Novel antiseptic urinary catheters for prevention of urinary tract infections: correlation of in vivo and in vitro test results

Advances in experimental bladder models: bridging the gap between in vitro and in vivo approaches for investigating urinary tract infections

Urinary tract infections (UTIs) pose a substantial burden on global healthcare systems. When unraveling the complex pathophysiology of UTIs, bladder models are used to understand complex and multifaceted interactions between different components within the system. This review aimed to bridge the gap between in vitro and in vivo experimental bladder models towards UTI research. We reviewed clinical, animal, and analytical studies and patents from 1959 to the end of 2023. Both in vivo and in vitro models offer unique benefits and drawbacks in understanding UTIs. In vitro models provide controlled environments for studying specific aspects of UTI biology and testing potential treatments, while in vivo models offer insights into how UTIs manifest and progress within living organisms. Thus, both types of models are leading to the development of more effective diagnostic tools and therapeutic interventions against UTIs. Moreover, advanced methodologies involving three-dimensional bladder organoids have also been used to study bladder biology, model bladder-related disorders, and explore new treatments for bladder cancers, UTIs, and urinary incontinence. Narrowing the distance between fundamental scientific research and practical medical applications, these pioneering models hold the key to unlocking new avenues for the development of personalized diagnostics, precision medicine, and ultimately, the alleviation of UTI-related morbidity worldwide.

A comprehensive status update on modification of foley catheter to combat catheter-associated urinary tract infections and microbial biofilms

Present-day healthcare employs several types of invasive devices, including urinary catheters, to improve medical wellness, the clinical outcome of disease, and the quality of patient life. Among urinary catheters, the Foley catheter is most commonly used in patients for bladder drainage and collection of urine. Although such devices are very useful for patients who cannot empty their bladder for various reasons, they also expose patients to catheter-associated urinary tract infections (CAUTIs). Catheter provides an ideal surface for bacterial colonization and biofilm formation, resulting in persistent bacterial infection and severe complications. Hence, rigorous efforts have been made to develop catheters that harbour antimicrobial and anti-fouling properties to resist colonization by bacterial pathogens. In this regard, catheter modification by surface functionalization, impregnation, blending, or coating with antibiotics, bioactive compounds, and nanoformulations have proved to be effective in controlling biofilm formation. This review attempts to illustrate the complications associated with indwelling Foley catheters, primarily focussing on challenges in fighting CAUTI, catheter colonization, and biofilm formation. In this review, we also collate scientific literature on catheter modification using antibiotics, plant bioactive components, bacteriophages, nanoparticles, and studies demonstrating their efficacy through in vitro and in vivo testing.

Emerging evidence-based innovative approaches to control catheter-associated urinary tract infection: a review

Healthcare settings have dramatically advanced the latest medical devices, such as urinary catheters (UC) for infection, prevention, and control (IPC). The continuous or intermittent flow of a warm and conducive (urine) medium in the medical device, the urinary catheter, promotes the formation of biofilms and encrustations, thereby leading to the incidence of CAUTI. Additionally, the absence of an innate immune host response in and around the lumen of the catheter reduces microbial phagocytosis and drug action. Hence, the review comprehensively overviews the challenges posed by CAUTI and associated risks in patients' morbidity and mortality. Also, detailed, up-to-date information on the various strategies that blended/tailored the surface properties of UC to have anti-fouling, biocidal, and anti-adhesive properties to provide an outlook on how they can be better managed with futuristic solutions.

Combating Bacterial Biofilm Formation in Urinary Catheter by Green Silver Nanoparticle

Urinary catheters are commonly associated with urinary tract infections. This study aims to inhibit bacterial colonisation and biofilm of urinary tract catheters. Silicon catheter pieces were varnished with green silver nanoparticles (AgNPs) using Pistacia lentiscus mastic to prevent bacterial colonisation. Pomegranate rind extract was used to synthesize AgNPs. AgNPs were characterized by UV-Vis spectroscopy, X-ray crystallography, and transmission electron microscopy (TEM). Results obtained revealed that the size of most AgNPs ranged between 15–25 nm and they took crystallised metal and oxidised forms. The amounts of released silver ions from 1 cm pieces of catheters coated with AgNPs were estimated for five days and ranged between 10.82 and 4.8 µg. AgNPs coated catheters significantly inhibited the colonisation of catheters by antibiotic-resistant clinical Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa) bacteria. AgNPs-varnish was more active against Gram-negative bacteria than Gram-positive bacteria. The significant inhibitory effect of coated catheters lasted for 72 h for both Gram-positive and Gram-negative bacteria. Varnishing catheters with AgNPs may help to prevent bacterial colonisation and infections.

An Amphiphilic Carbonaceous/Nanosilver Composite-Incorporated Urinary Catheter for Long-Term Combating Bacteria and Biofilms

Biofilms formed on urinary catheters remain a major headache in the modern healthcare system. Among the various kinds of biocide-releasing urinary catheters that have been developed to prevent biofilm formation, Ag nanoparticles (AgNPs)-coated catheters are of great promising potential. However, the deposition of AgNPs on the surface of catheters suffers from several inherent shortcomings, such as damage to the urethral mucosa, uncontrollable Ag ion kinetics, and unexpected systematic toxicity. Here, AgNPs-decorated amphiphilic carbonaceous particles (ACPs@AgNPs) with commendable dispersity in solvents of different polarities and broad-spectrum antibacterial activity are first prepared. The resulting ACPs@AgNPs exert good compatibility with silicone rubber, which enables the easy fabrication of urinary catheters using a laboratory-made mold. Therefore, ACPs@AgNPs not only endow the urinary catheter with forceful biocidal activity but also improve its mechanical properties and surface wettability. Hence, the designed urinary catheter possesses excellent capacity to resist bacterial adhesion and biofilm formation both in vitro and in an in vivo rabbit model. Specifically, a long-term antibacterial study highlights its sustainable antibacterial activity. Of note, no obvious toxicity or inflammation in rabbits was triggered by the designed urinary catheter in vivo. Overall, the hybrid urinary catheter may serve as a promising biocide-releasing urinary catheter for antibacterial and antibiofilm applications.

