Antimicrobial-impregnated catheters for the prevention of catheter-related bloodstream infections

Surveillance of catheter-related bacteremia in VINCat program

BACKGROUND

Catheter-related bacteremia (CRB) is one of the most frequent infections acquired during hospitalization. We summarize the results of CRB surveillance conducted by the Catalan Program of Surveillance of Nosocomial Infections (VINCat) over the past fifteen years.

METHODS

All episodes of hospital-acquired CRB diagnosed in the 55 Catalan hospitals participating in the VINCat program (2008-2023) were recorded. Annual incidence rates per 1000 patient-days were calculated. Analyses were stratified into three relevant five-year periods: 2008-2012, 2013-2017, and 2018-2022. Incidence rate ratios (IRRs) were used to compare infection rates.

RESULTS

During the study period, 10,212 episodes of nosocomial CRB were diagnosed. The global incidence rate was 0.21 episodes per 1000 patient-days (intensive care units (ICUs): 1.13; medical wards: 0.16; surgical wards: 0.15). Gram-positive bacteria caused 68.3% of the episodes. The incidence rate of CRB acquired in ICUs and that of CRB associated with central venous catheters decreased during the study period, while episodes associated with peripheral venous catheters (PVCs) and peripherally-inserted central venous catheters (PICVCs) significantly increased (p<0.001).

CONCLUSIONS

The current study underscores the necessity for interventional programs targeting PVCs, particularly in non-ICU wards.

In Vitro Biological Evaluation of an Alginate-Based Hydrogel Loaded with Rifampicin for Wound Care

We report a biocompatible hydrogel dressing based on sodium alginate-grafted poly(N-vinylcaprolactam) prepared by encapsulation of Rifampicin as an antimicrobial drug and stabilizing the matrix through the repeated freeze-thawing method. The hydrogel structure and polymer-drug compatibility were confirmed by FTIR, and a series of hydrogen-bond-based interactions between alginate and Rifampicin were identified. A concentration of 0.69% Rifampicin was found in the polymeric matrix using HPLC analysis and spectrophotometric UV-Vis methods. The hydrogel's morphology was evaluated by scanning electron microscopy, and various sizes and shapes of pores, ranging from almost spherical geometries to irregular ones, with a smooth surface of the pore walls and high interconnectivity in the presence of the drug, were identified. The hydrogels are bioadhesive, and the adhesion strength increased after Rifampicin was encapsulated into the polymeric matrix, which suggests that these compositions are suitable for wound dressings. Antimicrobial activity against S. aureus and MRSA, with an increased effect in the presence of the drug, was also found in the newly prepared hydrogels. In vitro biological evaluation demonstrated the cytocompatibility of the hydrogels and their ability to stimulate cell multiplication and mutual cell communication. The in vitro scratch assay demonstrated the drug-loaded alginate-grafted poly(N-vinylcaprolactam) hydrogel's ability to stimulate cell migration and wound closure. All of these results suggest that the prepared hydrogels can be used as antimicrobial materials for wound healing and care applications.

Prescription of Rifampicin for Staphylococcus aureus Infections Increased the Incidence of Corynebacterium striatum with Decreased Susceptibility to Rifampicin in a Hungarian Clinical Center

Several reports have suggested a role for Corynebacterium striatum as an opportunistic pathogen. The authors have conducted a retrospective study at the Clinical Center of the University of Szeged, Hungary, between 2012 and 2021 that revealed significantly increased rifampicin resistance in this species. This work aimed to investigate the reasons behind this phenomenon. The data were collected corresponding to the period between 1 January 2012 and 31 December 2021 at the Department of Medical Microbiology, University of Szeged. To characterize the resistance trends, the antibiotic resistance index was calculated for each antibiotic in use. Fourteen strains with different resistance patterns were further analyzed with Fourier-transform infrared spectroscopy using the IR Biotyper^®. The decline in C. striatum sensitivity to rifampicin seen during the COVID-19 pandemic may have been attributable to the use of Rifadin^® to treat concomitant Staphylococcus aureus infections. The fact that the IR Biotyper^® typing method revealed that the rifampicin-resistant C. striatum strains were closely related supports this hypothesis. The IR Biotyper^® infrared spectroscopy proved to be a modern and fast method to support effective antimicrobial stewardship programs.

Machine learning-assisted ensemble analysis for the prediction of urinary tract infection in elderly patients with ovarian cancer after cytoreductive surgery

BACKGROUND

Urinary tract infection (UTI) is a common type of postoperative infection following cytoreductive surgery for ovarian cancer, which severely impacts the prognosis and quality of life of patients.

AIM

To develop a machine learning assistant model for the prevention and control of nosocomial infection.

