Reduction of catheter-related colonisation by the use of a silver zeolite-impregnated central vascular catheter in adult critical care

Silver Diamine Fluoride as a Medicament for the Indirect Pulp Therapy in Primary Teeth: A Review of the Literature

Silver diamine fluoride (SDF) has been demonstrated to be effective in arresting caries lesions and, recently, clinical trials have assessed the effectiveness of SDF as a medicament for indirect pulp therapy (IPT) in primary teeth. This review aims to summarize the literature related to the use of SDF and find out if SDF can be used as an effective material for IPT. A literature search was undertaken on electronic databases including PubMed, MEDLINE, ScienceDirect, and Google Scholar, which elicited 50 studies employing different materials in the IPT of primary molars; however, of them, only four clinical trials used SDF as indirect pulp capping (IPC) material. SDF has the potential to be a useful material for IPT in primary teeth. It is a handy choice for pediatric dentists due to its minimum invasiveness, ease of application, and ability to stop the progression of caries. However, more studies are needed to determine whether SDF can be used routinely for IPT and whether it can even replace the currently available materials, as well as to fully realize its potential and establish criteria for its ideal application in IPT procedures.

Thermal susceptibility and antibiotic synergism of methicillin-resistant Staphylococcus aureus biofilms

Methicillin-Resistant Staphylococcus aureus (MRSA) biofilms are among the most dangerous infections on medical implants, typically requiring surgical explantation and replacement. This study investigated the thermal susceptibility of MRSA biofilms to thermal shocks from 60 to 80 °C for 1-30 min as well as the effect of various antibiotics (most notably methicillin) on thermal mitigation. Pre- and post-shock exposure to three different classes of antibiotics (ciprofloxacin, tobramycin, and methicillin) at concentrations ranging from 0.25 to 128 μg mL-1 were investigated. MRSA biofilms exhibited thermal susceptibility comparable to other common nosocomial pathogens, such as Pseudomonas aeruginosa, though with greater variability. Exposure to antibiotics of any class significantly decreased the degree of thermal shock required for reliable mitigation, including at subclinical concentration. These combined treatments reduced biofilm population more than the sum of thermal and chemical treatments alone, demonstrating synergism, while also indicating a critical population drop of ∼4.5 log10 beyond which the biofilms typically became non-viable.

Computer Simulation of the Interaction between SARS-CoV-2 Spike Protein and the Surface of Coinage Metals

A prominent feature of the SARS-CoV-2 virus is the presence of a large glycoprotein spike protruding from the virus envelope. The spike determines the interaction of the virus with the environment and the host. Here, we used an all-atom molecular dynamics simulation method to investigate the interaction of up- and down-conformations of the S1 subunit of the SARS-CoV-2 spike with the (100) surface of Au, Ag, and Cu. Our results revealed that the spike protein is adsorbed onto the surface of these metals, with Cu being the metal with the highest interaction with the spike. In our simulations, we considered the spike protein in both its up-conformation S^up (one receptor binding domain exposed) and down-conformation S^down (no exposed receptor binding domain). We found that the affinity of the metals for the up-conformation was higher than their affinity for the down-conformation. The structural changes in the spike in the up-conformation were also larger than the changes in the down-conformation. Comparing the present results for metals with those obtained in our previous MD simulations of S^up with other materials (cellulose, graphite, and human skin models), we see that Au induces the highest structural change in S^up, larger than those obtained in our previous studies.

Applications of Gold and Silver Nanoparticles in Theranostics

Nanotechnology sculptures the current scenario of science and technology. The word nano refers 'small' which ranges from 10 to 100 nm in size. Silver and gold nanoparticles can be synthesized at nanoscale and have unique biological properties like antibacterial, antifungal, antiviral, antiparasitic, antiplatelet, anti-inflammatory, and anti-tumor activity. In this mini review, we shall discuss the various applications of silver and gold nanoparticles (AuNPs) in the field of therapy, imaging, biomedical devices and in cancer diagnosis. The usage of silver nanoparticles(AgNPs) in dentistry and dental implants, therapeutic abilities like wound dressings, silver impregnated catheters, ventricular drainage catheters, combating orthopedic infections, and osteointegration will be elaborated. Gold nanoparticles in recent years have garnered large importance in bio medical applications. They are being used in diagnosis and have recently seen a surge in therapeutics. In this mini review, we shall see about the various applications of AuNP and AgNP, and highlight their evolution in theranostics.