Use of Pistacia lentiscus mastic for sustained-release system of chlorocresol and benzoic acid for in vitro prevention of bacterial colonization of silicon urinary catheter

Urinary tract infections (UTI) are among the most common types of nosocomial infections. Patients with indwelling urinary catheters are at the highest risk of getting infections. A sustained-release method of chlorocresol and benzoic acid using a varnish of Pistacia lentiscus mastic was developed to prevent catheter colonization by Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis and Pseudomonas aeruginosa. Coatings of both antiseptics significantly reduced the number of colonizing bacteria on silicon urinary catheters for 72 h. Chlorocresol-coated catheters were significantly (P ≤ 0·05) more effective than benzoic acid. Except for the Pr. mirabilis, chlorocresol completely inhibited the colonization of catheters by the tested bacteria for 48 h. Nonetheless, the colonization of catheters by Pr. mirabilis was significantly reduced after 48 and 72 h by more than 3·5 logs. Although benzoic acid failed to completely inhibit bacterial growth, it significantly reduced the colonization of the catheters by all the tested bacteria by more than two logs for 72 h. The inhibition of colonization of catheters was confirmed by examining the tested catheters by scanning electron microscopy. The obtained results indicate the potential benefits of using mastic as a varnish for sustaining the release of chlorocresol and benzoic acid to prevent and reduce the colonization of urinary catheters by bacteria.

In vivo catheterization study of chlorhexidine-loaded nanoparticle coated Foley urinary catheters in male New Zealand white rabbits

Foley urinary catheters were coated with chlorhexidine-loaded nanoparticles (CHX-NPs), encapsulated in the form of micelles and nanospheres. Both of nanoparticles were deposited by multilayer nanocoating through dip and spray coating on the catheter surface both inner and outer surface. In our previous studies, the nanocoating of Foley urinary catheters was studied for chlorhexidine release, degradation, antibacterial evaluation, cytotoxicity assessment, hemocompatibility, skin irritation, skin sensitization, and stability during storage. The results demonstrated the antimicrobial functions and biocompatibility of the coated catheters. In this study, coated urinary catheters were inserted in the bladders of rabbits for 7 day to investigate their efficacy. Histopathology results showed no inflammation, redness, or swelling on bladder and urethra tissues. Surface morphology comparison of uncoated catheters in the control group and coated catheters in the treatment group revealed more encrustation and crystallization on uncoated catheter than on coated catheter, indicating that catheters coated with CHX-NPs showed efficacy in delaying encrustation and bacterial colonization. These findings suggest that nanocoating of urinary catheters can potentially enhance the biocompatibility of medical devices.

ANTIMICROBIAL AGENTS AND ANTI-ADHESION MATERIALS FOR MEDICAL AND SURGICAL GLOVES

Healthcare-associated infections (HAIs) can be common in healthcare settings, such as the intensive care unit and surgical sites, if proper precautions are not followed. Although traditional techniques are encouraged, such as educating the public and healthcare workers to practice proper handwashing or to double glove, they have not been fully effective in combating HAIs. The use of surface-modified antimicrobial gloves may be an alternative approach to prevent the transmission of pathogens between healthcare workers and patients. This paper gives a comprehensive review of strategies to produce antimicrobial gloves. The chemistry of some potential chemically synthesized antimicrobial agents and nature-inspired superhydrophobic surfaces are discussed. The principles of killing microbes must be understood to effectively select these materials and to design and fabricate surfaces for the reduction of bacterial adhesion. Also, current company trends and technologies are presented for gloves proven to effectively kill bacteria. Such glove use, when coupled with in-depth research on diverse surgical procedures and medical examinations, could ease the burden of HAIs.

Inhibition of bacterial adherence to biomaterials by coating antimicrobial peptides with anionic surfactant

Medical devices are widely used in modern medicine, but their utilities are often limited by the biofilm formation of bacteria that are tolerant to most antibiotics. In this report, antimicrobial peptides (AMPs) were coated onto biomaterials by the aid of surfactant through hydrophobic interactions. To increase the coating efficiency, stability of AMPs in body fluids and spectrum of antimicrobial activity, pairs of AMPs were coated simultaneously onto various substrates, such as silicone, polyurethane and titanium, which are commonly used components of biomedical devices. These coated AMPs exhibited very low cytotoxicity and hemolytic activities because they were gradually released into urine or serum. The AMP pairs, such as T9W + SAAP159 and T9W + RRIKA, coated onto the silicone discs were able to inhibit in vitro bacterial adherence in urine. Most importantly, AMP pairs coated onto the silicone tubing by surfactant SDBS could prevent bacterial adherence to mouse bladder and the silicone tubing implanted within it. These results provide a promising approach towards circumventing urinary catheter-associated infections caused by bacterial adherence.

Histological and morphometric evaluation of the urethra and penis in male New Zealand White rabbits

This stereudy aimed at performing a histological and morphometric evaluation of the urethra and penis of male rabbits. Seven male New Zealand White rabbits weighing 2.1-3 kg were used in the study. The whole urethra, from the urinary bladder to the external urethral orifice, was dissected from the rabbits, and the tissue was sliced into sections at an interval of 2 mm. The sections were stained with haematoxylin-eosin, Masson-Goldner trichrome stain, Van Gieson's stain and Movat-Russell modified pentachrome stain. A detailed evaluation of the morphology and morphometry was performed. The parameters assessed were the type and height of epithelium, thickness and composition of connective tissue, and thickness and structure of muscularis. The histological structure of the rabbit urethra was found to be similar to humans. However, although the rabbits were found to have the same type of penis as the humans, the internal structure of the corpora cavernosa, the relative thickness of the tunica albuginea and the rudimentary glands of the penis were found to differ in these animals. The results of the present study may be useful in the designing of implants, drug testing or surgical procedures on the physiological and pathological urethra.

Development of dual anti-biofilm and anti-bacterial medical devices

Silicone catheters impregnated with antibiotics and coated with an anti-attachment polyacrylate produce a device with dual anti-biofilm and anti-bacterial properties.

