The use of triclosan eluting stents effectively reduces ureteral stent symptoms: a prospective randomized trial

Role of ureteral stent material and coating to prevent ureteral stent related issue: A systematic review and meta analysis

INTRODUCTION

Ureteral stents require materials that balance bulk and surface properties. Achieving both can be challenging, as ideal bulk properties may not align with optimal surface properties. Thus, researching coatings and biomanufacturing methods for ideal materials is essential.

METHODS

A systematic review and meta-analysis, following PRISMA Guidelines, involved literature searches across five databases: PubMed, Scopus, Embase, ClinicalKey, and Cochrane. From 417 screened articles, eight studies were deemed eligible for qualitative and quantitative analysis. The selected articles underwent bias assessment using ROB Tools 2.

RESULTS

The systematic review analyzed 1.356 participants. Findings revealed that firm ureteral stents significantly increased risk of infection, hematuria, and lower body pain. On the contrary, soft stents reduced infection (OR: 0.62; p=0.004), hematuria (OR: 0.60; p<0.001), and lower body pain (OR: 0.63; p=0.0002). However, infection reduction effect was uncertain due to heterogeneity. Coated vs non-coated material analysis found no difference in encrustation (OR: 1.26; p=0.52) or infection (OR: 1.67; p=0.99). Stent firmness did not affect encrustation on double J stent (OR: 0.97; p=0.17).

CONCLUSIONS

Softer materials like silicone are preferred for ureteral stents to reduce symptoms like hematuria and lower body pain. Coatings like silver nanoparticles and triclosan, while enhancing antimicrobial properties, did not effectively lower infection risk.

A Prospective, Randomized Controlled Multicenter Trial Comparing the Bard Inlay Optima and the Cook Universa Soft Stent

OBJECTIVE

To determine if the Bard Inlay Optima with its anti-inflammatory pHreecoat stent coating had reduced stent-related symptoms at Week 1 (W1) and Week 3 (W3) post insertion compared to the Cook Universa Soft (CUS) using the validated Ureteral Stent Symptoms Questionnaire (USSQ).

METHODS

A prospective, double-blinded, randomized controlled trial was performed on patients receiving unilateral retrograde double-J stents for urolithiasis or pelviureteric junction obstruction at three public Urology services. One hundred forty patients that met inclusion criteria were randomized in a 1:1 ratio to each stent. Primary endpoints were the mean USSQ index scores for the urinary, pain, general, and sexual health domains at W1 and W3. Secondary endpoints were responses to individual USSQ questions, early stent removal, and postoperative opioid use.

RESULTS

No significant difference was found between the two stents in terms of index scores for all USSQ domains, early stent removal or postoperative opioid use. The CUS had worse symptom scores at W1 relating to self-reported urinary tract infection symptoms (3.1 ± 1.3 vs 2.6 ± 1.3, P = .05). The CUS was also associated with higher rate of representation to hospital at W1 (n = 10, 16% vs n = 1, 2%, P < .001) and W3 (n = 15, 25% vs n = 3, 5%, P < .001). This did not remain significant when adjusted to site of recruitment (W1 P = .27; W3 P = .22).

CONCLUSION

The Bard Inlay Optima's anti-inflammatory pHreecoat stent coating did not translate to any significant difference in overall postoperative symptoms across urinary, pain, general, and sexual health domains.

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.

