Risk factors for lower urinary tract infection and bacterial stent colonization in patients with a double J ureteral stent

Bridging the knowledge gap: past, present and future of antibiotic use for ureteral stents

OBJECTIVE

To evaluate the available literature on ureteric stent-related infections, the use of antibiotics and bacterial colonisation to identify the current incidence of stent-related infections, unveil knowledge gaps and generate potential hypotheses for future research.

METHODS

A literature review was conducted using PubMed, Cochrane and urological association websites identifying relevant English literature published between 1983 and January 2024.

RESULTS

There is a worldwide lack of guidelines for antibiotic prophylaxis for stent placement, exchange or extraction. In patients with a negative preoperative urine culture undergoing ureteroscopy and stent placement, it may be considered to only provide prophylaxis in presence of risk factors. However, in pre-stented patients a preoperative urine culture is important to guide prophylaxis during endourological surgery. During stent indwell time, antibiotic prophylaxis does not show any advantage in preventing urinary tract infections (UTIs). There is no strong evidence to support the use of antibiotics at time of stent removal. In the absence of any clear evidence, management strategies for treating UTIs in patients with ureteric stents vary widely. Stent exchange could be considered to remove the biofilm as a potential source of bacteria. Stent culture can help to guide treatment during infection as urine culture and stent culture can differ.

CONCLUSION

In terms of good antibiotic stewardship, urologists should be aware that unnecessary use of antibiotics provokes bacterial resistance. There is a great need for further research in the field of antibiotic prophylaxis and stent-related infections to develop evidence that can help shape clear guidelines for this very common urological practice.

Recent development and future application of biodegradable ureteral stents

Ureteral stenting is a common clinical procedure for the treatment of upper urinary tract disorders, including conditions such as urinary tract infections, tumors, stones, and inflammation. Maintaining normal renal function by preventing and treating ureteral obstruction is the primary goal of this procedure. However, the use of ureteral stents is associated with adverse effects, including surface crusting, bacterial adhesion, and lower urinary tract symptoms (LUTS) after implantation. Recognizing the need to reduce the complications associated with permanent ureteral stent placement, there is a growing interest among both physicians and patients in the use of biodegradable ureteral stents (BUS). The evolution of stent materials and the exploration of different stent coatings have given these devices different roles tailored to different clinical needs, including anticolithic, antibacterial, antitumor, antinociceptive, and others. This review examines recent advances in BUS within the last 5 years, providing an in-depth analysis of their characteristics and performance. In addition, we present prospective insights into the future applications of BUS in clinical settings.

Can Double J stent encrustation be predicted by risk analysis and nomogram?: A retrospective case-control study

To explore the risk factors and develop a nomogram to predict Double J stent encrustation incidence. The general demographic characteristics and underlying risk factors of 248 patients with upper urinary tract calculus who underwent endoscopic lithotripsy and Double J stenting at the Fifth Affiliated Hospital of Sun Yat-Sen University between January 1st, 2018 and January 1st, 2023 were retrospectively analyzed. Among them,173 patients were randomly selected to form the development cohort. A multivariate logistic regression model was employed to identify the independent risk factors associated with Double J stent encrustation, and a nomogram was developed for predicting its occurrence. Additionally, 75 patients were randomly selected to form the validation cohort to validate the nomogram. Multivariate logistic regression analysis revealed that several factors were significantly associated with Double J stent encrustation: indwelling time (odds ratio [OR]1.051; 95% confidence interval [CI] 1.030-1.073, P < .001), urine PH (OR 2.198; 95% CI 1.061-4.539, P = .033), fasting blood glucose (OR 1.590; 95% CI 1.300-1.943, P < .001), and total cholesterol (OR 2.676; 95% CI 1.551-4618, P < .001).Based on these findings, A nomogram was developed to predict the occurrence of Double J stent encrustation. The nomogram demonstrated good performance with an area under the curve of 0.870 and 0.862 in the development and validation cohorts, respectively. Furthermore, the calibration curve indicated a well-fitted model. We constructed and validated an accessible nomogram to assist urologists in evaluating the risk factors associated with Double J stent encrustation and predicting its likelihood.

Factors influencing bacterial colonization of double J ureteral stents: a prospective study

Background

To investigate the microorganisms responsible for double J stent (DJS) colonization, bacteriuria, and the drug susceptibility of the isolates. We also tried to determine factors associated with stent colonization, such as indwelling time, sex, age, and comorbidities.

Materials and methods

This study is a prospective analysis of patients following DJS ablation. A total of 155 patients from our institution were enrolled in this study between January 2023 and May 2023. Bladder urine was collected in a sterile container prior to stent removal for bacteriological exam. The removed stents were divided into three parts: top (Renal), middle (Ureteral), and bottom (Bladder); 3 cm pieces from each part were taken and placed in a sterile test tube for bacteriological investigation.

Results

The mean age of patients with positive stent culture was 61.17±12.82 versus 55.94±10.32 when stent culture is negative, which is statistically significant P=0.016. Diabetes and bacteriuria are both correlated with DJS contamination with P<0.001 in the two cases. The mean duration of the use of DJS in patients with colonized stent culture is 6.45±2.98 months versus 4.06±2.20 months for the other patients; the difference is statistically significant P<0.001. The most commonly isolated pathogens on stents were Gram-negative bacilli (53.2%), dominated by Enterobacteriaceae in 19 cases (55.2%).

Conclusion

Indwelling time is the only unanimous factor of stent colonization in literature, so we recommend using DJS only if necessary and to remove it as soon as possible.

Comparing the effect of peri-operative antibiotic prophylaxis only with continuous low-dose antibiotic treatment on the incidence of urinary tract infection and stent related-symptoms in patients undergoing Double-J (DJ) stent insertion following transurethral lithotripsy (TUL)

PURPOSE

There are some controversial data about the peri operative use of antibiotics after double-J (DJ) insertion. This study aimed to compare the rates of urinary tract infections (UTI) and stent-related symptoms (SRSs) in patients who received only perioperative antibiotic prophylaxis and those given continuous low-dose antibiotic therapy for the entire stent-indwelling time following transurethral lithotripsy (TUL).

METHODS

In this randomized clinical trial 178 patients received intravenous antibiotic prophylaxis (ciprofloxacin 400 mg) before the TUL and then randomly divided into two groups to either receive no antibiotic treatment after procedure (group A, 90 patients) or to additionally receive a continuous low-dose antibiotic treatment with one ciprofloxacin 500 mg every 12 h for 3 days and then ciprofloxacin 250 mg once daily for the entire stent-indwelling time (group B, 88 patients). The rates of UTIs, SRSs and incidence of drug side-effects were evaluated in groups.

RESULTS

A total of 7 patients had positive urine culture [group A: 4 (4.4%) vs. group B: 3 (3.4%); P = 0.722]. Only 1 patient in group B had febrile UTI in the mean duration of indwelling stent in situ. The rate of SRSs was 92.2% and 89.8% in Group A and B, respectively, with no significant difference (P = 0.609). A total of 4 patients in Group B complained of gastrointestinal side effects of ciprofloxacin.