Evaluating Efficacy of Antimicrobial and Antifouling Materials for Urinary Tract Medical Devices: Challenges and Recommendations

In Europe, the mean incidence of urinary tract infections in intensive care units is 1.1 per 1000 patient-days. Of these cases, catheter-associated urinary tract infections (CAUTI) account for 98%. In total, CAUTI in hospitals is estimated to give additional health-care costs of £1-2.5 billion in the United Kingdom alone. This is in sharp contrast to the low cost of urinary catheters and emphasizes the need for innovative products that reduce the incidence rate of CAUTI. Ureteral stents and other urinary-tract devices suffer similar problems. Antimicrobial strategies are being developed, however, the evaluation of their efficacy is very challenging. This review aims to provide considerations and recommendations covering all relevant aspects of antimicrobial material testing, including surface characterization, biocompatibility, cytotoxicity, in vitro and in vivo tests, microbial strain selection, and hydrodynamic conditions, all in the perspective of complying to the complex pathology of device-associated urinary tract infection. The recommendations should be on the basis of standard assays to be developed which would enable comparisons of results obtained in different research labs both in industry and in academia, as well as provide industry and academia with tools to assess the antimicrobial properties for urinary tract devices in a reliable way.

On-demand release of Candida albicans biofilms from urinary catheters by mechanical surface deformation

Candida albicans is a leading cause of catheter-associated urinary tract infections and elimination of these biofilm-based infections without antifungal agents would constitute a significant medical advance. A novel urinary catheter prototype that utilizes on-demand surface deformation is effective at eliminating bacterial biofilms and here the broader applicability of this prototype to remove fungal biofilms has been demonstrated. C. albicans biofilms were debonded from prototypes by selectively inflating four additional intralumens surrounding the main lumen of the catheters to provide the necessary surface strain to remove the adhered biofilm. Deformable catheters eliminated significantly more biofilm than the controls (>90% eliminated vs 10% control; p < 0.001). Mechanical testing revealed that fungal biofilms have an elastic modulus of 45 ± 6.7 kPa with a fracture energy of 0.4-2 J m^-2. This study underscores the potential of mechanical disruption as a materials design strategy to combat fungal device-associated infections.

Evaluation of a ureteral catheter coating by means of a BioEncrustation in vitro model

Biomaterials for applications in the urinary tract are challenged with both biofilm formation and encrustation, two highly interconnected processes. While great effort has been achieved developing promising materials there is only a limited choice of sophisticated in vitro models that are available to analyse the performance of biomaterials prior to performing delicate and expensive in vivo studies. In this study we present a complex BioEncrustation model that imitates both the processes of multi-species biofilm formation and encrustation in vitro. The resulting crystalline biofilms are compared to the deposits found on explanted ureteral stent surfaces (in vivo situation) and to deposits formed in an experimental set up that does not contain bacteria (Encrustator®). Further focus of this study is dedicated to employing the developed BioEncrustation model to evaluate the effect multifunctional coatings impose on the processes of biofilm formation and encrustation under in vitro conditions. The investigated TANP coating combines unspecific and broad band specific antibacterial properties with a degrading polymer matrix that is intended to inhibit crystal formation. The coating was prepared on both polyurethane and silicone tubes and the subsequent results of the in vitro BioEncrustation analyses reveal a promising potential for employing the coating to render ureteral stent surfaces more biocompatible.

In Vivo Anti-Biofilm and Anti-Bacterial Non-Leachable Coating Thermally Polymerized on Cylindrical Catheter

Catheters are indispensable tools of modern medicine, but catheter-associated infection is a significant clinical problem, even when stringent sterile protocols are observed. When the bacteria colonize catheter surfaces, they tend to form biofilms making them hard to treat with conventional antibiotics. Hence, there is a great need for inherently antifouling and antibacterial catheters that prevent bacterial colonization. This paper reports the preparation of nonleachable antibiofilm and antibacterial cationic film coatings directly polymerized from actual tubular silicone catheter surfaces via the technique of supplemental activator and reducing agent surface-initiated atom-transfer radical polymerization (SARA SI-ATRP). Three cross-linked cationic coatings containing (3-acrylamidopropyl) trimethylammonium chloride (AMPTMA) or quaternized polyethylenimine methacrylate (Q-PEI-MA) together with a cross-linker (polyethylene glycol dimethacrylate, PEGDMA) were tested. The in vivo antibacterial and antibiofilm effect of these nonleachable covalently linked coatings (using a mouse catheter model) can be tuned to achieve 1.95 log (98.88%) reduction and 1.26 log (94.51%) reduction of clinically relevant pathogenic bacteria (specifically with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecalis (VRE)). Our good in vivo bactericidal killing results using the murine catheter-associated urinary tract infection (CAUTI) model show that SARA SI-ATRP grafting-from technique is a viable technique for making nonleachable antibiofilm coating even on "small" (0.30/0.64 mm inner/outer diameter) catheter.

Azithromycin-Ciprofloxacin-Impregnated Urinary Catheters Avert Bacterial Colonization, Biofilm Formation, and Inflammation in a Murine Model of Foreign-Body-Associated Urinary Tract Infections Caused by Pseudomonas aeruginosa

Pseudomonas aeruginosa is a multifaceted pathogen causing a variety of biofilm-mediated infections, including catheter-associated urinary tract infections (CAUTIs). The high prevalence of CAUTIs in hospitals, their clinical manifestations, such as urethritis, cystitis, pyelonephritis, meningitis, urosepsis, and death, and the associated economic challenges underscore the need for management of these infections. Biomaterial modification of urinary catheters with two drugs seems an interesting approach to combat CAUTIs by inhibiting biofilm. Previously, we demonstrated the in vitro efficacy of urinary catheters impregnated with azithromycin (AZM) and ciprofloxacin (CIP) against P. aeruginosa Here, we report how these coated catheters impact the course of CAUTI induced by P. aeruginosa in a murine model. CAUTI was established in female LACA mice with uncoated or AZM-CIP-coated silicone implants in the bladder, followed by transurethral inoculation of 10⁸ CFU/ml of biofilm cells of P. aeruginosa PAO1. AZM-CIP-coated implants (i) prevented biofilm formation on the implant's surface (P ≤ 0.01), (ii) restricted bacterial colonization in the bladder and kidney (P < 0.0001), (iii) averted bacteriuria (P < 0.0001), and (iv) exhibited no major histopathological changes for 28 days in comparison to uncoated implants, which showed persistent CAUTI. Antibiotic implants also overcame implant-mediated inflammation, as characterized by trivial levels of inflammatory markers such as malondialdehyde (P < 0.001), myeloperoxidase (P < 0.05), reactive oxygen species (P ≤ 0.001), and reactive nitrogen intermediates (P < 0.01) in comparison to those in uncoated implants. Further, AZM-CIP-coated implants showed immunomodulation by manipulating the release of inflammatory cytokines interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and IL-10 to the benefit of the host. Overall, the study demonstrates long-term in vivo effectiveness of AZM-CIP-impregnated catheters, which may possibly be a key to success in preventing CAUTIs.

