A randomized clinical trial comparing Nitrofurazone-coated and uncoated urinary catheters in kidney transplant recipients: Results from a pilot study

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

Medical devices such as venous catheters (VCs) and urinary catheters (UCs) are widely used in the hospital setting. However, the implantation of these devices is often accompanied by complications. About 60 to 70% of nosocomial infections (NIs) are linked to biofilms. The main complication is the ability of microorganisms to adhere to surfaces and form biofilms which protect them and help them to persist in the host. Indeed, by crossing the skin barrier, the insertion of VC inevitably allows skin flora or accidental environmental contaminants to access the underlying tissues and cause fatal complications like bloodstream infections (BSIs). In fact, 80,000 central venous catheters-BSIs (CVC-BSIs)-mainly occur in intensive care units (ICUs) with a death rate of 12 to 25%. Similarly, catheter-associated urinary tract infections (CA-UTIs) are the most commonlyhospital-acquired infections (HAIs) worldwide.These infections represent up to 40% of NIs.In this review, we present a summary of biofilm formation steps. We provide an overview of two main and important infections in clinical settings linked to medical devices, namely the catheter-asociated bloodstream infections (CA-BSIs) and catheter-associated urinary tract infections (CA-UTIs), and highlight also the most multidrug resistant bacteria implicated in these infections. Furthermore, we draw attention toseveral useful prevention strategies, and advanced antimicrobial and antifouling approaches developed to reduce bacterial colonization on catheter surfaces and the incidence of the catheter-related infections.

Urinary Catheters: Materials, Coatings, and Recommendations for Selection

Urinary catheters have been used for more than 3000 years, although materials have changed from wood to silver to rubber. Research continues to try and find the optimal catheter materials, which improve safety and quality of life. Advantages when comparing newer catheter materials are not always obvious but catheters coated with a hydrophilic layer may reduce urethral trauma and the incidence of urinary tract infections. However, extrapolation of the data is limited by lack of end-point standardization and heterogenous populations.

Redox Active Zn@MOFs as Spontaneous Reactive Oxygen Species Releasing Antimicrobials

The rapid development of antimicrobial resistance (AMR) among infectious pathogens has become a major threat and challenge in healthcare systems globally. A strategy distinct from minimizing the overuse of antimicrobials involves the development of novel antimicrobials with a mode of action that prevents the development of AMR microbial strains. Reactive oxygen species (ROS) are formed as a natural byproduct of the cellular aerobic metabolism. However, it becomes pathological when ROS is produced at excessive levels. Exploiting this phenomenon, research on redox-active bactericides has been demonstrated to be beneficial. Materials that release ROS via photodynamic, thermodynamic, and photocatalytic interventions have been developed as nanomedicines and are used in various applications. However, these materials require external stimuli for ROS release to be effective as biocides. In this paper, we report novel zinc-based metal organic framework (Zn@MOF) particles that promote the spontaneous release of active ROS species. The synthesized Zn@MOF spontaneously releases superoxide anions and hydrogen peroxide, exhibiting a potent antimicrobial efficacy against various microbes. Zn@MOF-incorporated plastic films and coatings show excellent, long-lasting antimicrobial potency even under continuous microbial challenge and an aging process. These disinfecting surfaces maintain their antimicrobial properties even after 500× surface wipes. Zn@MOF is also biocompatible and safe on the skin, illustrating its broad potential applications in medical technology and consumer care applications.

Novel Antibacterial Agents SAAP-148 and Halicin Combat Gram-Negative Bacteria Colonizing Catheters