Antimicrobial and Antiproliferative Coatings for Stents in Veterinary Medicine-State of the Art and Perspectives

Microbial colonization in veterinary stents poses a significant and concerning issue in veterinary medicine. Over time, these pathogens, particularly bacteria, can colonize the stent surfaces, leading to various complications. Two weeks following the stent insertion procedure, the colonization becomes observable, with the aggressiveness of bacterial growth directly correlating with the duration of stent placement. Such microbial colonization can result in infections and inflammations, compromising the stent's efficacy and, subsequently, the animal patient's overall well-being. Managing and mitigating the impact of these pathogens on veterinary stents is a crucial challenge that veterinarians and researchers are actively addressing to ensure the successful treatment and recovery of their animal patients. In addition, irritation of the tissue in the form of an inserted stent can lead to overgrowth of granulation tissue, leading to the closure of the stent lumen, as is most often the case in the trachea. Such serious complications after stent placement require improvements in the procedures used to date. In this review, antibacterial or antibiofilm strategies for several stents used in veterinary medicine have been discussed based on the current literature and the perspectives have been drawn. Various coating strategies such as coating with hydrogel, antibiotic, or other antimicrobial agents have been reviewed.

Impact of Ureteral Stent Material on Stent-related Symptoms: A Systematic Review of the Literature

Context

Ureteral stents are essential implants that are used on a daily basis. Since their invention, advances in stent design have been directed towards alleviating stent-related symptoms. It remains unclear how the material composition of the stent affects stent-related symptoms.

Objective

To review the literature and define the clinical impact of ureteral stent material on stent-related symptoms.

Evidence acquisition

A literature search of the Embase, MEDLINE (PubMed), and Web of Science databases was conducted on December 17, 2021 to collect articles comparing stent composition materials regarding stent-related symptoms. Thirteen publications met the inclusion criteria, of which only one met the high-quality requirements of the Cochrane Collaboration tool for assessing the risk of bias in randomized trials.

Evidence synthesis

Most trials, including the highest quality trial, seem to support that silicone double-J (DJ) stents reduce stent-related symptoms compared to nonsilicone DJ stents. Regarding physical properties, it seems that “soft” or “flexible” DJ stents reduce stent-related symptoms. However, since there was only one high-quality study with a low risk of bias, it is impossible to draw a definitive conclusion owing to the lack of quality data.

Conclusions

Silicone DJ stents, and by extension “soft” DJ stents, appear to reduce stent-related symptoms compared to nonsilicone polymers and “hard” DJ stents. No definitive conclusion can be drawn owing to a lack of quality evidence. Creating a standard for measuring and reporting physical stent properties should be the first step for further research.

Patient summary

A ureteral stent is a small hollow tube placed inside the ureter to help urine drain from the kidney. We reviewed the literature on the impact of stent material on stent-related symptoms. We found that silicone may reduce stent-related symptoms, but no definitive conclusion can be drawn and further studies are needed.

Bioengineering solutions for Ureteric disorders: Clinical need, challenges and opportunities

Objectives

To summarise the causes of ureteric damage and the current standard of care, discussing the risks and benefits of available therapeutic options. We then focus on the current and future solutions that can be provided by ureteric bioengineering and provide a description of the ideal characteristics of a bioengineered product.

Methods

We performed a literature search in February 2021 in: Google Scholar, Medline, and Web of Science. Three searches were conducted, investigating: (a) the epidemiology of ureteric pathology, (b) the current standard of care, and (c) the state of the art in ureteric bioengineering.

Results

The most‐common causes of ureteric damage are iatrogenic injury and external trauma. Current approaches to treatment include stent placement or surgical reconstruction. Reconstruction can be done using either urological tissue or segments of the gastrointestinal tract. Limitations include scarring, strictures, and infections. Several bioengineered alternatives have been explored in animal studies, with variations in the choice of scaffold material, cellular seeding populations, and pre‐implantation processing. Natural grafts and hybrid material appear to be associated with superior outcomes. Furthermore, seeding of the scaffold material with stem cells or differentiated urothelial cells allows for better function compared to acellular scaffolds. Some studies have attempted to pre‐implant the graft in the omentum prior to reconstruction, but this has yet to prove any definitive benefits.

Conclusion

There is an unmet clinical need for safer and more effective treatment for ureteric injuries. Urological bioengineering is a promising solution in preclinical studies. However, substantial scientific, logistic, and economic challenges must be addressed to harness its transformative potential in improving outcomes.