Antifungal activity of a β-peptide in synthetic urine media: Toward materials-based approaches to reducing catheter-associated urinary tract fungal infections

Catheter-associated urinary tract infections (CAUTI) are the most common type of hospital-acquired infection, with more than 30 million catheters placed annually in the US and a 10-30% incidence of infection. Candida albicans forms fungal biofilms on the surfaces of urinary catheters and is the leading cause of fungal urinary tract infections. As a step toward new strategies that could prevent or reduce the occurrence of C. albicans-based CAUTI, we investigated the ability of antifungal β-peptide-based mimetics of antimicrobial peptides (AMPs) to kill C. albicans and prevent biofilm formation in synthetic urine. Many α-peptide-based AMPs exhibit antifungal activities, but are unstable in high ionic strength media and are easily degraded by proteases-features that limit their use in urinary catheter applications. Here, we demonstrate that β-peptides designed to mimic the amphiphilic helical structures of AMPs retain 100% of their structural stability and exhibit antifungal and anti-biofilm activity against C. albicans in a synthetic medium that mimics the composition of urine. We demonstrate further that these agents can be loaded into and released from polymer-based multilayer coatings applied to polyurethane, polyethylene, and silicone tubing commonly used as urinary catheters. Our results reveal catheters coated with β-peptide-loaded multilayers to kill planktonic fungal cells for up to 21days of intermittent challenges with C. albicans and prevent biofilm formation on catheter walls for at least 48h. These new materials and approaches could lead to advances that reduce the occurrence of fungal CAUTI.

STATEMENT OF SIGNIFICANCE

Catheter-associated urinary tract infections are the most common type of hospital-acquired infection. The human pathogen Candida albicans is the leading cause of fungal urinary tract infections, and forms difficult to remove 'biofilms' on the surfaces of urinary catheters. We investigated synthetic β-peptide mimics of natural antimicrobial peptides as an approach to kill C. albicans and prevent biofilm formation in media that mimics the composition of urine. Our results reveal these mimics to retain structural stability and activity against C. albicans in synthetic urine. We also report polymer-based approaches to the local release of these agents within urinary catheter tubes. With further development, these materials-based approaches could lead to advances that reduce the occurrence of fungal urinary tract infections.

Development of X-ray micro-focus computed tomography to image and quantify biofilms in central venous catheter models in vitro

Bacterial infections of central venous catheters (CVCs) cause much morbidity and mortality, and are usually diagnosed by concordant culture of blood and catheter tip. However, studies suggest that culture often fails to detect biofilm bacteria. This study optimizes X-ray micro-focus computed tomography (X-ray µCT) for the quantification and determination of distribution and heterogeneity of biofilms in in vitro CVC model systems.Bacterial culture and scanning electron microscopy (SEM) were used to detect Staphylococcus epidermidis ATCC 35984 biofilms grown on catheters in vitro in both flow and static biofilm models. Alongside this, X-ray µCT techniques were developed in order to detect biofilms inside CVCs. Various contrast agent stains were evaluated using energy-dispersive X-ray spectroscopy (EDS) to further optimize these methods. Catheter material and biofilm were segmented using a semi-automated matlab script and quantified using the Avizo Fire software package. X-ray µCT was capable of distinguishing between the degree of biofilm formation across different segments of a CVC flow model. EDS screening of single- and dual-compound contrast stains identified 10 nm gold and silver nitrate as the optimum contrast agent for X-ray µCT. This optimized method was then demonstrated to be capable of quantifying biofilms in an in vitro static biofilm formation model, with a strong correlation between biofilm detection via SEM and culture. X-ray µCT has good potential as a direct, non-invasive, non-destructive technology to image biofilms in CVCs, as well as other in vivo medical components in which biofilms accumulate in concealed areas.

The Efficacy of Umbelliferone, Arbutin, and N-Acetylcysteine to Prevent Microbial Colonization and Biofilm Development on Urinary Catheter Surface: Results from a Preliminary Study

We evaluated, in a preliminary study, the efficacy of umbelliferone, arbutin, and N-acetylcysteine to inhibit biofilm formation on urinary catheter. We used 20 urinary catheters: 5 catheters were incubated with Enterococcus faecalis (control group); 5 catheters were incubated with E. faecalis in presence of umbelliferone (150 mg), arbutin (60 mg), and N-acetylcysteine (150 mg) (group 1); 5 catheters were incubated with E. faecalis in presence of umbelliferone (150 mg), arbutin (60 mg), and N-acetylcysteine (400 mg) (group 2); and 5 catheters were incubated with E. faecalis in presence of umbelliferone (300 mg), arbutin (60 mg), and N-acetylcysteine (150 mg) (group 3). After 72 hours, planktonic microbial growth and microorganisms on catheter surface were assessed. In the control group, we found a planktonic load of ≥10⁵ CFU/mL in the inoculation medium and retrieved 3.69 × 10⁶ CFU/cm from the sessile cells adherent to the catheter surface. A significantly lower amount in planktonic (p < 0.001) and sessile (p = 0.004) bacterial load was found in group 3, showing <100 CFU/mL and 0.12 × 10⁶ CFU/cm in the incubation medium and on the catheter surface, respectively. In groups 1 and 2, 1.67 × 10⁶ CFU/cm and 1.77 × 10⁶ CFU/cm were found on catheter surface. Our results document that umbelliferone, arbutin, and N-acetylcysteine are able to reduce E. faecalis biofilm development on the surface of urinary catheters.