The antibiotic management of catheter-related infections (CRIs) often fails owing to the emergence of antimicrobial-resistant strains and/or biofilm/persister apparitions. Thus, we investigated the efficacy of two novel antimicrobial agents, i.e., the synthetic peptide SAAP-148 and the novel antibiotic halicin, against Gram-negative bacteria (GNB) colonizing catheters. The antibacterial, anti-biofilm, and anti-persister activities of both agents were evaluated against Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae strains. The enrolled strains were isolated from catheters and selected based on their resistance to at least three antibiotic classes and biofilm formation potential. Furthermore, the hemolysis and endotoxin neutralization abilities of these agents were explored. The bactericidal activity of both agents was reduced in urine and plasma as compared to buffered saline. In a dose-dependent manner, SAAP-148 and halicin reduced bacterial counts in 24 h preformed biofilms on silicone elastomer discs and eliminated persisters originating from antibiotic-exposed mature 7-day biofilms, with halicin being less effective than SAAP-148. Importantly, SAAP-148 and halicin acted synergistically on E. coli and K. pneumoniae biofilms but not on A. baumannii biofilms. The peptide, but not halicin, decreased the production of IL-12p40 upon exposure to UV-killed bacteria. This preliminary study showed that SAAP-148 and halicin alone/in combination are promising candidates to fight GNB colonizing catheters.

Novel Endpoints in Solid Organ Transplantation: Targeting Patient-reported Outcome Measures

Although solid organ transplantation improves survival and quality of life in many patients with organ failure, treatment complications and side effects can have debilitating consequences for patients. Patient-reported outcome measures (PROMs) capture how patients feel and function, including quality of life, symptoms, and side effects that are assessed directly by patients. Yet, they remain infrequently reported in trials in solid organ transplantation. Barriers to implementing PROMs in trials include uncertainty in selecting appropriate PROMs, concerns about resources limitations, patient burden, and limited evidence to support the psychometric robustness of measures for use in transplant recipients. In recent years, there have been increasing efforts to include patient-reported outcomes that are important to patients in trials to ensure that trials provide patient-centered information for decision-making. This article will provide an overview of PROMs, discuss PROs that are important to solid organ transplant recipients and those that are used in trials in solid organ transplantation, and outline approaches for selecting PROMs for clinical trials.

Detection of microbial biofilms inside the lumen of ureteral stents: two case reports

BACKGROUND

We report large biofilm structures that covered almost the entirety of the lumen and surface of double-J stents in two postrenal transplant patients, with no development of urinary tract infection. Biofilm bacteria of one patient were integrated by coccus in a net structure, whereas overlapping cells of bacilli were present in the other patient. To the best of our knowledge, this is the first time that high-quality images of the architecture of noncrystalline biofilms have been found inside double-J stents from long-term stenting in renal transplant recipients.

CASE PRESENTATION

Two renal transplant recipients, a 34-year-old male and a 39-year-old female of Mexican-Mestizo origin, who underwent a first renal transplant and lost it due to allograft failure, had a second transplant. Two months after the surgical procedure, double-J stents were removed and analyzed using scanning electron microscopy (SEM). None of the patients had an antecedent of UTI, and none developed UTI after urinary device removal. There were no reports of injuries, encrustation, or discomfort caused by these devices.

CONCLUSION

The bacterial biofilm inside the J stent from long-term stenting in renal transplant recipients was mainly concentrated on unique bacteria. Biofilm structures from the outside and inside of stents do not have crystalline phases. Internal biofilms may represent a high number of bacteria in the double-J stent, in the absence of crystals.

Antimicrobial and cytotoxic synergism of biocides and quorum-sensing inhibitors against uropathogenic Escherichiacoli

BACKGROUND

Uropathogenic Escherichia coli (UPEC) are a primary cause of catheter-associated urinary tract infections (CAUTIs), often forming mature recalcitrant biofilms on the catheter surface. Anti-infective catheter coatings containing single biocides have been developed but display limited antimicrobial activity due to the selection of biocide-resistant bacterial populations. Furthermore, biocides often display cytotoxicity at concentrations required to eradicate biofilms, limiting their antiseptic potential. Quorum-sensing inhibitors (QSIs) provide a novel anti-infective approach to disrupt biofilm formation on the catheter surface and help prevent CAUTIs.

AIM

To evaluate the combinatorial impact of biocides and QSIs at bacteriostatic, bactericidal and biofilm eradication concentrations in parallel to assessing cytotoxicity in a bladder smooth muscle (BSM) cell line.

METHODS

Checkerboard assays were performed to determine fractional inhibitory, bactericidal, and biofilm eradication concentrations of test combinations in UPEC and combined cytotoxic effects in BSM cells.