METHODS

A total of 674 elderly patients with ovarian cancer who were treated at the Department of Gynaecology at Jingzhou Central Hospital between January 31, 2016 and January 31, 2022 and met the inclusion criteria of the study were selected as the research subjects. A retrospective analysis of the postoperative UTI and related factors was performed by reviewing the medical records. Five machine learning-assisted models were developed using two-step estimation methods from the candidate predictive variables. The robustness and clinical applicability of each model were assessed using the receiver operating characteristic curve, decision curve analysis and clinical impact curve.

RESULTS

A total of 12 candidate variables were eventually included in the UTI prediction model. Models constructed using the random forest classifier, support vector machine, extreme gradient boosting, and artificial neural network and decision tree had areas under the receiver operating characteristic curve ranging from 0.776 to 0.925. The random forest classifier model, which incorporated factors such as age, body mass index, catheter, catheter intubation times, blood loss, diabetes and hypoproteinaemia, had the highest predictive accuracy.

CONCLUSION

These findings demonstrate that the machine learning-based prediction model developed using the random forest classifier can be used to identify elderly patients with ovarian cancer who may have postoperative UTI. This can help with treatment decisions and enhance clinical outcomes.

A Glance at Antimicrobial Strategies to Prevent Catheter-Associated Medical Infections

Urinary and intravascular catheters are two of the most used invasive medical devices; however, microbial colonization of catheter surfaces is responsible for most healthcare-associated infections (HAIs). Several antimicrobial-coated catheters are available, but recurrent antibiotic therapy can decrease their potential activity against resistant bacterial strains. The aim of this Review is to question the actual effectiveness of currently used (coated) catheters and describe the progress and promise of alternative antimicrobial coatings. Different strategies have been reviewed with the common goal of preventing biofilm formation on catheters, including release-based approaches using antibiotics, antiseptics, nitric oxide, 5-fluorouracil, and silver as well as contact-killing approaches employing quaternary ammonium compounds, chitosan, antimicrobial peptides, and enzymes. All of these strategies have given proof of antimicrobial efficacy by modifying the physiology of pathogens or disrupting their structural integrity. The aim for synergistic approaches using multitarget processes and the combination of both antifouling and bactericidal properties holds potential for the near future. Despite intensive research in biofilm preventive strategies, laboratorial studies still present some limitations since experimental conditions usually are not the same and also differ from biological conditions encountered when the catheter is inserted in the human body. Consequently, in most cases, the efficacy data obtained from in vitro studies is not properly reflected in the clinical setting. Thus, further well-designed clinical trials and additional cytotoxicity studies are needed to prove the efficacy and safety of the developed antimicrobial strategies in the prevention of biofilm formation at catheter surfaces.

A New Antibiotic-Loaded Sol-Gel can Prevent Bacterial Intravenous Catheter-Related Infections

The aim of this study was to evaluate the effectiveness of a moxifloxacin-loaded organic-inorganic sol-gel (A50) by locally preventing the catheter-related bloodstream infection (CRBSI) provoked by Staphylococcus epidermidis (S. epidermidis) and the effect resulting from its hydrolytic degradation on coagulation by using a rabbit in-vivo model. A50 coating can completely inhibit growth and would locally prevent CRBSI provoked by S. epidermidis. None of the coagulation blood parameters showed a significant difference constant over time between the control catheter group and the A50-coated catheter group, despite the visible silica release resulting from physiological A50 sol-gel degradation detected in serum at least during the first week. At pathological level, foreign body reaction was present in both of types of catheter, and it was characterized by the presence of macrophages and foreign body giant cell. However, this reaction was different in each group: the A50-coated catheter group showed a higher inflammation with histiocytes, which were forming granuloma-like aggregates with an amorphous crystalline material inside, accompanied by other inflammatory cells such as plasma cells, lymphocytes and mast cells. In conclusion, A50 coating a venous catheter showed excellent bactericidal anti-biofilm response since it completely inhibited S. epidermidis biofilm development and, far from showing procoagulant effects, showed slightly anticoagulant effects.

Time-Resolved Dynamics of Struvite Crystallization: Insights from the Macroscopic to Molecular Scale

The crystallization of magnesium ammonium phosphate hexahydrate (struvite) often occurs under conditions of fluid flow, yet the dynamics of struvite growth under these relevant environments has not been previously reported. In this study, we use a microfluidic device to evaluate the anisotropic growth of struvite crystals at variable flow rates and solution supersaturation. We show that bulk crystallization under quiescent conditions yields irreproducible data owing to the propensity of struvite to adopt defects in its crystal lattice, as well as fluctuations in pH that markedly impact crystal growth rates. Studies in microfluidic channels allow for time-resolved analysis of seeded growth along all three principle crystallographic directions and under highly controlled environments. After having first identified flow rates that differentiate diffusion and reaction limited growth regimes, we operated solely in the latter regime to extract the kinetic rates of struvite growth along the [100], [010], and [001] directions. In situ atomic force microscopy was used to obtain molecular level details of surface growth mechanisms. Our findings reveal a classical pathway of crystallization by monomer addition with the expected transition from growth by screw dislocations at low supersaturation to that of two-dimensional layer generation and spreading at high supersaturation. Collectively, these studies present a platform for assessing struvite crystallization under flow conditions and demonstrate how this approach is superior to measurements under quiescent conditions.