Antimicrobial and antifouling efficacy of urinary catheters impregnated with a combination of macrolide and fluoroquinolone antibiotics against Pseudomonas aeruginosa

The incidence of catheter associated urinary tract infections (CAUTIs) is increasing worldwide. This study was designed to modify a biomaterial by impregnating a silicone urinary catheter with combination of a macrolide, azithromycin (AZM) and a fluoroquinolone, ciprofloxacin (CIP). Drug release profiles showed slow yet continuous release of antibiotics from catheters for one month. In vitro efficacy testing showed that group B catheters [3% (w v(-1)) CIP + 6% (w v(-1)) AZM] outperformed group A catheters [2% (w v(-1)) CIP + 5% (w v(-1)) AZM] by (1) showing larger zones of inhibition (>31 mm) compared to group A (<28 mm) for up to 30 days against Pseudomonas aeruginosa PAO1; (2) killing adhered bacteria in 24 h compared to 24-48 h in group A; (3) showing longer antimicrobial durability for four weeks; and (4) exhibiting a stable real-time shelf life of one year, suggesting that these catheters can be explored in clinical settings, especially in long-term CAUTI.

Investigation of Antibacterial Activity and Biofilm Formation of Silicones Coated With Minocycline-Rifampicin, Silver Nitrate, and Nitrofurantoin for Short-term Utilization in In Vitro Urinary System Models

OBJECTIVE

To analyze antimicrobial activity and biofilm formation on silicones coated with antimicrobial substances in in vivo short-term catheterization simulation using our newly developed in vitro urinary system model and to compare minocycline-rifampin (MR)-, silver nitrate-, and nitrofurantoin (NF)-coated silicone discs.

MATERIALS AND METHODS

Silicone discs were exposed to bacterial urine suspension for 168 hours. The antimicrobial activities were assessed in the medium, and the inhibition zone diameters were measured. The weight of the silicones was measured for biofilm growth assessment before and after the experiment, and confocal microscopy images were taken.

RESULTS

Although the inhibition zone diameters of silver nitrate silicones were larger than those of pure silicone (PS), MR, and NF silicones, biofilm formation could not be prevented (P < .05). MR and NF silicones were superior to PS in terms of antimicrobial efficacy and prevention of biofilm formation (P < .05). In terms of biofilm prevention, no differences were detected between NF and MR silicones apart from a slightly superior ability of MR silicones to inhibit Escherichia coli (P > .05). Biofilm formation occurred on all silicone discs.

CONCLUSION

In short-term urinary catheter utilization, antimicrobial efficacy and biofilm formation prevention were superior in coated silicones, regardless of the type of antibiotic used, compared with the control group (PS). As the study was conducted in an in vitro setting, the findings should be substantiated with in vivo studies on the grounds that different results may be obtained in these settings.

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.

Bacterial adherence and biofilm formation on medical implants: a review

Biofilms are a complex group of microbial cells that adhere to the exopolysaccharide matrix present on the surface of medical devices. Biofilm-associated infections in the medical devices pose a serious problem to the public health and adversely affect the function of the device. Medical implants used in oral and orthopedic surgery are fabricated using alloys such as stainless steel and titanium. The biological behavior, such as osseointegration and its antibacterial activity, essentially depends on both the chemical composition and the morphology of the surface of the device. Surface treatment of medical implants by various physical and chemical techniques are attempted in order to improve their surface properties so as to facilitate bio-integration and prevent bacterial adhesion. The potential source of infection of the surrounding tissue and antimicrobial strategies are from bacteria adherent to or in a biofilm on the implant which should prevent both biofilm formation and tissue colonization. This article provides an overview of bacterial biofilm formation and methods adopted for the inhibition of bacterial adhesion on medical implants.

A novel rat model of catheter-associated urinary tract infection

PURPOSE

The authors aimed to establish a rat model of catheter-associated UTIs using a complete urethral catheter. Bacterial growth in biofilms on urethral catheters was analyzed using standard culture methods to validate this model.

METHODS

A total of 15 rats were divided into the following three groups according to the duration of indwelling catheter placement: a 2-week group (n = 5, group 1), a 4-week group (n = 5, group 2), and a 6-week group (n = 5, group 3). A urethral catheter was inserted with the distal end buried just beneath the urethra, and it was fixed inside of the urethra with a single suture starting at the vagina so that the suture knot was hidden inside of the vagina, preventing the rats from biting it off. A standard culture method was used to analyze bacterial growth in the biofilms.

RESULTS

All 15 urethral catheters were intact at the end of the experiment. Pseudomonas aeruginosa, Escherichia coli, Enterococcus spp., Enterococcus faecalis, and Corynebacterium spp. were identified in the biofilms on the urethral catheters.

CONCLUSION

Our rat UTI model consisting of a complete urinary catheter is feasible. Our study may provide fundamental data for future biofilm studies incorporating molecular techniques, and even clinical studies.

In vivo biocompatibility and in vitro efficacy of antimicrobial gendine-coated central catheters

Antimicrobial peripherally inserted central catheters (PICCs) might reduce the incidence of central line-associated bloodstream infections (CLABSI). We tested the biocompatibility of a novel gendine-coated (combination of chlorhexidine [CHX] and gentian violet [GV]) PICC in a rabbit intravascular model and tested antimicrobial efficacy in comparison with commercially available minocycline/rifampin (M/R)- and CHX-treated PICCs in an in vitro biofilm colonization model. Gendine-coated and uncoated control PICCs were inserted in the jugular veins of rabbits for 4 days. Histopathological analysis was performed at the end of the 4-day period, and circulating levels of CHX and GV in the blood were measured at different time points using liquid chromatography-mass spectrometry. The antimicrobial efficacy of the PICCs was tested following simulated intravascular indwells of 24 h and 1 week against clinical isolates of methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, Enterobacter cloacae, Candida albicans, and Candida glabrata. Rabbits implanted with gendine-coated PICCs exhibited reduced levels of thrombosis and inflammation compared to those of the rabbits with uncoated controls. No GV was detected in blood samples over the entire study period, and trace concentrations of CHX were detected. The gendine-coated PICCs completely prevented the adherence of all pathogens from 24 h to 1 week (P ≤ 0.001), while M/R-treated, CHX-treated, and control PICCs did not. Gendine-coated PICCs were highly effective in preventing biofilm formation of multidrug-resistant pathogenic bacteria and fungi. Gendine-coated PICCs were biocompatible in an intravascular setting. Further, the pharmacokinetic testing established that acute systemic exposures of CHX and GV from the gendine-coated catheters were well within safe levels.