CONCLUSION

Continuous low-dose antibiotic treatment has no role in reducing the incidence of UTIs and SRSs during the indwelling time of ureteral stents compared with the peri-operative antibiotic prophylaxis only.

Analysis of Pathogens of Urinary Tract Infections Associated with Indwelling Double-J Stents and Their Susceptibility to Globularia alypum

Ureteral double-J stents are frequently used to prevent urinary obstruction. They can develop bacterial colonization and encrustation, which leads to persistent infections that seldom respond to antibiotic treatment. Thus, the goal of this study was to evaluate the local spectrum of bacterial pathogens and their susceptibility to natural compounds. A total of 59 double-J ureteral stents from 59 consecutive patients were examined. The samples were inoculated on agar culture mediums. Extracts of Globularia alypum L. were evaluated for their antibacterial activity with the diffusion and broth dilution methods; for antibiofilm activity, the crystal violet assay was used. The identification and the quantification of the different constituents of extracts were determined by reverse-phase high-performance liquid chromatography (RP-HPLC). Bacterial growth was found in three patients (5.1%). Enterococcus faecalis (1.7%), Acinetobacter baumanii (1.7%), and Pseudomonas putida (1.7%) strains were more commonly detected. They were resistant to several common antibiotics. All extracts presented several components, mainly nepetin-7-glucoside and trans-ferulic-acid, and they had antibacterial activity (MIC = 6.25 mg/mL and MBC = 6.25 mg/mL), and antibiofilm (59.70% at 25 mg/mL) properties, especially against Acinetobacter baumanii. The results achieved confirm the important role of this plant as a source of therapeutic activities.

Epidemiology and risk factors for febrile ureteral stent-associated urinary tract infections: A prospective observational cohort study

OBJECTIVES

We aimed to determine the incidence and risk factors of febrile ureteral stent-associated urinary tract infections (FUSAUTI).

METHODS

Hospitalized adult patients with ureteral stent (US) placement or exchange were prospectively enrolled. Patients with kidney transplantation of less than one year were excluded. Patients were followed until US removal/exchange or six months after inclusion.

RESULTS

Out of 663 patients included in the study, 48 had at least one FUSAUTI (cumulative incidence 7.24%; 95% confidence interval [CI] 5.39-9.48). The incidence rate of FUSAUTI was 9.04 (95% CI 6.67-12.2) per 10,000 US-days. Ten patients (20.8%) experienced sepsis or septic shock. The most frequently isolated microorganisms were Escherichia coli (38%), Enterococcus spp. (14.5%), Candida spp. (9%) and Pseudomonas aeruginosa (9%). In multivariable logistic regression analysis, female gender, an age adjusted Charlson comorbidity index score> 3, an urethral stent placement concomitant with US placement, and a history of urinary tract infection within three months were significantly associated with a higher risk of FUSAUTI.

CONCLUSION

After US placement, 7.24% of patients developed at least one FUSAUTI and, in a quarter of cases, a serious infection. Urethral stent placement was the only modifiable risk factor identified. Future interventional studies are needed to reduce FUSAUTI in these patients.

Use of Digital Healthcare Communication to Improve Urologists' Surveillance of Lithiasis Patients Treated with Internal Urinary Drainage Pre- and Post-COVID-19 Period

The COVID-19 pandemic has greatly affected lithiasis patients, which has led to an increase in the number of internal stents that have been installed. In this paper, two studies were carried out, a clinical study and a quantitative study. The aim of the first study was to evaluate the incidence and the prevalence of bacterial urinary colonization in patients with obstructive urolithiasis who needed internal stents implanted. In the second study, a multiple linear regression was created to identify the opinion of urologists regarding the importance of using digital technologies to improve the communication process. The result of the clinical study illustrates that the prevalence of urinary colonization in patients with internal stents carried out for obstructive urolithiasis was 35%, with this value being influenced by co-infection with COVID-19. The results of the quantitative study illustrated the fact that urologists are open to using new online technologies to facilitate communication with patients. The results have high importance for both doctors and patients, illustrating the main factors that have the ability to influence the communication process. The hospital managers should take into account the results obtained in this study when they choose to use certain online communication technologies with patients.

The Current State of Knowledge Regarding the Use of Double J Catheters in Treating Obstructive Urolithiasis

"Urinary lithiasis is a common pathology in the modern era. Its significance lies in the possible complications that may arise as well as in its potential for recurrence. The treatment and prevention of recurrences of urinary lithiasis often require the intervention of several specialists: urologists, nephrologists, endocrinologists, nutritionists, biochemists, etc. In the last 20 years, the treatment strategy for urinary lithiasis has changed, with minimally invasive methods replacing laparoscopic or open surgery. These are effective and have rare complications. Whichever treatment method is chosen, it may be necessary to temporarily divert the upper urinary tract by inserting double J catheters for preventive, curative, or palliative purposes. Ureteral catheters have had to be improved over time to avoid two major incidents: their migration and colonization. Various materials were used, varying the shape, size, length, guide as well as approaches. The urinary infection-urolithiasis association is frequent, without always being able to specify the cause-effect relationship. The rate of urinary colonization appears to be influenced by the presence of stent colonization as well as the time since the implant. The association of chronic diseases or emergency insertion is associated with an increased risk of urinary colonization. Complications induced by the time of the double J catheter being implanted are rare, and minor and disappear with its removal. In the case of failure to insert a double J ureteral catheter, the alternative would be to perform an ultrasound-guided percutaneous nephrostomy. Double J ureteral catheter insertion is an effective minimally invasive option in the treatment of obstructive urolithiasis. "

Does bacterial colonization influence ureteral stent-associated morbidity? A prospective study

Objective

to evaluate the effect of bacterial colonization on ureteral stent-associated morbidity.

Methods

This was a prospective study that took place between February 2019 and March 2022. We examined one hundred fifteen patients for ureteric stents application. On the same day of stent removal, the Arabic version of Ureteral Stent Symptoms Questionnaire (USSQ) was used to assess stent-associated morbidity. The stent-associated morbidity and the specificity and sensitivity of culture in the stent and midstream urine were recorded.

Results

In 15.6% of the patients stent colonization was positive; E. coli was the most common isolated organism. There was no statistically significant difference between sex, age, irrigation fluid volume and duration of operation for stent colonization. However, stent indwelling time was significantly higher in patients with stents with positive cultures. In the colonized stents, there was a statistically significant difference with regards to the total score of USSQ, pain, urinary symptoms, work performance and additional problems of USSQ. Meanwhile, there was no statistically significant difference in the general health and sexual matter.

Conclusions

stent colonization may be a contributing factor in stent-related morbidity. Stent bacterial colonization increases with the time of stent retention. Stent cultures are not needed as the same microorganisms are detected in urine cultures.

Pyeloplasty with ureteral stent placement in children: Do prophylactic antibiotics serve a purpose?