Surgical Applications of Materials Engineered with Antimicrobial Properties

The infection of surgically placed implants is a problem that is both large in magnitude and that broadly affects nearly all surgical specialties. Implant-associated infections deleteriously affect patient quality-of-life and can lead to greater morbidity, mortality, and cost to the health care system. The impact of this problem has prompted extensive pre-clinical and clinical investigation into decreasing implant infection rates. More recently, antimicrobial approaches that modify or treat the implant directly have been of great interest. These approaches include antibacterial implant coatings (antifouling materials, antibiotics, metal ions, and antimicrobial peptides), antibacterial nanostructured implant surfaces, and antibiotic-releasing implants. This review provides a compendium of these approaches and the clinical applications and outcomes. In general, implant-specific modalities for reducing infections have been effective; however, most applications remain in the preclinical or early clinical stages.

New Stent Technologies

Ureteral stents are an indispensable part of any (endo-) urologic practice. Despite the widely demonstrated advantages of stents, they also carry a considerable risk of side effects and complications, such as urinary symptoms, pain, hematuria, decreased quality of life, stent-related infection, and encrustation. Multiple pathways in preventing or mitigating these side effects and complications and improving stent efficacy have been and are being investigated, including stent architecture and design, biomaterials, and coatings. This article provides an update on currently researched and available stents as well as future perspectives.

Drug-delivering devices in the urinary tract: A systematic review

Objective

: To systematically review the use of drug-eluting stents (DES) and drug-coated balloons (DCB) in urology.

Materials and Methods

The systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, Scopus, Web of science and Cochrane Library online databases were searched in February 2019. Experimental and clinical studies, which included the placement of a DES or dilatation with DCB for investigating their potential use in the urinary tract for the management of ureteric or urethral pathologies, were included. The primary endpoint was to evaluate the current use of DES and DCB in urology.

Results

A total of 29 articles were included in the systematic review. A total of 10 studies tested DES or DCB containing anti-proliferative agents (paclitaxel, zotarolimus, sirolimus, halofugione). Antibiotic agent-containing DES were tested in nine studies (triclosan, quinolones, teicoplanin, nitrofurantoin, silver sulfadiazine). A total of eight studies investigated the release of anti-inflammatory agents by DES (ketorolac, indomethacin, EW-7197). Another group studied heparin-eluting stents.

Conclusion

Despite the inconclusive outcomes of the three randomised controlled trials, drug-coated/eluting devices constitute a promising field in urology for the prevention of complications associated with conventional stents including pain and encrustation. Pre-clinical in vitro and in vivo studies have shown their ability to mitigate inflammation, inhibit re-stenosis and improve pain as indicated by declined use of anti-inflammatory drugs.

Abbreviations: DES: drug-eluting stents; DCB: drug-coated balloons; DCS: drug-coated stents; HF: halofungione; MCP-1: monocyte chemoattractant protein 1; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses; PTCA: percutaneous transluminal coronary angioplasty; RANTES: regulated on activation, normal T-cell expressed and secreted; RCT: randomised controlled trial; USSQ, Ureteric Stent Symptoms Questionaire.

Triclosan: antimicrobial mechanisms, antibiotics interactions, clinical applications, and human health

The large-scale applications of Triclosan in industrial and household products have created many health and environmental concerns. Despite the fears of its drug-resistance and other issues, Triclosan is still an effective drug against many infectious organisms. Knowing the cross-interactions of Triclosan with different antibiotics, bacteria, and humans can provide much-needed information for the risk assessment of this drug. We review the current understanding of the antimicrobial mechanisms of Triclosan, how microbes become resistant to Triclosan, and the synergistic and antagonistic effects of Triclosan with different antibiotics. Current literature on the clinical applications of Triclosan and its effect on fetus/child development are also summarized.