FINDINGS

Synergistic antimicrobial activity was observed between polyhexamethylene biguanide, benzalkonium chloride or silver nitrate in combination with either cinnamaldehyde or furanone-C30 against UPEC biofilms. However, furanone-C30 was cytotoxic at concentrations below those required even for bacteriostatic activity. A dose-dependent cytotoxicity profile was observed for cinnamaldehyde when in combination with BAC, PHMB or silver nitrate. Both PHMB and silver nitrate displayed combined bacteriostatic and bactericidal activity below the half-maximum inhibitory concentration (IC₅₀). Triclosan in combination with both QSIs displayed antagonistic activity in both UPEC and BSM cells.

CONCLUSION

PHMB and silver in combination with cinnamaldehyde display synergistic antimicrobial activity in UPEC at non-cytotoxic concentrations, suggesting potential as anti-infective catheter-coating agents.

Recent Advances in Antimicrobial Coatings and Material Modification Strategies for Preventing Urinary Catheter-Associated Complications

In recent years, we have witnessed prominent improvements in urinary catheter coatings to tackle the commonly occurring catheter-associated urinary tract infection (CAUTI) in catheterized patients. CAUTIs are claimed to be one of the most frequent nosocomial infections that can lead to various complications, from catheter encrustation to severe septicaemia and pyelonephritis. Besides general prevention hygienic strategies, antimicrobial-coated urinary catheters show great potential in the prevention of urinary catheter-associated complications. The aim of this review is to present and evaluate recent updates on the development of antimicrobial urinary catheters in the context of the aetiology of urinary malfunction. Subsequently, we shed some light on future perspectives of utilizing 3D printing and the surrounding regulatory directions.

Catheter-Associated Urinary Infections and Consequences of Using Coated versus Non-Coated Urethral Catheters-Outcomes of a Systematic Review and Meta-Analysis of Randomized Trials

Coated urethral catheters were introduced in clinical practice to reduce the risk of catheter-acquired urinary tract infection (CAUTI). We aimed to systematically review the incidence of CAUTI and adverse effects in randomized clinical trials of patients requiring indwelling bladder catheterization by comparing coated vs. non-coated catheters. This review was performed according to the 2020 PRISMA framework. The incidence of CAUTI and catheter-related adverse events was evaluated using the Cochran−Mantel−Haenszel method with a random-effects model and reported as the risk ratio (RR), 95% CI, and p-values. Significance was set at p < 0.05 and a 95% CI. Twelve studies including 36,783 patients were included for meta-analysis. There was no significant difference in the CAUTI rate between coated and non-coated catheters (RR 0.87 95% CI 0.75−1.00, p = 0.06). Subgroup analysis demonstrated that the risk of CAUTI was significantly lower in the coated group compared with the non-coated group among patients requiring long-term catheterization (>14 days) (RR 0.82 95% CI 0.68−0.99, p = 0.04). There was no difference between the two groups in the incidence of the need for catheter exchange or the incidence of lower urinary tract symptoms after catheter removal. The benefit of coated catheters in reducing CAUTI risk among patients requiring long-term catheterization should be balanced against the increased direct costs to health care systems when compared to non-coated catheters.

Catheter-Associated Urinary Tract Infections: Current Challenges and Future Prospects

Catheter-associated urinary tract infection (CAUTI) is the most common healthcare-associated infection and cause of secondary bloodstream infections. Despite many advances in diagnosis, prevention and treatment, CAUTI remains a severe healthcare burden, and antibiotic resistance rates are alarmingly high. In this review, current CAUTI management paradigms and challenges are discussed, followed by future prospects as they relate to the diagnosis, prevention, and treatment. Clinical and translational evidence will be evaluated, as will key basic science studies that underlie preventive and therapeutic approaches. Novel diagnostic strategies and treatment decision aids under development will decrease the time to diagnosis and improve antibiotic accuracy and stewardship. These include several classes of biomarkers often coupled with artificial intelligence algorithms, cell-free DNA, and others. New preventive strategies including catheter coatings and materials, vaccination, and bacterial interference are being developed and investigated. The antibiotic pipeline remains insufficient, and new strategies for the identification of new classes of antibiotics, and rational design of small molecule inhibitor alternatives, are under development for CAUTI treatment.