OBJECTIVES

Ureteral stents are commonly used during pyeloplasty to ensure drainage and anastomotic healing. Antibiotic prophylaxis is often used due to concerns for urinary tract infection (UTI). Although many surgeons prescribe prophylactic antibiotics following pyeloplasty, practices vary widely due to lack of clear evidence-based guidelines. We hypothesize that the rate of stent UTI does not significantly vary between children who receive antibiotics and those who do not.

METHODS

We reviewed the medical records of 741 patients undergoing pyeloplasty between January 2010 and July 2018 across seven institutions. Exclusion criteria were: age older than 22 years, no stent placed, externalized stents used, and incomplete records. Surgical approach, age, antibiotic use, stent duration, Foley duration, and urine culture results were recorded. Patients were categorized into two groups, those younger than four years of age and those four years and older as proxy for likely diaper use. Univariate logistic regression was conducted to identify variables associated with UTI. Multivariable backward stepwise logistic regression was used to identify the best model with Akaike information criterion as model selection criteria. The selected model was used to calculate odds ratios and 95% confidence intervals summarizing the association between prophylactic antibiotics and stent UTI while controlling for age, gender, and intra-operative urine cultures.

RESULTS

672 patients were included; 338 received antibiotic prophylaxis and 334 did not. These groups differed in mean age (3.91 vs. 6.91 years, P < .001), mean stent duration (38.5 vs. 35.32 days, P < .001), and surgical approach (53.25% vs. 32.04% open vs. laparoscopic, P < .001). The incidence of stent UTI was low overall (7.59%) and similar in both groups: 31/338 (9.17%) in the prophylaxis group and 20/334 (5.99%) in the non-prophylaxis group (P = .119). Although female gender, likely diaper use, and positive intra-operative urine culture were each associated with significantly higher odds of stent UTI, prophylactic antibiotic use was not associated with significant reduction in stent UTI in any of these groups. Surgical approach, stent duration, and Foley duration were not associated with stent UTI.

CONCLUSION

Incidence of stent UTI is low overall following pyeloplasty. Prophylactic antibiotics are not associated with lower rates of stent UTI following pyeloplasty even after controlling for risk factors of female gender, likely diaper use, and positive intra-operative urine culture. Routine administration of prophylactic antibiotics after pyeloplasty does not appear to be beneficial, and may be best reserved for those with multiple risk factors for UTI.

Bacterial Colonization Incidence before and after Indwelling Double-J Ureteral Stents

The upper urinary tract stenting allows to restore the ureteral patency in various situations. However, one of the main disadvantages of stenting is bacterial contamination, which can be a source of persistent infections that hardly respond to antibiotic therapy. The aim of this study was to investigate the local spectrum of bacterial pathogens and their susceptibility to antibiotics in order to optimize antibacterial therapy after upper urinary tract stenting. A prospective observational study was conducted in which 140 urine samples were examined (70 before stenting and 70 after stenting). Bacterial growth was detected in 37 patients (52.8%) before stenting and in 43 patients (61.4%) after stenting. E. coli (13 (28.8%)) and Streptococcus spp. (8 (17.6%)) strains were more commonly detected before stenting; P. aeruginosa (15 (31.2%)) and E. coli (8 (16.6%)) were usually revealed after stenting. The proportion of P. aeruginosa strains after stenting grew from 4.4% up to 31.2%. E. coli strains were resistant to ampicillin (92.3% before and 100% after stenting). Three strains of E. coli (23.1%) and six strains of P. aeruginosa (40%) were multidrug-resistant. Determination of the bacterial sensitivity to antibiotics and identification of antibiotic-resistant forms of bacteria is a factor in reducing the risk of complications and optimizing antibiotic therapy during the upper urinary tract stenting.

Characteristics of Bacterial Colonization and Urinary Tract Infection after Indwelling of Double-J ureteral Stent and Percutaneous Nephrostomy Tube

Introduction:

Infections associated with catheter in the upper urinary tract (CUUT), which include the double-J stent and the percutaneous nephrostomy (PCN) tube, get particularly infected in patients with specific risk factors for developing an infection.

Methods:

A retrospective observational study was carried out by compiling data from the hospital information system of a tertiary care center from 2019 to 2021 to evaluate infections in patients with catheter in the upper urinary tract.

Result:

A total of 200 pus samples of double-J stent (96 pus samples) and PCN tube (104 pus samples) were included in our study. Among patients with nephrostomy tube, the most frequently isolated microorganisms were Escherichia coli, followed by Pseudomonas spp. In those with a double-J stent, Pseudomonas aeruginosa, followed by E. coli were the most commonly isolated microorganisms. We found 55.72% of cases of Enterobacteriaceae-producing carbapenemases in patients with a percutaneous catheter. 66.07% of Enterobacteriaceae in patients with double-J and nephrostomy stents are extended-spectrum beta-lactamase-producing bacteria. The percentage of cultures with multiple-drug resistance (MDR) microorganisms was 38.54% in patients with double-J stents and 37.75% in nephrostomy tubes. The presence of prior urinary tract infection (P = 0.010), presence of urinary catheter before admission (P = 0.005), increased time with single urinary catheter in-situ (P < 0.001), and increased length of hospital stay (P = 0.036) were risk factors for isolation of MDR microorganisms.

Conclusion:

Pseudomonas spp. and Pseudomonas aeruginosa are commonly infecting both the CUUT. E. coli infections are more commonly infecting the nephrostomy tubes. MDR microorganisms are frequent, mainly in patients with prior urinary tract infection, presence of urinary catheter before admission, and prolonged use of a single catheter.

Healthcare-associated urinary tract infections in urology

The purpose of the present review is to report the incidence and characteristics of healthcare-associated urinary tract infections (HAUTIs) in urology with their microbiological and resistance patterns. Urinary tract infections are the main type of healthcare-associated infection in patients hospitalized in a urology ward. Patients admitted to urology departments report a high prevalence of urinary tract catheterization, up to 75% during the hospitalization period, and up to 20% had a urinary catheter before admission. An endourological surgical procedure is another risk factor for HAUTIs. Other risk factors for HAUTIs are the presence of immunosuppression and previous urinary tract infections.

In urological patients, Enterobacterales are the principal causative agent of HAUTIs, and E. coli is the most frequently isolated microorganism. However, there is also a high rate of microorganisms other than E. coli such as Klebsiella spp. and Enterococcus spp. Non-E. coli microorganisms show a higher prevalence in immunosuppressed patients and those with urinary catheters before admission. High resistance patterns are reported in patients with HAUTIs, and ESBL-producing bacteria are frequently described. Moreover, the isolation of multidrug-resistant microorganisms is more common in immunosuppressed patients, those with previous urinary tract infections, and urinary catheters into the upper urinary tract. Treatment must be tailored according to patient characteristics and patient profiles, bearing in mind the ORENUC classification for risk factors (no risk factors (O), recurrent urinary tract infections risk factors (R), extraurogenital risk factors (E), nephropathic disease (N), urological risk factors (U), permanent urinary catheter and non-resolvable urological risk factors (C)).