Ureteric stents: Overview of current clinical applications and economic implications

Ureteric stents are one of the most crucial tools used for various clinical conditions in the urological field. Placement of a ureteric stent, for short- or long-term use, remains one of the commonest urological interventional procedures. In the past few decades, ureteral stents have undergone notable technological advancements. However, an ideal stent without significant side-effects is yet to be engineered. Indwelling ureteric stents are often accompanied by physical distress to the patient and clinical complications, such as bacterial adhesion, encrustation, malpositioning, stent fracture and forgotten stent syndrome, that influence patients' health-related quality of life. In the market, different stent types are available, designed to reduce infections, and improve patient symptoms and tolerance. In this review, we have emphasized the recent developments that have taken place in stent design, size, materials and coating. This overview looks at current practices and problems related to stents, along with clinical and economic considerations. Few trial studies have been enumerated in the context of utilization of a ureteral stent symptom questionnaire and various stent models to compare their effects in patients.

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.

Ureteric Stent Use - Part of the Solution and Part of the Problem

Background

The aim of the study is to comprehensively report on a single tertiary referral center experience with the use of ureteric stents, assess complication burden and determine risk factors to further inform institutional practice.

Materials and Methods

The retrospectively analyzed cohorts includes 529 patients treated over a 12 months period. Data regarding details of the index pathology, stent characteristics and complications were collected retrospectively.

Results

Most stents (58.9%) were used in the context of stone surgery. Stent encrustation occurred in 14.5% of patients and sepsis in 4.3%. There was a statistically significant difference between the complications of the stents removed after 90 days and the rest of the cohort. Infectious complications were more frequent in diabetic patients and in patients with chronic renal impairment. At our institution, we managed to avoid forgotten stents and catastrophic complications.

Conclusion

Stent complications are the complex outcome of interplay between the foreign body and the collecting system environment, influenced by the nature and timing of surgery. Longer stent dwelling times are associated with increased complications rates, especially in patients with significant comorbidities.

A bilayer swellable drug-eluting ureteric stent: Localized drug delivery to treat urothelial diseases

A bilayer swellable drug-eluting ureteric stent (BSDEUS) is engineered and implemented, as a sustained drug delivery platform technology that enhances localized drug delivery to the highly impermeable urothelium, for the treatment of urothelial diseases such as strictures and carcinomas. On deployment, the device swells to co-apt with the ureteric wall and ensure drug availability to these tissues. BSDEUS consists of a stent spray-coated with a polymeric drug containing polylactic acid-co-caprolactone (PLC) layer which is overlaid by a swellable polyethylene glycol diacrylate (PEGDA) based hydrogel. In-vitro quantification of released drug demonstrated a tunable time-profile, indicating sustained delivery over 1-month. The PEGDA hydrogel overlayer enhanced drug release and transport into explanted porcine ureteric tissues ex-vivo, under a simulated dynamic fluid flow. A preliminary pilot in-vivo feasibility study, in a porcine model, demonstrated that the swollen hydrogel co-apts with the urothelium and thus enables localized drug delivery to the target tissue section. Kidney functions remained unaffected and device did not result in either hydronephrosis or systemic toxicity. This successful engineering of a bilayer coated stent prototype, demonstrates its feasibility, thus offering a unique solution for drug-based urological therapy.

A randomized controlled trial comparing antimicrobial (silver sulfadiazine)-coated ureteral stents with non-coated stents

OBJECTIVE

The aim of this study was to compare the efficacy of antimicrobial [silver sulfadiazine (SSD)]-coated ureteral stents with non-coated stents in the prevention of stent-related bacteriuria.

MATERIALS AND METHODS

A randomized controlled trial was conducted between September 2014 and September 2016 after approval from the local ethics committee. Inclusion criteria were adults who underwent unilateral double-J ureteral stent placement after ureteroscopic lithotripsy. All patients underwent placement of the same stent type (Carbothan^® with hydrophilic surface) and dimensions (6 F, 26 cm). In the test group, stents were coated with SSD. Patients who used antibiotics during the stenting period or underwent stent removal elsewhere were excluded from the study. Urine and stent cultures were obtained on the day of stent removal. All patients answered the Ureteral Stent Symptom Questionnaire (USSQ).