Control Release Coating for Urinary Catheters with Enhanced Released Profile for Sustained Antimicrobial Protection

Catheter-associated urinary tract infections (CAUTIs) are common and pose significant costs to healthcare systems. To date, this problem is largely unsolved as commercially available antimicrobial catheters are still lacking in functionality and performance. A prior study by Lim et al. ( Biotechnol. Bioeng. 2018, 115 (8), 2000-2012) reported the development of a novel anhydrous polycaprolactone (PCL) polymer formulation with controlled-release functionality for antimicrobial peptides. In this follow-up study, we developed an improved antimicrobial peptide (AMP)-impregnated poly(ethylene glycol) (PEG)-polycaprolactone (PCL) anhydrous polymer coating for enhanced sustained controlled-release functionality to provide catheters with effective antimicrobial properties. Varying the ratio of PEG and PEG-PCL copolymers resulted in polymers with different morphologies, consequently affecting the AMP release profiles. The optimal coating, formulated with 10% (w/w) PEG-PCL in PCL, achieved a controlled AMP release rate of 31.65 ± 6.85 μg/mL daily for up to 19 days, with a moderate initial burst release. Such profile is desired for antimicrobial coating as the initial burst release acts as a sterilizer to kill the bacteria present in the urinary tract upon insertion, and the subsequent linear release functions as a prophylaxis to deter opportunistic microbial infections. As a proof-of-concept application, our optimized coating was then applied to a commercial silicone catheter for further antibacterial tests. Preliminary results revealed that our coated catheters outperformed commercial silver-based antimicrobial catheters in terms of antimicrobial performance and sustainability, lasting for 4 days. Application of the controlled-release coating also aids in retarding biofilm formation, showing a lower extent of biofilm formation at the end of seven inoculation cycles.

Broad spectrum antimicrobial PDMS-based biomaterial for catheter fabrication

Background

In addition to the widespread use of antibiotics in healthcare settings, the current COVID-19 pandemic has escalated the emergence of antibiotic resistance. Nosocomial infections among hospitalized patients is a leading site for such resistant microbial colonization due to prolonged use of invasive devices and antibiotics in therapies. Invasive medical devices, especially catheters, are prone to infections that could accelerate the development of resistant microbes. Often, catheters - particularly urinary catheters - are prone to high infection rates. Antibiotic-coated catheters can reduce infection rates and although commercially available, are limited in efficacy and choices.

Methods

Herein, a novel and facile method to fabricate PMDS-based biomaterial for the development of antimicrobial eluting catheters is presented. Silicone based organic polymer polydimethylsiloxane (PDMS) was used to prepare a biomaterial containing novel polymeric imidazolium antimicrobial compound.

Results

It was found that the PDMS-based biomaterials could eradicate microbial colonization even after 60 days in culture with continuous microbial challenge, be recycled over multiple uses, stored at room temperature for long-term usage and importantly is biocompatible.

Conclusion

The PDMS-based biomaterial displayed biocidal functionality on microbes of clinical origin, which form major threats in hospital acquired infections.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s40824-021-00235-5.

Association Between the Placement of a Double-J Catheter and the Risk of Urinary Tract Infection in Renal Transplantation Recipients: A Retrospective Cohort Study of 1038 Patients

BACKGROUND

The incidence of urinary complications in transplantation is 2% to 20%, which can be decreased with the use of a double-J catheter. The objective of this study was to determine the association between the use of the catheter and the probability of urinary tract infection (UTI).

METHODS

We studied a retrospective cohort of 1038 patients divided into 2 groups: those treated with vs without a double-J catheter. Perioperative factors related to catheter use were analyzed. Second, whether the use of the catheter was associated with fewer other urinary complications was analyzed.

RESULTS

Of the whole sample, 72 patients were eliminated from the study, and 358 (37%) received a double-J catheter. UTIs occurred in 190 patients (19.6%), of whom a greater proportion received a catheter: 88 of 358 (24.6%) vs 102 of 608 (16.8%) (odds ratio, 1.61; 95% confidence interval, 1.17-2.22; P = .003).