In vivo urinary compatibility of Mg-Sr-Ag alloy in swine model

A biodegradable metallic ureteral stent with suitable mechanical properties and antibacterial activity remains a challenge. Here we reveal the scientific significance of a biodegradable Mg-Sr-Ag alloy with a favorable combination of balanced mechanical properties, adjustable indwelling time in urinary tract and evident antibacterial activity via in vivo experiments in a swine model. Attributed to the rheo-solidification process, equiaxial microstructure and significantly refined grains (average grain size: 27.1 μm) were achieved. Mg₁₇Sr₂ and Mg₄Ag were found as the primary precipitates in the matrix, due to which the alloy obtained ca. 111% increase in ultimate tensile strength in comparison to pure magnesium. Both the in vitro and in vivo results demonstrated the satisfactory biocompatibility of the alloy. Histological evaluation and bioindicators analysis suggested that there was no tissue damage, inflammation and lesions in the urinary system caused by the degradation process. The stent also improved the post-operative bladder functions viewed from the urodynamic results. Our findings highlight the potential of this alloy as antibacterial biodegradable urinary implant material.

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Innovative biodegradable antibacterial Mg-Sr-Ag alloy.

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In vivo study in pig ureter models.

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Enhanced mechanical properties and adjustable indwelling time.

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Outstanding urinary compatibility and evident antibacterial activity.

Risk factors in bacterial colonization of internal ureteral stent

A ureteral stent is most broadly used to manage upper urinary tract disorders such as obstruction and prevent post-endoscopic complications. However, the stent may become a niche for bacterial colonization. This study aimed to determine the rate of bacterial colonization and type of bacteria in internal ureteral stents and the risk factors associated with bacterial colonization. This prospective cross-sectional study included 100 consecutive adult patients who had temporary ureteral stenting as preparation for a secondary ureterorenoscopy at Al-Yarmook Hospital/ Baghdad. All included patients were negative for bacterial culture before stenting. Stent and urine culture were performed at the time of stent removal. The colonization rate and bacteriuria in patients with internal ureteral stent were 19% and 9%, respectively. The most common bacteria in-stent and urine were E. coli accounting for 31.58% and 33.33%. Pseudomonas aeruginosa was common in stent culture, representing 21.05%. Positive bacterial culture was confirmed in 19 stents and 9 urine samples. All cases with positive urine samples were also positive for culture. Thus, the sensitivity and specificity of urine culture for detection of stent colonization were 47.37% and 100%, respectively. Diabetes mellitus, chronic renal failure, and prolonged stenting were significantly associated with increased stent colonization. The ureteral stent could be a source of urinary tract infection. The most pathogenic bacteria associated with the ureter stent are E. coli and Pseudomonas aeruginosa. Risk factors associated with stent colonization are diabetes mellitus, chronic renal failure, and prolonged indwelling time.

Urine versus stent cultures and clinical UTIs

PURPOSE

Current American Urological Association guidelines recommend pre-operative antimicrobial therapy based on prior urine cultures (UC); however, the role of stent culture (SC) in urologic practice is unclear. We examined whether UC and SC differed at the time of stent removal, as well as the association, microbiology, and timing of subsequent UTIs as related to SC.

METHODS

This was a retrospective review of 159 patients with ureteral stents for indications of urolithiasis, benign stricture, malignant obstruction, and kidney transplant. UC and SC were analyzed at the time of stent removal. Patients were followed for 12 months after stent removal for development, concordance, and timing of clinical UTIs.

RESULTS

In 159 patients, 15% had positive UC and 45% had positive SC. Of patients who had positive SC, 66% had negative UC. All patients with positive UC had identical micro-organisms on SC; however, 33% of these had SC with additional micro-organisms. Relative to those with both negative UC and SC, patients with negative UC and positive SC had a 5.7 odds, and those with both positive UC and SC had a 13.6 odds of developing a clinical UTI within 12 months. Concordance of SC and future UTI was highest in those with post-operative sepsis, and those with Candida species on SC.

CONCLUSIONS

SC was a unique risk factor for development of UTI within 12 months of stent removal. Clinicians should consider SC results when empirically treating those with post-operative sepsis or those with UTI after Candida on SC.

Recommendations of the AFU Infectious Diseases Committee on the prevention, diagnosis and treatment of infections of endo-ureteral equipment

INTRODUCTION

No recent national guidelines exist regarding the management of urinary tract infections (UTIs) in the presence of ureteral stent. This situation could lead to discrepancies in clinical management and less opportunity for a favorable patient's outcome.

METHODS

All available data published on Medline® between 1998 and 2018 were systematically searched and reviewed. All papers assessing adult patients carrying ureteral stent were included for analysis. After studies critical analysis, national guidelines for clinical management were elaborated in order to answer clinical questions.

RESULTS

A total of 451 articles were identified, of which 58 have been included. The prevalence of urinary tract infections in the presence of ureteral stent remains unknown. After 3 months, all endo-ureteral devices were colonized on microbiological study. These patients also presented a positive urine culture in 25 to 70% of the cases, often polymicrobial. Staphylococci, E. coli, Klebsiella, Pseudomonas, Enterococcus and Candida were the commonest micro-organisms responsible for urinary colonization or infection. The risk of UTI on endo-ureteral devices seemed higher the longer it stayed implanted. There is no justification in the literature to recommend a systematic change of endo-ureteral devices following a urinary tract infection.

DISCUSSION

The existing literature is rich but of poor methodological quality, and therefore does not allow to draw robust conclusions. The greatest difficulty faced in this work was to accurately differentiate urinary colonizations from true infections, including clinical symptoms and not only microbiological results.

CONCLUSION

These guidelines propose a standardized management of such common clinical situations. Well-designed studies are needed to upgrade the level of evidence of these guidelines.

Epidemiology and risk factors for ureteral stent-associated urinary tract infections in non-transplanted renal patients: a systematic review of the literature

PURPOSE

Pathophysiology and risk factors for Ureteral Stent-Associated Urinary Tract Infection (USAUTI) have been poorly investigated. This situation results in highly diverse practices regarding USAUTI prevention, diagnosis and treatment. The aim of the present study was to describe the epidemiology and risk factors for USAUTI in non-transplanted patients.

METHODS

We conducted a systematic literature review based on a comprehensive PubMed® bibliographic strategy, between October 1998 and March 2020. The methodological quality of the studies included was analyzed according to dedicated grids. The main endpoints were the correlation between different potential risk factors and infection ureteral stent-associated urinary tract infection or colonization rate. Conclusions and their level of evidence were reported on the basis of a critical analysis of the best available scientific evidence. This work has been submitted to a national review, which enabled the potentially divergent opinions of experts to be collected, thereby ensuring adequate quality of data.