RESULTS

The study included 126 patients. The mean ± SD stent duration was 3.1 ± 1.2 weeks. There were no significant differences between groups in the incidence of bacteriuria and USSQ scores. However, two stents (3.2%) in the SSD group had significant bacterial growth, compared to eight stents (12.5%) in the control group (p = 0.054). The incidence of newly diagnosed bacteriuria was higher in the control group (11%) than the antimicrobial group (6.5%), but the difference was not significant (p = 0.372).

CONCLUSIONS

This study could not justify the use of antimicrobial (SSD)-coated stents for short stenting periods. The trend towards decreasing stent colonization in the antimicrobial group was not translated to a significantly lower incidence of stent-related bacteriuria or improvement in patients' quality of life.

Drug-eluting biodegradable ureteral stent: New approach for urothelial tumors of upper urinary tract cancer

Upper urinary tract urothelial carcinoma (UTUC) accounts for 5-10% of urothelial carcinomas and is a disease that has not been widely studied as carcinoma of the bladder. To avoid the problems of conventional therapies, such as the need for frequent drug instillation due to poor drug retention, we developed a biodegradable ureteral stent (BUS) impregnated by supercritical fluid CO₂ (scCO₂) with the most commonly used anti-cancer drugs, namely paclitaxel, epirubicin, doxorubicin, and gemcitabine. The release kinetics of anti-cancer therapeutics from drug-eluting stents was measured in artificial urine solution (AUS). The in vitro release showed a faster release in the first 72h for the four anti-cancer drugs, after this time a plateau was achieved and finally the stent degraded after 9days. Regarding the amount of impregnated drugs by scCO₂, gemcitabine showed the highest amount of loading (19.57μg _drug/mg _polymer: 2% loaded), while the lowest amount was obtained for paclitaxel (0.067μg _drug/mg _polymer: 0.01% loaded). A cancer cell line (T24) was exposed to graded concentrations (0.01-2000ng/ml) of each drugs for 4 and 72h to determine the sensitivities of the cells to each drug (IC₅₀). The direct and indirect contact study of the anti-cancer biodegradable ureteral stents with the T24 and HUVEC cell lines confirmed the anti-tumoral effect of the BUS impregnated with the four anti-cancer drugs tested, reducing around 75% of the viability of the T24 cell line after 72h and demonstrating minimal cytotoxic effect on HUVECs.

Ureteral stent technology: Drug-eluting stents and stent coatings

Ureteral stents are commonly used following urological procedures to maintain ureteral patency. However, alongside the benefits of the device, indwelling stents frequently cause significant patient discomfort (pain, urgency, frequency) and can become encrusted and infected. The importance of these sequelae is that they are not only bothersome to the patient but can lead to significant morbidity, urinary retention, ureteral damage, recurrent infections, pyelonephritis and sepsis. When these problems occur, stent removal or replacement alongside antibiotic, analgesic and/or other symptom-modifying therapies are essential to successfully treat the patient. In an attempt to prevent such morbidity, numerous approaches have been investigated over the past several decades to modify the stent itself, thereby affecting changes locally within the urinary tract without significant systemic therapy. These strategies include changes to device design, polymeric composition, drug-elution and surface coatings. Of these, drug-elution and surface coatings are the most studied and display the most promise for advancing ureteral stent use and efficacy. This article reviews these two strategies in detail to determine their clinical potential and guide future research in the area.

A Prospective Randomized Trial Comparing Pneumatic Lithotripsy and Holmium Laser for Management of Middle and Distal Ureteral Calculi

PURPOSE

The aim of this study was to compare the efficacy and safety between pneumatic and holmium:yttrium-aluminum-garnet (Ho:YAG) laser in the treatment of patients with ureteral stones located in the middle and distal ureter.