The SiLuDrain Trial: a prospective randomized controlled trial comparing standard versus silver-impregnated lumbar drains

OBJECTIVE

Catheter-associated cerebrospinal fluid (CSF) infection remains a serious event, especially for patients in neurocritical care units. The use of external ventricular drain (EVD) catheters impregnated with antimicrobial substances has led to a significant reduction of infection rates. This study was undertaken to compare the use of antimicrobial, silver-impregnated external lumbar drains (si-ELDs) and conventional ELDs.

METHODS

Patients with an indication for ELD placement were randomized to receive either a conventional or an si-ELD catheter. Regular assessment for CSF infections and device-related complications was performed. Neurosurgeons placing the ELD rated the usability and handling of the catheter on a 6-item ordinal performance scale (range: 1, very bad, to 5, very good). All microorganisms isolated in this study were tested for silver-susceptibility via a catheter-roll method.

RESULTS

A total of 48 patients were enrolled in the trial. The si-ELD catheters showed a nonsignificantly lower infection rate compared to conventional ones (4.2% vs 16.7%, p = 0.16). The majority of infections were caused by Staphylococcus species. Device-related complications occurred significantly less often with silver-impregnated-catheters than with conventional ones (8.3% vs 37.5%, p = 0.02). The usability was rated significantly better for si-ELDs (p = 0.003). Antimicrobial susceptibility was shown for si-ELDs against various Staphylococcus spp., but Candida parapsilosis and Escherichia coli were not affected by this antimicrobial agent.

CONCLUSIONS

Silver-impregnated ELD catheters, which could potentially reduce the number of CSF infections, show significantly better properties in regard to handling and fewer device-related complications. Whether they are superior to antibiotic-impregnated catheters or a clinical regimen involving antibiotic prophylaxis remains to be proven.Clinical trial registration no.: DRKS00013513 (Deutsches Register Klinischer Studien).

The efficacy of a non-leaching antibacterial central venous catheter - a prospective, randomized, double-blind study

BACKGROUND

Antimicrobial coatings of central venous catheters (CVC) have the potential to reduce the risk of infectious complications. The aim of this study was to examine the efficacy of a catheter with a non-leaching antimicrobial coating against catheter colonization and bloodstream infections (BSI).

METHODS

The study was conducted in two centers using a prospective, randomized, double-blind and controlled design (680 intensive care patients; a protective CVC (Certofix® protect) or a standard CVC (Certofix®). Primary objectives were the rates of catheter colonization and BSI in the two groups. Other baseline demographics, APACHE II score, insertion site, location of CVC placement (ICU or theatre), indwelling time and length of ICU stay were comparable for both groups.

RESULTS

While the rate of catheter colonization between the coated and uncoated CVC (17.4% vs. 18.7%, P=0.7477) and the rate of microbiologically confirmed catheter associated infections were similar (1.4% vs. 1.9%, P=0.7521), the coated CVC showed a significantly lower incidence of BSI (2.0% vs. 6.5%, P=0.0081) and a significantly lower mean incidence of BSI per 1000 catheter days (3.2 vs. 8.3, P=0.0356).

CONCLUSION

The non-leaching antibacterial coating of the protective catheter was effective in reducing the incidence of BSI but not the rate of catheter colonization. However, the incidence of BSI is a better surrogate marker for the risk of developing clinical signs of infection suggesting that use of the non-leaching protective catheter is effective in this regard. Trial number: ClinicalTrials.gov (ID: NCT00555282), https://clinicaltrials.gov/show/NCT00555282.