Thermal Shock and Ciprofloxacin Act Orthogonally on Pseudomonas aeruginosa Biofilms

Bacterial biofilm infections are a major liability of medical implants, due to their resistance to both antibiotics and host immune response. Thermal shock can kill established biofilms, and some evidence suggests antibiotics may enhance this efficacy, despite having an insufficient effect themselves. The nature of this interaction is unclear, however, complicating efforts to integrate thermal shock into implant infection treatment. This study aimed to determine whether these treatments were truly synergistic or simply orthogonal (i.e., independent). Pseudomonas aeruginosa biofilms of different architectures and stationary-phase population density were subjected to various thermal shocks, antibiotic exposures, or combinations thereof, and examined either immediately after treatment or after subsequent reincubation. Population decreases from the combination treatment matched the product of the decreases of individual treatments, indicating their orthogonality. However, reincubation showed binary behavior, where biofilms with an immediate population decrease beyond a critical factor (~104) died off completely during reincubation, while biofilms with a smaller immediate decrease regrew. This critical factor was independent of the initial population density and the combination of treatments that achieved the immediate decrease. While antibiotics do not appear to enhance thermal shock directly, their contribution to achieving a critical population decrease for biofilm elimination can make the treatments appear strongly synergistic, strongly decreasing the intensity of thermal shock needed.

The Impact of Engineered Silver Nanomaterials on the Immune System

Over the last decades there has been a tremendous volume of research efforts focused on engineering silver-based (nano)materials. The interest in silver has been mostly driven by the element capacity to kill pathogenic bacteria. In this context, the main area of application has been medical devices that are at significant risk of becoming colonized by bacteria and subsequently infected. However, silver nanomaterials have been incorporated in a number of other commercial products which may or may not benefit from antibacterial protection. The rapid expansion of such products raises important questions about a possible adverse influence on human health. This review focuses on examining currently available literature and summarizing the current state of knowledge of the impact of silver (nano)materials on the immune system. The review also looks at various surface modification strategies used to generate silver-based nanomaterials and the immunomodulatory potential of these materials. It also highlights the immune response triggered by various silver-coated implantable devices and provides guidance and perspective towards engineering silver nanomaterials for modulating immunological consequences.

Synthesis of Calix-Salen Silver Corates for Evaluation of Their Antimicrobial and Anticancer Activities

Silver-based products are becoming popular as antimicrobial agents because of the failure of antibiotics available for tackling the drug-resistant microbial strains. As silver is well tolerated by normal human cells, silver complexes have emerged as important antineoplastic agents. Further, if silver ions are encapsulated within an organic molecule-an azacorand-it may serve as a better substitute for cisplatin or other metal complexes. The calix-salen-type corates were synthesized using silver ions as the template. 5,5'-methylene-bis-salicylaldehyde was reacted with ethylene diamine in methanol at room temperature in the presence of silver nitrate. The resultant corand trapped the silver template in their cavity. The electron-withdrawing and electron-releasing groups like -NO₂, -Br, -C(CH₃)₃, and -OCH₃ were substituted on the bis-aldehyde to study their effects on the antimicrobial and anticancer activities of silver corates. The silver corates were found to have better antimicrobial activity than some of the standard drugs. Bromo-substituted corate-3, nitro-substituted corate-4, and tert-butyl-substituted corate-5 were found to be potent antibacterial agents among all. The bromo-substituted corate-3 was found to be the most potent fungicidal agent among all silver corates. The result of antineoplastic activity suggests that unsubstituted corate-1 and bromo-substituted corate-3 are potential candidates to be used as therapeutic molecules for cancer treatment, which requires further validation.