PATIENTS AND METHODS

We conducted a prospective study in recruiting 982 eligible patients from 2009 to 2012. Patients were randomly divided into two groups-the pneumatic lithotripsy (PL) group or the Ho:YAG laser lithotripsy (LL) group. Patient demographics, stone characteristics, intraoperative parameters, and postoperative complications were evaluated and analyzed.

RESULTS

The baseline demographics of patients and stone characteristics were similar in the two groups. The LL group showed significant benefits compared with the PL group in terms of mean operative time (28±9.2 vs 41±12.4 min, P=0.001) and early stone-free rate (80.8% vs 91.3%, P=0.04), but there was no statistically significant difference at the third month (92.6% vs 95.5%, P=0.15). In the LL group, 24 postoperative cases of stricture were seen, whereas only 5 cases occurred in the PL group (P=0.02). The other complications, such as perforation, bleeding, and mucosal injury, were comparable in the two groups. The average postoperative stay was also similar (1.7±2.4 days for PL and 1.5±3.1 days for LL (P=0.62).

CONCLUSION

Both PL and LL are effective in the management of middle and distal impacted stones. Ho:YAG laser has advantages in better efficacy of stone fragmentation and a higher early stone-free rate but seems to have to face the increased risks of postoperative stricture.

Ureteral stent-associated complications--where we are and where we are going

Ureteral stents are one of the most commonly used devices in the treatment of benign and malignant urological diseases. However, they are associated with common complications including encrustation, infection, pain and discomfort caused by ureteral tissue irritation and possibly irregular peristalsis. In addition, stent migration and failure due to external compression by malignancies or restenosis occur, albeit less frequently. As these complications restrict optimal stent function, including maintenance of adequate urine drainage and alleviation of hydronephrosis, novel stent materials and designs are required. In recent years, progress has been made in the development of drug-eluting expandable metal stents and biodegradable stents. New engineering technologies are being investigated to provide stents with increased biocompatibility, decreased susceptibility to encrustation and improved drug-elution characteristics. These novel stent characteristics might help eliminate some of the common complications associated with ureteral stenting and will be an important step towards understanding the behaviour of stents within the urinary tract.

The use of internal stents in chronic ureteral obstruction

PURPOSE

Despite the lack of a well delineated definition, chronic ureteral obstruction imposes significant quality of life loss, increased pathological morbidity and risk of mortality as well as substantial economic burden. Ureteral stenting serves as an important therapeutic option to alleviate obstruction. Thus, we assessed the recently published literature on chronic ureteral obstruction; treatment options; types, benefits and shortcomings of current ureteral stents; as well as outcomes and complications of chronic ureteral stenting, with the goal of providing concise management guidelines.

MATERIALS AND METHODS

A systemic literature review was performed on Embase™, PubMed®, Cochrane Controlled Trials Register and Google Scholar™ on ureteral obstruction and internal ureteral stents. Relevant reviews, original research articles and their cited references were examined, and a synopsis of original data was generated on a clinically oriented basis.

RESULTS

Chronic ureteral obstruction can be classified into compression that is either intrinsic or extrinsic to the ureteral wall, or obstruction that is of a benign or malignant origin. Patients with malignant ureteral obstruction generally have a poor prognosis and are often difficult to treat. The aim of stenting is to adequately drain the upper urinary tracts while minimizing hospitalization and the negative impact on quality of life. Facing the challenge of chronic ureteral obstruction, novel stents with new compositions, materials, coatings and designs have been developed. Metallic stents are emerging as efficacious and financially viable alternatives. Early stent related complications include iatrogenic injury, stent migration or patient discomfort, while late complications include infection, difficulties with stent exchange, hardware malfunction, infection and stent encrustation.

CONCLUSIONS

Stenting in chronic ureteral obstruction is a complex and challenging problem. Much work is being done in this area and many options are being explored.