RESULTS AND CONCLUSION

Twenty-six studies out of the 505 articles identified, were included in the final analysis. Staphylococcus spp, E. coli, Klebsiella spp, Pseudomona aeruginosa, Enterococcus spp. and Candida spp. were the microorganisms most often responsible for asymptomatic bacteriuria (ABU) or USAUTI. Longer indwelling time, diabetes mellitus, female gender, chronic renal failure, diabetic nephropathy and cancer were identified as risk factors for ABU and ureteral stent colonization. No specific risk factor for UTI was identified in the literature studied. A causal relationship between ureteral stent colonization and USAUTI or urosepsis remains to be demonstrated.

Comparative assessment of biodegradable-antireflux heparine coated ureteral stent: animal model study

BACKGROUND

Double J ureteral stents are widely used on urological patients to provide drainage of the upper urinary tract. Unfourtunately, ureteral stents are not free from complications, as bacterial colonization and require a second procedure for removal. The purpose of the current comparative experimental study is to evaluate a new heparin-coated biodegradable antireflux ureteral stent (BraidStent®-H) to prevent urinary bacterial colonization.

METHODS

A total of 24 female pigs were underwent determination of bacteriuria and nephrosonographic, endoscopic and contrast fluoroscopy assessment of the urinary tract. Afterward, were randomly assigned animals to Group-I, in which a 5Fr double-pigtail ureteral stent was placed for 6 weeks, or Group-II, in which a BraidStent®-H was placed. Follow-up assessments were performed at 1, 3, 6, 8, 12 weeks. The final follow-up includes the above methods and an exhaustive pathological study of the urinary tract was accomplished after 20 weeks.

RESULTS

Bacteriuria findings in the first 48 h were significant between groups at 6 h and 12 h. Asymptomatic bacteriuria does not reach 100% of the animals in Group-II until 48 h versus Group-I where it appears at 6 h. The weekly bacteriuria mean rate was 27.7% and 44.4% in Group I and II respectively, without statistical significance. In Group II there were no animals with vesicoureteral reflux, with statistical significance at 3 and 6 weeks with Group-I. The 91.2% of stents in Group-II were degraded between 3 and 6 weeks, without obstructive fragments. Distal ureteral peristalsis was maintained in 66.6-75% in Group-II at 1-6 weeks.

CONCLUSIONS

The heparin coating of BraidStent® allows an early decrease of bacterial colonization, but its effectiveness is low at the long term. Heparin coating did not affect scheduled degradation rate or size of stents fragments. BraidStent®-H avoids the side effects associated with current ureteral stents, thus should cause less discomfort to patients.

A comparison between short- and long-term D-J stent in Anderson-Hynes pyeloplasty for pelvi-ureteric junction obstruction

PURPOSE

A double-J (D-J) stent is usually kept in situ during Anderson-Hynes (A-H) pyeloplasty for pelvi-ureteric junction (PUJ) obstruction. The aim of the study is to determine whether early removal of D-J stent is better than long-term stenting.

METHODS

In this prospective comparative study, conducted from January 2018 to April 2019 in Chittagong Medical College Hospital, patients with PUJ obstruction, age less than 12 years, were divided into group A (long-term stenting) and group B (short-term stenting) by simple randomization. Main outcome variables were urinary tract infection (UTI), stent colonization, encrustation, renal cortical thickness, differential renal function (DRF), glomerular filtration rate (GFR), and flow rate in DTPA renogram.

RESULTS

There were 31 patients in each group. Median age was 5 years (IQR: 2.3 to 7 years) and male to female ratio was 2.1:1. Frequency of post-operative UTI and stent colonization were significantly higher in group A than group B (p < 0.001). All the patients of both groups had similar improvement in renal cortical thickness, DRF, GFR, and flow rate. The study was potentially limited by its small sample size and high median age (5 years).

CONCLUSION

Early removal of D-J stent had lower incidence of UTI, stent colonization, encrustation, and stent migration.

Clinical significance of DJ stent culture in patients with indwelling ureteral stents prior to endourological intervention

BACKGROUND

Ureteral stents are placed to relieve ureteral obstruction in various endourological surgery. As soon as it is inserted it is rapidly colonized by host of microorganism. Culture and sensitivity pattern of these growing microorganism on the stent may provide us an insight to treat postoperative urosepsis in high risk patients with indwelling DJ stents.

MATERIALS AND METHODS

Prospective study between September 2018 and August 2019 with enrollment of 100 patients to determine the ability of urine culture (UC) to predict stent culture (SC) status, to identify associated infectious pathogens with their antibiotic sensitivity patterns and to evaluate the association between SC and post-endourological intervention sepsis.

RESULTS

Colonization of bacteria on stent culture (SC) was identified in 53 out of 100 patients (53%). Most of the organism grown on SC were multidrug resistant and they were resistant to most commonly prescribed antibiotics like fluroquinolones, cephalosporins, and aminoglycosides .These organisms were only sensitive to newer antibiotics. Indwelling time of ureteral stent was directly proportional with SC positivity (p < 0.05). Association of Urine culture at DJ Removal and DJ stent culture was not statistically significant.

CONCLUSION

Very low rates of colonization within 6 weeks after the insertion of stents. Sterile culture of urine does not rule out colonization of the stent. Most of the urinary pathogens as well as the organisms grown on DJ stent are resistant to fluroquinolones and cephalosporins.

Ureteral Stent Microbiota Is Associated with Patient Comorbidities but Not Antibiotic Exposure

Ureteral stents are commonly used to prevent urinary obstruction but can become colonized by bacteria and encrusted, leading to clinical complications. Despite recent discovery and characterization of the healthy urinary microbiota, stent-associated bacteria and their impact on encrustation are largely underexplored. We profile the microbiota of patients with typical short-term stents, as well as over 30 atypical cases (all with paired mid-stream urine) from 241 patients. Indwelling time, age, and various patient comorbidities correlate with alterations to the stent microbiota composition, whereas antibiotic exposure, urinary tract infection (UTI), and stent placement method do not. The stent microbiota most likely originates from adhesion of resident urinary microbes but subsequently diverges to a distinct, reproducible population, thereby negating the urine as a biomarker for stent encrustation or microbiota. Urological practice should reconsider standalone prophylactic antibiotics in favor of tailored therapies based on patient comorbidities in efforts to minimize bacterial burden, encrustation, and complications of ureteral stents.

A prospective randomized study to define the role of low dose continuous prophylactic antibiotics and anti-adherence agents in altering the microbial colonization related to indwelling double-J stents

Objective

Despite conflicting evidence, it is common practice to use continuous antibiotic prophylaxis (CAP) in patients with indwelling double-J (DJ) stents. Cranberry extracts and d-mannose have been shown to prevent colonization of the urinary tract. We evaluated their role in this setting.

Methods

We conducted a prospective randomized study to evaluate patients with indwelling DJ stents following urological procedures. They were randomized into three groups. Group A (n=46) received CAP (nitrofurantoin 100 mg once daily [OD]). Group B (n=48) received cranberry extract 300 mg and d-mannose 600 mg twice daily (BD). Group C (n=40) received no prophylaxis. The stents were removed between 15 days and 45 days after surgery. Three groups were compared in terms of colonization of stent and urine, stent related symptoms and febrile urinary tract infections (UTIs) during the period of indwelling stent and until 1 week after removal.