Development of Gendine-Coated Cannula for Continuous Subcutaneous Insulin Infusion for Extended Use

Continuous subcutaneous insulin infusion (CSII) using pumps is a widely used method for insulin therapy in patients with diabetes mellitus. Among the major factors that usually lead to the discontinuation of CSII are CSII set-related issues, including infection at the infusion site. The American Diabetic Association currently recommends rotating sites every 2 to 3 days. This recommendation adds cost and creates inconvenience. Therefore, in order to prevent infections and extend the duration between insertion site changes, we developed a Teflon cannula coated with a combination of gentian violet and chlorhexidine (gendine) and tested its antimicrobial efficacy against different pathogens. The cannulas were coated with gendine on the exterior surface and dried. The efficacy and durability of gendine-coated cannulas were determined against methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, methicillin-susceptible S. aureus, Streptococcus pyogenes, vancomycin-resistant enterococci, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, and Candida glabrata using a biofilm colonization method. The cytotoxicity of gendine was assessed against mouse fibroblast cell lines. The gendine-coated cannulas showed complete prevention of biofilm colonization of all organisms tested for up to 2 weeks (P < 0.0001) compared to that with the uncoated control. A gendine-coated catheter against mouse fibroblast cells was shown to be noncytotoxic. Our in vitro results show that a novel gendine cannula is highly effective in completely inhibiting the biofilm of multidrug-resistant pathogens for up to 2 weeks and may have potential clinical applications, such as prolonged use, cost reduction, and lower infection rate.

S-Nitroso-N-acetylpenicillamine (SNAP) Impregnated Silicone Foley Catheters: A Potential Biomaterial/Device To Prevent Catheter-Associated Urinary Tract Infections

Urinary Foley catheters are utilized for management of hospitalized patients and are associated with high rates of urinary tract infections (UTIs). Nitric oxide (NO) potently inhibits microbial biofilm formation, which is the primary cause of catheter associated UTIs (CAUTIs). Herein, commercial silicone Foley catheters are impregnated via a solvent swelling method with S-nitroso-N-acetyl-D-penicillamine (SNAP), a synthetic NO donor that exhibits long-term NO release and stability when incorporated into low water-uptake polymers. The proposed catheters generate NO surface-fluxes >0.7 × 10^–10 mol min^–1 cm^–2 for over one month under physiological conditions, with minimal SNAP leaching. These biomedical devices are demonstrated to significantly decrease formation of biofilm on the surface of the catheter tubings over 3, 7, and 14 day periods by microbial species (Staphylococcus epidermidis and Proteus mirabilis) commonly causing CAUTIs. Toxicity assessment demonstrates that the SNAP-impregnated catheters are fully biocompatible, as extracts of the catheter tubings score 0 on a 3-point grading scale using an accepted mouse fibroblast cell-line toxicity model. Consequently, SNAP-impregnated silicone Foley catheters can likely provide an efficient strategy to greatly reduce the occurrence of nosocomial CAUTIs.

Biofilm-related infections: bridging the gap between clinical management and fundamental aspects of recalcitrance toward antibiotics

Surface-associated microbial communities, called biofilms, are present in all environments. Although biofilms play an important positive role in a variety of ecosystems, they also have many negative effects, including biofilm-related infections in medical settings. The ability of pathogenic biofilms to survive in the presence of high concentrations of antibiotics is called "recalcitrance" and is a characteristic property of the biofilm lifestyle, leading to treatment failure and infection recurrence. This review presents our current understanding of the molecular mechanisms of biofilm recalcitrance toward antibiotics and describes how recent progress has improved our capacity to design original and efficient strategies to prevent or eradicate biofilm-related infections.

Bacteriophage-mediated control of a two-species biofilm formed by microorganisms causing catheter-associated urinary tract infections in an in vitro urinary catheter model

Microorganisms from a patient or their environment may colonize indwelling urinary catheters, forming biofilm communities on catheter surfaces and increasing patient morbidity and mortality. This study investigated the effect of pretreating hydrogel-coated silicone catheters with mixtures of Pseudomonas aeruginosa and Proteus mirabilis bacteriophages on the development of single- and two-species biofilms in a multiday continuous-flow in vitro model using artificial urine. Novel phages were purified from sewage, characterized, and screened for their abilities to reduce biofilm development by clinical isolates of their respective hosts. Our screening data showed that artificial urine medium (AUM) is a valid substitute for human urine for the purpose of evaluating uropathogen biofilm control by these bacteriophages. Defined phage cocktails targeting P. aeruginosa and P. mirabilis were designed based on the biofilm inhibition screens. Hydrogel-coated catheters were pretreated with one or both cocktails and challenged with approximately 1×10(3) CFU/ml of the corresponding pathogen(s). The biofilm growth on the catheter surfaces in AUM was monitored over 72 to 96 h. Phage pretreatment reduced P. aeruginosa biofilm counts by 4 log10 CFU/cm2 (P≤0.01) and P. mirabilis biofilm counts by >2 log10 CFU/cm2 (P≤0.01) over 48 h. The presence of P. mirabilis was always associated with an increase in lumen pH from 7.5 to 9.5 and with eventual blockage of the reactor lines. The results of this study suggest that pretreatment of a hydrogel urinary catheter with a phage cocktail can significantly reduce mixed-species biofilm formation by clinically relevant bacteria.

Biofilms on indwelling urologic devices: microbes and antimicrobial management prospect

BACKGROUND

Biofilms (BFs) are a potential source of highly resistant infections, frequently formed on devicesand pose problems for management.

AIM

This study was to develop rational approach for prevention of indwelling urologic device associated biofilm colonization.

SUBJECTS AND METHODS

From randomly selected patients visiting Department of Urology of a tertiary hospital in India 150 uro catheters and 31 used ureteric stents, in-situ for > 30, were collected aseptically. The organisms were isolated and identified from washed devices dipped in broth. Evidence of bacteriuria in each case was checked by semi-quantitative method of urine culture, on day 0 and 14 of device use. The BF statuses of the device-adhered organisms were confirmed by modified method of Christensen. The antibiotic susceptibility was determined by disc diffusion method. Data were analyzed using the Graphpad Prism version 5 statistical software.

