resistant to antibiotics than the organism isolated before stent insertion. CONCLUSION: An indwelling J ureteral stent carries a significant risk of bacteriuria and stent colonization. The sensitivity of urine culture to stent colonization is low, and therefore, a negative culture does not rule out a colonized stent. Bacteria cultured from urine after stent insertion and from the stents are more resistant to antibiotics than are those cultured from urine before stent insertion. Norfloxacin or ciprofloxacin is recommended as prophylaxis prior to stent insertion, and an aminoglycoside can be added to treat symptomatic patients with severe infections.

Factors predisposing to urinary tract infection after J ureteral stent insertion.

PURPOSE: We determined the group of patients most likely to have bacterial infection or colonization of J stents inserted to relieve ureteral obstruction. MATERIALS AND METHODS: Midstream urine from 250 consecutive patients who required indwelling J stent insertion obtained before stent insertion and on the day of stent removal was analyzed by microbiological testing. At stent removal 3 to 5 cm. of the stent tip located inside the bladder was also sent for culture. Patient sex, duration of stent insertion and systemic disease, such as diabetes mellitus, chronic renal failure or diabetic nephropathy, were recorded. Patients without systemic disease were classified as normal. The rates of bacteriuria, stent colonization and symptomatic urinary tract infection were compared in patients with and without systemic disease. RESULTS: Of the 250 patients studied 180 (72%) were men and 70 (28%) were women, while 152 (60.8%) had no systemic disease, 27 (10.8%) had diabetes mellitus, 53 (21.1%) had chronic renal failure and 18 (7.2%) had diabetic nephropathy. The bacteriuria rate was 4.2% for stents removed within 30 days and 34% for stents removed after 90 days (p <0.001). Overall the bacteriuria rate in women was 24.3% compared with 13.9% in men (p <0.06). The rate of bacteriuria in normal patients was significantly lower (3.3%) than in patients with diabetes mellitus, chronic renal failure and diabetic nephropathy (33.3%, 39.6% and 44.4%, respectively, p <0.001). The colonization rate of the tip of the stent was higher in women (64.3%) than in men (34.7%). The stent was removed prematurely in 9 of the 250 patients (3.6%) because of septicemia, including 7 women (77.8%) with systemic disease. CONCLUSIONS: The risk of bacteriuria and colonization of the J stent tip is significantly enhanced by the duration of stent retention, patient sex and the systemic disease, such as diabetes mellitus, chronic renal failure and diabetic nephropathy. These categories of patients should undergo shorter stent retention, antimicrobial prophylaxis and careful followup to minimize infectious complications.