Results

In Group A, 9 (19.5%) patients had significant bacterial growth on the stents. This was 8 (16.7%) in the Group B and 5 (12.5%) in Group C (p-value: 0.743). However, the culture positivity rate of urine specimens showed a significant difference (p-value: 0.023) with Group B showing least colonization of urine compared to groups A and C. There was no statistically significant difference in the frequency of stent related symptoms (p-value: 0.242) or febrile UTIs (p-value: 0.399) among the groups.

Conclusion

Prophylactic agents have no role in altering bacterial growth on temporary indwelling DJ stent, stent related symptoms or febrile UTIs. Cranberry extract may reduce the colonization of urinary tract, but its clinical significance needs further evaluation.

Role of cultural analysis in patients with indwelling ureteral stent submitted to ureteroscopy for stones

BACKGROUND

Aim of our study is to analyze the incidence of postoperative infectious complications and to assess its predictors in patients with indwelling ureteral stent treated with ureteroscopy (URS).

METHODS

We retrospectively evaluated data of patients treated with URS from January 2017 to July 2018 at our center. We included 88 consecutive patients with available stent culture (SC) and urine culture (UC). Cefoxitin 2 g IV was given as prophylaxis in all patients with negative preoperative UC; otherwise, the choice of antibiotic was based on antibiogram. Ureteral stent was removed before URS procedure and analyzed. No postoperative antibiotic was given. Multivariable logistic regression analysis was built to assess preoperative predictors of postoperative infectious complications.

RESULTS

Nineteen patients (22%) developed postoperative infectious complications and fever was the most common one. E. faecalis, which is not responsive to common prophylaxis schemes in force in our institution, was the most frequent pathogen isolated. Overall, 26% of patients were found to have a discordance between SC and UC. At multivariable logistic regression analysis preoperative SC positivity (Odds Ratio [OR]: 11.00, 95% Confidence Interval [CI]:1.08-111.41, P=0.04) was the only significant predictor of postoperative infectious complications.

CONCLUSIONS

About one to five patients treated with URS developed an infectious complication and E. faecalis and E. coli were the most frequent pathogen isolated. A positive SC is the only independent risk factor for postoperative infection: consequently, an early SC analysis could allow a prompt antibiotic therapy in all patients with positive SC even if mildly symptomatic.

Defining a Molecular Signature for Uropathogenic versus Urocolonizing Escherichia coli: The Status of the Field and New Clinical Opportunities

Urinary tract infections (UTIs) represent a major burden across the population, although key facets of their pathophysiology and host interaction remain unclear. Escherichia coli epitomizes these obstacles: this gram-negative bacterial species is the most prevalent agent of UTIs worldwide and can also colonize the urogenital tract in a phenomenon known as asymptomatic bacteriuria (ASB). Unfortunately, at the level of the individual E. coli strains, the relationship between UTI and ASB is poorly defined, confounding our understanding of microbial pathogenesis and strategies for clinical management. Unlike diarrheagenic pathotypes of E. coli, the definition of uropathogenic E. coli (UPEC) remains phenomenologic, without conserved phenotypes and known genetic determinants that rigorously distinguish UTI- and ASB-associated strains. This article provides a cross-disciplinary review of the current issues from interrelated mechanistic and diagnostic perspectives and describes new opportunities by which clinical resources can be leveraged to overcome molecular challenges. Specifically, we present our work harnessing a large collection of patient-derived isolates to identify features that do (and do not) distinguish UTI- from ASB-associated E. coli strains. Analyses of biofilm formation, previously reported to be higher in ASB strains, revealed extensive phenotypic heterogeneity that did not correlate with symptomatology. However, metabolomic experiments revealed distinct signatures between ASB and cystitis isolates, including in the purine pathway (previously shown to be critical for intracellular survival during acute infection). Together, these studies demonstrate how large-scale, wild-type approaches can help dissect the physiology of colonization versus infection, suggesting that the molecular definition of UPEC may rest at the level of global bacterial metabolism.

Detection of microbial colonization of the urinary tract of patients prior to secondary ureterorenoscopy is highly variable between different types of assessment: results of a prospective observational study

This study compares the findings of different detection methods for microorganisms in patients with ureteral stents undergoing secondary ureterorenoscopy including the use of a novel validated examination pipeline for biofilms on ureteral stents. Of the included 94 patients, 21.3% showed bacteriuria in preoperative urine cultures. Intraoperative urine culture showed bacteriuria in four (4.3%) of the patients. Stent biofilm cultures were positive in 12.9% and qPCR detected bacterial DNA in 18.1%. The findings of the different examinations were poorly correlated with each other. Detection of microorganisms in the urinary tract of patients with indwelling ureteral stents is highly dependent on timing (i.e. pre- vs intraoperative) and method of assessment. Preoperative routine urine cultures are not predictive for intraoperative urine- and stent culture. These results cast doubt on the clinical relevance of enterococcal species, staphylococci, and streptococci if identified preoperatively prior to stent removal. The timing of oral preoperative antibiotic prophylaxis might need to be reconsidered.

Ureteral stents in urolithiasis

Ever since the ureteral stent design was fitted with a curl on both sides to prevent it from migrating up or down the ureter some 40 years ago, its use has gained tremendous momentum, aiding in the rise and evolution of endourology and has confidently kept its place in modern time urology. Over the past four decades, several designs, coating and biomaterials have been developed, trying to reduce infection, encrustation and other stent related symptoms. As the ideal stent has not yet been discovered, different ways of helping patients with their complaints have been researched. This review will cover these aspects of stent use in urolithiasis.

Outcomes of ureteral surgery and ureteral stenting in cats: 117 cases (2006-2014)

OBJECTIVE

To evaluate and compare outcomes in cats following ureteral surgery or ureteral stent placement.

DESIGN

Retrospective case series.

ANIMALS

117 cats.

PROCEDURES

Data regarding signalment, history, concurrent disease, clinical signs, clinicopathologic tests, surgical procedures, and perioperative complications (including death) were recorded. Follow-up data, including presence of signs of chronic lower urinary tract disease, chronic urinary tract infection, reobstruction, and death, if applicable, were obtained by records review or telephone contact with owners. Variables of interest were compared statistically between cats treated with and without stent placement. Kaplan-Meier analysis and Cox regression were performed to assess differences in survival time between cats with and without ureteral stents.

RESULTS

Perioperative complications referable to the urinary tract were identified in 6 of 43 (14%) cats that had ≥ 1 ureteral stent placed and 2 of 74 (3%) cats that underwent ureteral surgery without stenting. Perioperative mortality rates were similar between cats with (4/43 [9%]) and without (6/74 [8%]) stents. After surgery, signs of chronic lower urinary tract disease and chronic urinary tract infection were significantly more common among cats with than cats without stents. Nineteen of 87 (22%) cats with follow-up information available had recurrent obstruction; incidence of reobstruction did not differ between cats with and without stents. Median survival time did not differ between the 2 groups.