RESULTS

Both single and multi-species BFs were formed on catheters, whereas mono-bacterial BFs were exclusive on stents. Predominant organisms were Pseudomonas aeruginosa (30.67%,69/225,) followed by Staphylococcus aureus (15.11%, 34/225), Escherichia coli (13.78%, 31/225), Klebsiella pneumoniae (12%, 27/225), Staphylococcus epidermidis (8.44%, 19/225). Of all strains, (89.33%, 201/225) were found to be BF positive and their colonizations were early indicated by the presence of insignificant bacteriuria in follow-up urine samples. All BF isolates were resistant to at least three antibiotics.

CONCLUSIONS

BF colonization was almost inevitable in prolonged used urinary devices and the most frequent organisms were Pseudomonas, Staphylococcus, and Escherichia spp. Their colonizations usually were indicated by insignificant bacteriuria from follow-up samples. Such BF dislodged organisms were multidrug resistant and could be a source of disseminated infection, yet were in-vitro preventable by many drugs.

Ureteral Stents and Foley Catheters-Associated Urinary Tract Infections: The Role of Coatings and Materials in Infection Prevention

Urinary tract infections affect many patients, especially those who are admitted to hospital and receive a bladder catheter for drainage. Catheter associated urinary tract infections are some of the most common hospital infections and cost the health care system billions of dollars. Early removal is one of the mainstays of prevention as 100% of catheters become colonized. Patients with ureteral stents are also affected by infection and antibiotic therapy alone may not be the answer. We will review the current evidence on how to prevent infections of urinary biomaterials by using different coatings, new materials, and drug eluting technologies to decrease infection rates of ureteral stents and catheters.

Disposable gendine antimicrobial gloves for preventing transmission of pathogens in health care settings

BACKGROUND

Transmission of organisms by contact of gloves with surfaces following contact with a pathogen source has been recognized as an important vector for pathogenesis of health care-associated infections. In these cases, the gloves protect the wearer from contact with the pathogenic organisms; however, this personal protection can facilitate the wearer unwittingly becoming a carrier of the pathogens from one location to another. A novel gendine (combination of chlorhexidine and gentian violet) antiseptic coating for the external surface of the glove was developed as a potential intervention to prevent this mode of transmission.

METHODS

We characterized the ability of the coating to rapidly kill bacterial and fungal pathogens within 1 minute of contact with the glove surface. The International Organization of Standardization 22196 concentrated inoculum contact testing methodology was followed.

RESULTS

The gendine-coated gloves were able to fully eradicate multidrug-resistant organisms included methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterocci, multidrug-resistant Pseudomonas aeruginosa, and Klebsiella pneumoniae carbapenemase producing. In addition, Candida albicans, Candida glabarata, and 2 pathogenic Escherichia coli strains commonly associated with invasive gastroenteritis were also fully eradicated within 1 minute of contact. The gendine coating did not adversely impact the finish or integrity of the disposable gloves.

CONCLUSION

The highly efficacious gendine-coated antimicrobial gloves potentially provide an additional means of protection against horizontal transmission of common pathogens in a hospital setting.

Gentian violet: a 19th century drug re-emerges in the 21st century

Gentian violet (GV) has a long and varied history as a medicinal agent. Historically used as an antibacterial and antifungal, recent reports have shown its utility as an antitypranosomal, antiviral and anti-angiogenic agent. The objective of this article is to summarize evidence regarding the efficacy and safety of GV use in dermatology. Recent discoveries have found novel targets of GV, namely NADPH oxidase in mammalian cells and thioredoxin reductase 2 in bacterial, fungal and parasitic cells. These discoveries have expanded the use of GV in the 21st century. Given that GV is well tolerated, effective and inexpensive, its use in dermatology is predicted to increase.

Solidago, orthosiphon, birch and cranberry extracts can decrease microbial colonization and biofilm development in indwelling urinary catheter: a microbiologic and ultrastructural pilot study

PURPOSE

Plants extracts are used in urology to manage urinary tract infections. We aimed to evaluate the efficacy of a preparation with solidago, orthosiphon, birch and cranberry extracts (CISTIMEV PLUS(®)) in reducing microbial colonization and biofilm development in patients with indwelling urinary catheters.

METHODS

All consecutive outpatients attending our department between January and June 2010 for the substitution of indwelling catheters were considered for this single-blinded, randomized and controlled pilot study to test superiority of the preventative management (CISTIMEV PLUS(®), 1 tablet daily for 30 days) in respect to no treatment. A sample size of 10-40 participants per group was considered adequate. All patients underwent urine culture the same day of the catheter substitution and were then randomized into test group (n = 48) and control group (n = 35). Ultrastructural analysis was also performed. After 30 days, the catheter was replaced and the analysis repeated. The primary outcome was the rate of positive urinary culture at the end of the entire study period.

RESULTS

Ten patients abandoned the study. At 30 days, according to per-protocol analysis, the groups statistically differed regarding the rate of positive urine cultures: test group 10/43 and control group 16/30 (p = 0.013) (-30.1 % [95 % CI -51.94 to -8.21]). The most common isolated bacteria were Escherichia coli and Enterococcus faecalis.

CONCLUSIONS

The use of solidago, orthosiphon, birch and cranberry extracts resulted in a significant reduction of microbial colonization in patients with indwelling urinary catheters. Larger clinical trials are needed to demonstrate that the effects here reported are sufficient to reduce symptomatic catheter-associated urinary tract infections.

A scoping review of important urinary catheter induced complications

This study presents a scoping review of the literature on the morbidity and mortality associated with several common complications of urinary catheterization. Data gathered from the open literature were analyzed graphically to gain insights into the most important urinary catheter induced complications. The results reveal that the most significant catheter complications are severe mechanical trauma (perforation, partial urethral damage and urinary leakage), symptomatic bacterial infection, and anaphylaxis, catheter toxicity and hypersensitivity. The data analysis also revealed that the complications with the highest morbidity are all closely related to the mechanical interaction of the catheter with the urethra. This suggests that there is a strong need for urinary catheter design to be improved to minimize mechanical interaction, especially mechanical damage to the urinary tract, and to enhance patient comfort. Several urinary catheter design directions have been proposed based on tribological principles. Among the key recommendations is that catheter manufacturers develop catheter coatings which are both hydrophilic and antibacterial, and which maintain their antibacterial patency for at least 90 days.