The Antimicrobial Efficacy of Hypoxia Mimicking Cobalt Oxide Doped Phosphate-Based Glasses against Clinically Relevant Gram Positive, Gram Negative Bacteria and a Fungal Strain

Bioactive phosphate glasses are of considerable interest for a range of soft and hard tissue engineering applications. The glasses are degradable and can release biologically important ions in a controlled manner. The glasses can also potentially be used as an antimicrobial delivery system. In the given study, novel cobalt-doped phosphate-based glasses, (P₂O₅)₅₀(Na₂O)₂₀(CaO)_30-x(CoO)_x where 0 ≤ x (mol %) ≤ 10, were manufactured and characterized. As the cobalt oxide concentration increased, the rate of dissolution was observed to decrease. The antimicrobial potential of the glasses was studied using direct and indirect contact methods against both Escherichia coli (NCTC 10538) Staphylococcus aureus (ATCC 6538) and Candida albicans (ATCC 76615). The results showed strong, time dependent, and strain specific antimicrobial activity of the glasses against microorganisms when in direct contact. Antimicrobial activity (R) ≥ 2 was observed within 2 h against Escherichia coli, whereas a similar effect was achieved in 6 h against Staphylococcus aureus and Candida albicans. However, when in indirect contact, the dissolution products from the bioactive glasses failed to show an antimicrobial effect. Following direct exposure to the glasses for 7 days, osteoblast-like SAOS-2 cells showed a 5-fold increase in VEGF mRNA while THP-1 monocytic cells showed a 4-fold increase in VEGF mRNA expression when exposed to 10% CoO-doped glass compared with the cobalt free control glass. Endothelial cells stimulated with conditioned medium taken from cell cultures of THP-1 monocytes exposed to 10% CoO doped glass showed clear tubelike structure (blood vessel) formation after 4 h.

Antiseptic measures during the insertion and manipulation of vascular catheters

Several measures related to asepsis for preventing catheter-related bloodstream infection have been proposed. The aseptic measures recommended by scientific societies include hand hygiene of the person who is inserting or manipulating the catheter; maximum sterile barrier precautions during catheter insertion; disinfection of catheter hubs; the use of needle-less connectors and injection ports; the avoidance of antibiotic ointments (except in hemodialysis catheters); change the dressing if it is soiled, loose or damp; and aseptic technique during dressing changes. Other measures only recommended by the most recently published guides (possibly due to the publication of recent studies reporting their beneficial effects) are the use of antimicrobial-impregnated dressings, changing transparent dressings every 7 days, and bathing of the patient with chlorhexidine. This article is part of a supplement entitled "Antisepsis in the critical patient", which is sponsored by Becton Dickinson.

Long-term outcomes of bovine pericardial patch angioplasty for recurrent stenosis in vascular access: A UK single-centre experience

INTRODUCTION:

Stenosis of an arteriovenous fistula or arteriovenous graft for dialysis is a common problem. Stenosis may lead to a number of problems including failure of the fistula. Treatment of stenosis is commonly with percutaneous angioplasty or surgical patch angioplasty with autologous vein or synthetic graft or patch. Here we report the use of bovine pericardial patch angioplasty as an alternative mode of patch angioplasty when percutaneous intervention has failed.

METHODS:

Patients with fistulae treated with bovine patch angioplasty between 2013 and 2016 were identified from a prospectively maintained renal access database (Cyberren^®). Patient records were reviewed, noting type and location of access, patency, re-interventions and complications post bovine pericardial patch.

RESULTS:

A total of 40 patients were identified as having undergone bovine pericardial patch angioplasty between January 2013 and April 2016. The median time from fistula formation to bovine pericardial patch was 15 months (interquartile range (IQR): 5-43). Median duration of follow-up was 14 months (IQR: 5-18). Primary patency at 6, 12, 18 and 24 months was 91%, 66%, 61% and 54%, respectively. Secondary patency was 94%, 91%, 80% and 77% at the same time points, respectively. In total, 15 patients required 23 re-interventions post bovine pericardial patch. There has been no report of infection or aneurysm formation.

CONCLUSION:

Bovine pericardial patch angioplasty for recurrent stenosis in arteriovenous fistulae for dialysis access provides a robust alternative to other surgical patches with the added advantage of allowing early needling and relative resistance to infection. Rates of restenosis and failure post bovine pericardial patch are low.

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.

A review in emergency central venous catheterization

Central venous catheterization is widely used in the emergency setting. This review aims to assess central venous catheterization from the perspectives of types of catheters, sites of insertion, and techniques. In emergency conditions, non-tunneled catheters are preferred because the technique for its insertion is not complicated and less time-consuming. The size of catheter depends on the purpose of catheterization. For example, a large bore catheter is needed for rapid infusion. The ideal catheterization site should bear fewer thromboses, lower infectious rate, and fewer mechanical complications. Thus the femoral vein should be avoided due to a high rate of colonization and thrombosis while the subclavian vein seems to exhibit fewer infectious complications compared with other sites. The ultrasound-guided technique increases the success rate of insertion while decreases the mechanical complications rate.

Biofilm formation in total hip arthroplasty: prevention and treatment

This review assesses the current knowledge on treatments, pathogenesis and the prevention of infections associated with orthopaedic implants, with a focus on total hip arthroplasty.