CONCLUSIONS AND CLINICAL RELEVANCE

The potential for signs of chronic lower urinary tract disease and chronic infection, particularly among cats that receive ureteral stents, warrants appropriate client counseling. Judicious long-term follow-up for detection of reobstruction is recommended.

Asymptomatic Bacteriuria and Bacterial Interference

Asymptomatic bacteriuria is very common. In healthy women, asymptomatic bacteriuria increases with age, from <1% in newborns to 10% to 20% of women age 80 years, but is uncommon in men until after age 50 years. Individuals with underlying genitourinary abnormalities, including indwelling devices, may also have a high frequency of asymptomatic bacteriuria, irrespective of age or gender. The prevalence is very high in residents of long-term-care facilities, from 25% to 50% of women and 15% to 40% of men. Escherichia coli is the most frequent organism isolated, but a wide variety of other organisms may occur. Bacteriuria may be transient or persist for a prolonged period. Pregnant women with asymptomatic bacteriuria identified in early pregnancy and who are untreated have a risk of pyelonephritis later in pregnancy of 20% to 30%. Bacteremia is frequent in bacteriuric subjects following mucosal trauma with bleeding, with 5% to 10% of patients developing severe sepsis or septic shock. These two groups with clear evidence of negative outcomes should be screened for bacteriuria and appropriately treated. Asymptomatic bacteriuria in other populations is benign and screening and treatment are not indicated. Antimicrobial treatment has no benefits but is associated with negative outcomes including reinfection with antimicrobial resistant organisms and a short-term increased frequency of symptomatic infection post-treatment. The observation of increased symptomatic infection post-treatment, however, has led to active investigation of bacterial interference as a strategy to prevent symptomatic episodes in selected high risk patients.

Urolithiasis in pregnancy: a cost-effectiveness analysis of ureteroscopic management vs ureteral stenting

OBJECTIVE

The purpose of this study was to determine the cost-effectiveness of serial stenting vs ureteroscopy for treatment of urolithiasis during pregnancy as a function of gestational age (GA) at diagnosis.

STUDY DESIGN

We built decision analytic models for a hypothetical cohort of pregnant women who had received a diagnosis of symptomatic ureteral calculi and compared serial stenting to ureteroscopy. We assumed ureteral stent replacement every 4 weeks during pregnancy, intravenous sedation for stent placement, and spinal anesthetic for ureteroscopy. Outcomes were derived from the literature and included stent infection, migration, spontaneous kidney stone passage, ureteral injury, failed ureteroscopy, postoperative urinary tract infection, sepsis, and anesthetic complications. Four separate analyses were run based on the GA at diagnosis of urolithiasis. Using direct costs and quality-adjusted life years, we reported the incremental costs and effectiveness of each strategy based on GA at kidney stone diagnosis and calculated the net monetary benefit. We performed 1-way and Monte-Carlo sensitivity analyses to assess the strength of the model.

RESULTS

Ureteroscopy was less costly and more effective for urolithiasis, irrespective of GA at diagnosis. The incremental cost of ureteroscopy increased from -$74,469 to -$7631, and the incremental effectiveness decreased from 0.49 to 0.05 quality-adjusted life years for a kidney stone diagnosed at 12 and 36 weeks of gestation, respectively. The net monetary benefit of ureteroscopy progressively decreased for kidney stones that were diagnosed later in pregnancy. The model was robust to all variables.

CONCLUSION

Ureteroscopy is less costly and more effective relative to serial stenting for urolithiasis, regardless of the GA at diagnosis. Ureteroscopy is most beneficial for women who received the diagnosis early during pregnancy.

Rate of positive urine culture and double-J catheters colonization on the basis of microorganism DNA analysis

Introduction

The aim of the trial was to estimate the relationship between colonization of the Double–J catheter, and the microorganisms cultured from urine.

Material and methods

60 patients, who had Double–J catheters inserted, participated in the study. All the subjects had their midstream urine samples taken prior to the stent insertion and removal. A negative urine culture before catheterization was mandatory to participate in the study. The patients were assigned into three subgroups, according to stenting duration: 1) 20 to 30 days (18 cases); 2) 30 to 90 days (30 cases); 3) longer than 90 days (12 cases). Bacterial and fungal DNA was identified using electrophoresis in polyacrylamide gel with a denaturing gradient (PCR–DGGE). The relationship between the genetic analysis of the catheter and the urine culture was estimated.

Results

Urine cultures were positive in only 8 patients, while Double–J catheter analyses were positive in all cases. In 2 cases one type of microorganism was isolated from the stent surface while the remaining 58 catheters were colonized by more than one pathogen. In three cases fungi were isolated. There were only three types of pathogens cultured from urine specimens. Urine and stent cultures were consistent in 5 cases. In 3 cases urine culture and stent analysis were not consistent.

Conclusions

Double–J catheter retention in the urinary tract is associated with an extremely high risk of bacterial colonization, while the risk of urine infection is about 8–fold lower. There is a great inconsistency between urine infection and catheter colonization, indicating a low predictive value of urine culture for estimating stent colonization.

Evaluation of a novel gel-based ureteral stent with biofilm-resistant characteristics

PURPOSE

Current ureteral stents, while effective at maintaining a ureteral lumen, provide a substrate for bacterial growth. This propensity for biofilm formation may be a nidus for bacterial growth leading to infection and a reason for early removal of a stent before it is clinically indicated. A newly devised stent, composed of a highly hydrated, partially hydrolyzed polyacrylonitrile polymer, is believed to have bacterial resistant properties. The objective of this study is to evaluate the biofilm growth and bacterial resistant properties of this novel stent.

MATERIALS AND METHODS

Multiple 1 cm sections of the pAguaMedicina™ Pediatric Ureteral Stent (pAMS) (Q Urological, Natick, MA) and the conventional polymer stent (SS) (Boston Scientific, Natick, MA) were incubated for 3 days in the 3 different growth media. Afterward, J96 human pathogenic Escherichia coli was added. At 3, 6, 9, 12, and 15 days following bacterial inoculation, the stent segments were washed, sonicated, and analyzed for bacterial growth. Scanning electron microscopy (SEM) imaging was performed to assess biofilm formation.

RESULTS

pAMS demonstrated significant reductions (43-71 %) in bacterial counts when compared to standard stents in all conditions tested. SEM imaging demonstrated biofilm formation on both types of stents in all media, with a relative reduction in apparent cell debris and bacteria on the pAMS.

CONCLUSIONS

In this study, the gel-based stent shows a demonstrable reduction in bacterial counts and biofilm formation. The use of the pAMS may reduce the risk of infection associated with stent usage.

Peri-interventional antibiotic prophylaxis only vs continuous low-dose antibiotic treatment in patients with JJ stents: a prospective randomised trial analysing the effect on urinary tract infections and stent-related symptoms

OBJECTIVE

To evaluate the antibiotic treatment regime in patients with indwelling JJ stents, the benefits and disadvantages of a peri-interventional antibiotic prophylaxis were compared with those of a continuous low-dose antibiotic treatment in a prospective randomised trial.