From in vitro to in vivo Models of Bacterial Biofilm-Related Infections

The influence of microorganisms growing as sessile communities in a large number of human infections has been extensively studied and recognized for 30–40 years, therefore warranting intense scientific and medical research. Nonetheless, mimicking the biofilm-life style of bacteria and biofilm-related infections has been an arduous task. Models used to study biofilms range from simple in vitro to complex in vivo models of tissues or device-related infections. These different models have progressively contributed to the current knowledge of biofilm physiology within the host context. While far from a complete understanding of the multiple elements controlling the dynamic interactions between the host and biofilms, we are nowadays witnessing the emergence of promising preventive or curative strategies to fight biofilm-related infections. This review undertakes a comprehensive analysis of the literature from a historic perspective commenting on the contribution of the different models and discussing future venues and new approaches that can be merged with more traditional techniques in order to model biofilm-infections and efficiently fight them.

Bacterial flagella explore microscale hummocks and hollows to increase adhesion

Biofilms, surface-bound communities of microbes, are economically and medically important due to their pathogenic and obstructive properties. Among the numerous strategies to prevent bacterial adhesion and subsequent biofilm formation, surface topography was recently proposed as a highly nonspecific method that does not rely on small-molecule antibacterial compounds, which promote resistance. Here, we provide a detailed investigation of how the introduction of submicrometer crevices to a surface affects attachment of Escherichia coli. These crevices reduce substrate surface area available to the cell body but increase overall surface area. We have found that, during the first 2 h, adhesion to topographic surfaces is significantly reduced compared with flat controls, but this behavior abruptly reverses to significantly increased adhesion at longer exposures. We show that this reversal coincides with bacterially induced wetting transitions and that flagellar filaments aid in adhesion to these wetted topographic surfaces. We demonstrate that flagella are able to reach into crevices, access additional surface area, and produce a dense, fibrous network. Mutants lacking flagella show comparatively reduced adhesion. By varying substrate crevice sizes, we determine the conditions under which having flagella is most advantageous for adhesion. These findings strongly indicate that, in addition to their role in swimming motility, flagella are involved in attachment and can furthermore act as structural elements, enabling bacteria to overcome unfavorable surface topographies. This work contributes insights for the future design of antifouling surfaces and for improved understanding of bacterial behavior in native, structured environments.

Shining light on materials--a self-sterilising revolution

This review focuses on the development of light activated antimicrobial surfaces. These surfaces kill microbes by the action of light and have potential applications in domestic and healthcare settings. The inspiration for the new self-cleaning surfaces originates from photodynamic therapy where light is used to locate and destroy tumours. The first generation photosensitiser molecules, based on a porphyrin ring structure, could be considered as bioinspired and chemically related to chlorophyll. The review looks at developments of both soft polymeric surfaces with either surface bound or impregnated photosensitiser molecules; and hard inorganic surfaces such as modified titanium dioxide. The bacterial kill mechanisms are looked into with both surface types showing primary microbial kill through a radical induced pathway. The hard inorganic surfaces also show low bacterial adherence by means of a light activated photo-wetting of the surfaces meaning that they are "Easy Clean" and wash off microbes uniformly.

Urinary catheterization of male rabbits: a new technique and a review of urogenital anatomy

Rabbits are widely used as an animal model for urologic research studies in which urinary bladder catheterization is required. However, standard manual retrograde urinary catheterization proved to be difficult to perform on anesthetized male rabbits in a research study, with frequent misplacement of the catheter into the vesicular gland. Attempts to reposition the catheter into the bladder after initial entry into the vesicular gland frequently failed and resulted in exclusion of the animal from the study. We assessed the normal anatomy of the lower urinary tract of male rabbits to determine the cause of catheterization misdirection into the vesicular gland and to develop a more reliable technique for urinary bladder catheterization. A modified 'digital (finger) pressure' catheterization technique was developed for successful urinary catheterization of male rabbits. Retrospective statistical analysis of 45 rabbits used for urinary catheterization studies showed improvement in the success rate of catheterization by using the digital pressure technique over the standard method of retrograde urinary catheter insertion. In addition, we here review the relevant gross and histologic anatomy of the urogenital tract of male rabbits.

Prevention of initial biofilm formation on ureteral stents using a sustained releasing varnish containing chlorhexidine: in vitro study

BACKGROUND AND PURPOSE

Ureteral stents are being used exceedingly in the field of urology, and with advancements in endourology, this trend is increasing. Bacterial colonization and proliferation on the stent surface may result in urinary tract infections (UTIs) necessitating the administration of antibiotics that, in turn, may lead to the development of antibiotic-resistant bacterial strains. Several studies have shown that sustained release varnish (SRV) combined with antibiotics or antiseptics can prevent the proliferation of bacteria on urethral catheters. This is the first study that evaluates this technique implemented on ureteral stents.

MATERIALS AND METHODS

We evaluated growth inhibition on ureteral stent segments coated with chlorhexidine (CHX) 1% SRV. The tests were conducted using common urinary pathogens: Enterococci, Pseudomonas, and Escherichia coli. Coated stent segments were inserted into bacterial suspensions. Controls included uncoated stent segments and stents coated with placebo SRV (without CHX).

RESULTS

Bacterial growth measured as turbidity and as colony-forming units showed a significant inhibition effect of initial bacteria adhesion to the CHX-SRV coated stent segments compared with the controls (P<0.001). This inhibitory effect was apparent in each of the bacteria tested and was confirmed by inspection of the stent segments under an electron microscope. In a kinetic experiment using CHX 2% SRV, we were able to prolong the growth inhibition effect from 1 week to nearly 2 weeks.

CONCLUSIONS

We believe this technique may play a significant role in reducing ureteral stent-associated UTIs. Further studies are needed before this approach can be implemented in clinical practice.