CONCLUSIONS

The placement of a double-J catheter during transplant is associated with a higher proportion of UTIs, increasing their severity and the cost of care, without having a clear effect on other types of urinary complications.

How to Treat Asymptomatic and Symptomatic Urinary Tract Infections in the Kidney Transplant Recipients?

Patients with end-stage renal functions are treated with renal transplantation. After the transplantation, kidney transplant recipients (KTR) are at the risk of urinary tract infection (UTI). UTI in KTR may be symptomatic and asymptomatic. Asymptomatic UTI is the presence of the organisms without any signs and symptoms. There are various ways suggested in the published research papers to deal with UTI in the KTR. The goal of this literature review is to explore how to treat symptomatic and asymptomatic UTI in KTR. A PubMed search was conducted to identify the studies explaining the methods used to deal with UTI in KTR. A total number of 2158 articles were found while searching for regular keywords; however, we found 996 articles with the medical subject heading (Mesh) keywords. After applying the inclusion/ exclusion criteria, 56 articles with the regular keywords search and 29 articles with the Mesh keywords search were selected. These articles included 24 randomized clinical trials, 16 clinical trials, 7 review articles, 5 case reports, 2 controlled clinical trials, 2 observational studies, and 1 cross-sectional study. Our analysis has shown that the early removal of the stent after the transplantation and the use of antibiotics are beneficial in reducing the incidence of symptomatic UTI in the KTR; whereas, treating asymptomatic UTI in KTR has not been proven helpful in reducing the incidence of developing symptomatic UTI later on.

Dibasic Derivatives of Phenylcarbamic Acid as Prospective Antibacterial Agents Interacting with Cytoplasmic Membrane

1-[2-[({[2-/3-(Alkoxy)phenyl]amino}carbonyl)oxy]-3-(dipropylammonio)propyl]pyrrolidinium/azepan- ium oxalates or dichlorides (alkoxy = butoxy to heptyloxy) were recently described as very promising antimycobacterial agents. These compounds were tested in vitro against Staphylococcus aureus ATCC 29213, Enterococcus faecalis ATCC 29212 (reference and control strains), three methicillin-resistant isolates of S. aureus, and three isolates of vancomycin-resistant E. faecalis. 1-[3-(Dipropylammonio)-2-({[3-(pentyloxy-/hexyloxy-/heptyloxy)phenyl]carbamoyl}oxy)propyl]pyrrolidinium dichlorides showed high activity against staphylococci and enterococci comparable with or higher than that of used controls (clinically used antibiotics and antiseptics). The screening of the cytotoxicity of the compounds as well as the used controls was performed using human monocytic leukemia cells. IC50 values of the most effective compounds ranged from ca. 3.5 to 6.3 µM, thus, it can be stated that the antimicrobial effect is closely connected with their cytotoxicity. The antibacterial activity is based on the surface activity of the compounds that are influenced by the length of their alkoxy side chain, the size of the azacyclic system, and hydro-lipophilic properties, as proven by in vitro experiments and chemometric principal component analyses. Synergistic studies showed the increased activity of oxacillin, gentamicin, and vancomycin, which could be explained by the direct activity of the compounds against the bacterial cell wall. All these compounds demonstrate excellent antibiofilm activity, when they inhibit and disrupt the biofilm of S. aureus in concentrations close to minimum inhibitory concentrations against planktonic cells. Expected interactions of the compounds with the cytoplasmic membrane are proven by in vitro crystal violet uptake assays.

Urinary Catheter Coating Modifications: The Race against Catheter-Associated Infections

Urinary catheters are common medical devices, whose main function is to drain the bladder. Although they improve patients’ quality of life, catheter placement predisposes the patient to develop a catheter-associated urinary tract infection (CAUTI). The catheter is used by pathogens as a platform for colonization and biofilm formation, leading to bacteriuria and increasing the risk of developing secondary bloodstream infections. In an effort to prevent microbial colonization, several catheter modifications have been made ranging from introduction of antimicrobial compounds to antifouling coatings. In this review, we discuss the effectiveness of different coatings in preventing catheter colonization in vitro and in vivo, the challenges in fighting CAUTIs, and novel approaches targeting host–catheter–microbe interactions.