Drug-eluting metallic stents in urology

Drugeluting metal stents (DESs) have been extensively used in coronary and vascular disease. This type of stents has been proven to provide significantly lower restenosis rates due to the reduction of neo-intimal hyperplasia in comparison to the traditionally used bare metal stents (BMSs). The latter stents have been evaluated for more than a decade in urological practice in an attempt to provide permanent relief of urethral or ureteral obstruction. Although the initial results were promising, long-term experience revealed significant complications, which are mainly attributed to stent-related hyperplastic reaction compromising stent patency. The favorable experience of vascular DESs led to the application of DESs in both the urethra and ureter of animal models. These experimental results demonstrated a reduction of hyperplastic reaction of DESs in comparison to BMSs. Nevertheless, clinical data are currently not available. Considering the fact that DESs are under continuous development, the use of DESs in urology holds promise for the future and seems to be an intriguing field.

Antifouling coating with controllable and sustained silver release for long-term inhibition of infection and encrustation in urinary catheters

Urinary tract infections constitute a large proportion of nosocomial infections, and the urinary catheter is the most important predisposing factor. Encrustation induced by urease-producing uropathogens like Proteus mirabilis causes further complications. In the present work, a strategy for controllable and sustained release of silver over several weeks has been developed for combating bacterial infection and encrustation in urinary devices. Silver nanoparticles (AgNPs) were first immobilized on polydopamine (PDA) pre-treated silicone catheter surface and this was followed by another PDA coating. The number of AgNP-PDA bilayers could be manipulated to control the amount of silver loaded and its subsequent release. Poly(sulfobetaine methacrylate-co-acrylamide) was then grafted to provide an antifouling outer layer, and to ensure free diffusion of Ag from the surface. The micron-scale combination of an antifouling coating with AgNP-PDA bilayers reduced colonization of the urinary catheter by uropathogens by approximately two orders of magnitude. With one and two AgNP-PDA bilayers, the coated catheter could resist encrustation for 12 and 45 days, respectively, compared with approximately 6 days with the Dover™ silver-coated catheter. Such anti-infective and anti-encrustation catheters can potentially have a large impact on reducing patient morbidity and healthcare expenditure.

Comparison of the roll-plate and sonication techniques in the diagnosis of microbial ureteral stent colonisation: results of the first prospective randomised study

BACKGROUND

Microbial ureteral stent colonisation (MUSC) is one leading risk factor for complications associated with ureteral stent placement. As MUSC remains frequently undetected by standard urine cultures, its definitive diagnosis depends on microbiological investigation of the stent. However, a standard reference laboratory technique for studying MUSC is still lacking.

MATERIALS AND METHODS

A total of 271 ureteral stents removed from 199 consecutive patients were investigated. Urine samples were obtained prior to device removal. Stents were divided into four parts. Each part was separately processed by the microbiology laboratory within 6 h. Ureteral stents were randomly allocated to roll-plate or sonication, respectively, and analysed using standard microbiological techniques. Demographic and clinical data were prospectively collected using a standard case-report form.

RESULTS

Overall, roll-plate showed a higher detection rate of MUSC compared with sonication (35 vs. 28 %, p < 0.05) and urine culture (35 vs. 8 %, p < 0.05). No inferiority of Maki's technique was observed even when stents were stratified according to indwelling time below or above 30 days. Compared with roll-plate, sonication commonly failed to detect Enterococcus spp., coagulase-negative staphylococci (CoNS) and Enterobacteriaceae. In addition, sonication required more hands-on time, more equipment and higher training than roll-plate in the laboratory.

CONCLUSIONS

This prospective randomised study demonstrates the superiority of Maki's roll-plate technique over sonication in the diagnosis of MUSC and that urine culture is less sensitive than both methods. The higher detection rate, simplicity and cost-effectiveness render roll-plate the methodology of choice for routine clinical investigation as well as basic laboratory research.