PATIENTS AND METHODS

In all, 95 patients were randomised to either receive peri-interventional antibiotic prophylaxis during stent insertion only (group A, 44 patients) or to additionally receive a continuous low-dose antibiotic treatment until stent removal (group B, 51). Evaluations for urinary tract infections (UTI), stent-related symptoms (SRSs) and drug side-effects were performed before stent insertion and consecutively after 1, 2 and 4 weeks and/or at stent withdrawal. All patients received a peri-interventional antibiotic prophylaxis with 1.2 g amoxicillin/clavulanic acid. Amoxicillin/clavulanic acid (625 mg) once daily was administered for continuous low-dose treatment (group B). Primary endpoints were the overall rates of UTIs and SRSs. Secondary endpoints were the rates and severity of drug side-effects.

RESULTS

Neither the overall UTI rates (group A: 9% vs group B: 10%), nor the rates of febrile UTIs (group A: 7% vs group B: 6%) were different between the groups. Similarly, SRS rates did not differ (group A: 98% vs group B: 96%). Antibiotic side-effect symptoms were to be increased in patients treated with low-dose antibiotics.

CONCLUSION

A continuous antibiotic low-dose treatment during the entire JJ stent-indwelling time does not reduce the quantity or severity of UTIs and has no effect on SRSs either compared with a peri-interventional antibiotic prophylaxis only.

Complications and outcomes of JJ stenting of the ureter in urological practice: A single-centre experience

Objective

To determine the factors affecting the development of complications and the outcomes of JJ stenting.

Patients and methods

The study included 220 patients (133 males and 87 females, mean age 39.5 years, SD 15.4) who had self-retaining JJ ureteric stents placed while in the authors’ institution. Univariate and multivariate analyses were used to identify the significant variables affecting the development of complications and outcome of stenting (condition ‘improved’ or ‘not improved’).

Results

Using a modified Clavien classification, there were grade I, II, IIIa, IIIb complications in 67 (30.4%), 39 (17.7%), two (0.9%) and 23 (10.5%) patients, respectively, and none of grades IVa, IVb and V. Loin pain (10.9%) and urinary tract infection (10.9%) were the most common complications, followed by dysuria (7.7%). There were significant complications requiring treatment in 29% of patients, and 71.4% of patients improved after stenting. On multivariate analysis the significant independent factor affecting the complication rate was the stent length (P = 0.016), and the significant independent factor affecting the ‘improved’ outcome was age (P = 0.014).

Conclusion

Longer stents are associated with increased complication rates, and the older the patient the more likely they are to have a poor outcome after stenting. Future prospective multicentre studies with more patients are needed to confirm the present conclusions.

Antimicrobial prophylaxis in noncardiac prosthetic device recipients

BACKGROUND

Secondary antimicrobial prophylaxis involves the use of ≥ 1 antimicrobial agent just prior to the time when a diagnostic/therapeutic procedure, which may induce infection, is to be performed. In the context of this article, antimicrobial agent(s) are administered to patients with ≥ 1 implanted prosthetic device in order to prevent metastatic seeding of the device(s) during bacteremia induced by a diagnostic/therapeutic procedure. Antimicrobial agents used in this context are only administered periprocedurally. Secondary antimicrobial prophylaxis of endocarditis in recipients of cardiac prosthetic materials (including valves, shunts, conduits, and patches) has been reasonably well established. However, secondary antimicrobial prophylaxis in recipients of other types of prosthetic devices has been the subject of much controversy, with a wide variety of recommendations being made.

OBJECTIVES

The purpose of this article was to conduct a narrative review of the published literature on the topic of secondary antimicrobial prophylaxis in recipients of noncardiac prosthetic devices and make evidence-based recommendations for each type of device, where possible.

METHODS

Medline/PubMed and EMBASE databases were searched for English-language articles published from 1950 to the present (January 2012). Search terms included "prophylaxis," "antibiotics," "antimicrobials," "prosthetic devices," "prosthesis-related infections," "bacteremia," the names of the individual types of prosthetic devices, and the names of the individual procedures potentially inducing bacteremia. Articles dealing with any aspect relevant to this topic were eligible for review. The bibliographies of retrieved articles were also carefully scanned to identify any articles not previously identified.

RESULTS

Based on review of the available literature, secondary antimicrobial prophylaxis is justified in only a few specific circumstances. For recipients of prosthetic vascular grafts/stents, hemodialysis arteriovenous shunts, and ventriculoatrial/ventriculovenous shunts, prophylaxis is warranted during the initial 6 months, initial 6 weeks, and at all times after implantation/revision, respectively, when dental procedures capable of inducing high-level bacteremia are planned. Prosthetic joint recipients should receive prophylaxis in the following 3 circumstances: 1) patient is to undergo dental procedure(s) capable of inducing high-level bacteremia plus either the patient is still within 2 years of device implantation/revision or the patient has ≥ 1 risk factor for hematogenous prosthetic joint infection; 2) patient is to undergo genitourinary tract procedure(s) capable of inducing high-level bacteremia plus the patient has ≥ 1 risk factor for high-risk bacteriuria; and 3) patient is to undergo perforating dermatologic surgery on the oral mucosa or at skin sites at increased risk for surgical site infection plus patient has ≥ 1 risk factor for hematogenous prosthetic joint infection. The data are inadequate to justify secondary antimicrobial prophylaxis for recipients of other types of prosthetic devices. On the basis of 9 surveys of prescriber behavior, it is apparent that there exists, over a wide geographic area, a wide disconnect between clinical practice and the secondary antimicrobial prophylaxis guidelines issued by the professional organizations representing these prescribers. Antimicrobial agent overuse was especially problematic among orthopedic and colorectal surgeons, urologists, and family practitioners. Dentists and maxillofacial surgeons followed guidelines more closely.

CONCLUSION

Device-, procedure-, and patient characteristic-dependent factors elicited over many years have narrowed down the secondary antimicrobial prophylaxis recommendations for noncardiac prosthetic devices to a small number. Despite this, physician prescribers frequently do not follow prophylaxis guidelines established by their own professional organizations. Risk-benefit and cost-effectiveness studies have found that no prophylaxis is actually superior to universal prophylaxis, likely due to known antimicrobial toxicities, such as anaphylactic/anaphylactoid reactions and Clostridium difficile-associated disease. Much work remains in establishing and extending the scientific basis for secondary antimicrobial prophylaxis and transforming this knowledge into appropriate action by the clinician.

Update on ureteral stent technology

Ureteral stents are commonly used in urology but are frequently associated with patient discomfort, stent encrustation and stent-related infection. New biomaterials, coatings and designs have been designed to attempt to reduce these problems. This article reviews coatings to reduce bacterial adhesion and encrustation. In addition, metal ureteral stents, the triclosan and ketorolac drug eluting ureteral stents, and biodegradable ureteral stents are discussed. In summary there is no perfect ureteral stent that avoids all morbidity but there have been significant advances in the last few years in stent technology.