Systems Modeling Approach for Reducing the Risk of Healthcare-Associated Infections

Healthcare-associated infections (HAIs) are a major cause of concern because of the high levels of associated morbidity, mortality, and cost. In addition, children and intensive care unit (ICU) patients are more vulnerable to these infections due to low levels of immunity. Various medical interventions and statistical process control techniques have been suggested to counter the spread of these infections and aid early detection of an infection outbreak. Methods such as hand hygiene help in the prevention of HAIs and are well-documented in the literature. This chapter demonstrates the utilization of a systems methodology to model and validate factors that contribute to the risk of HAIs in a pediatric ICU. It proposes an approach that has three unique aspects: it studies the problem of HAIs as a whole by focusing on several HAIs instead of a single type, it projects the effects of interventions onto the general patient population using the system-level model, and it studies both medical and behavioral interventions and compares their effectiveness. This methodology uses a systems modeling framework that includes simulation, risk analysis, and statistical techniques for studying interventions to reduce the transmission likelihood of HAIs.

Bacterial biofilm formation on implantable devices and approaches to its treatment and prevention

In living organisms, biofilms are defined as complex communities of bacteria residing within an exopolysaccharide matrix that adheres to a surface. In the clinic, they are typically the cause of chronic, nosocomial, and medical device-related infections. Due to the antibiotic-resistant nature of biofilms, the use of antibiotics alone is ineffective for treating biofilm-related infections. In this review, we present a brief overview of concepts of bacterial biofilm formation, and current state-of-the-art therapeutic approaches for preventing and treating biofilms. Also, we have reviewed the prevalence of such infections on medical devices and discussed the future challenges that need to be overcome in order to successfully treat biofilms using the novel technologies being developed.

Effectiveness of antimicrobial-coated central venous catheters for preventing catheter-related blood-stream infections with the implementation of bundles: a systematic review and network meta-analysis

Background

Catheter-related blood-stream infections (CRBSIs) are the most common complication when using central venous catheters (CVCs). Whether coating CVCs under bundles could further reduce the incidence of CRBSIs is unclear. We aimed to assess the effectiveness of implementing the use of bundles with antimicrobial-coated CVCs for preventing catheter-related blood-stream infections.

Methods

In this systematic review and network meta-analyses, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library in addition to the EMBASE, MEDLINE, CINAHL, and Web of Science databases for studies published before July 2017. The primary outcome was the rate of CRBSIs per 1000 catheter-days, and the secondary outcome was the incidence of catheter colonization.

Results

Twenty-three studies revealed significant differences in the rate of CRBSIs per 1000 catheter-days between antimicrobial-impregnated and standard CVCs (RR 0.70, 95% CI 0.53–0.91, p = 0.008). Thirty-three trials were included containing 10,464 patients who received one of four types of CVCs. Compared with a standard catheter, chlorhexidine/silver sulfadiazine- and antibiotic-coated catheters were associated with lower numbers of CRBSIs per 1000 catheter-days (ORs and 95% CrIs: 0.64 (0.40–0.955) and 0.53 (0.25–0.95), respectively) and a lower incidence of catheter colonization (ORs and 95% CrIs: 0.44 (0.34–0.56) and 0.30 (0.20–0.46), respectively).

Conclusions

Outcomes are superior for catheters impregnated with chlorhexidine/silver sulfadiazine or other antibiotics than for standard catheters in preventing CRBSIs and catheter colonization under bundles. Compared with silver ion-impregnated CVCs, chlorhexidine/silver sulfadiazine antiseptic catheters resulted in fewer cases of microbial colonization of the catheter but did not reduce CRBSIs.

Electronic supplementary material

The online version of this article (10.1186/s13613-018-0416-4) contains supplementary material, which is available to authorized users.

Comparative Efficacy of Antimicrobial Central Venous Catheters in Reducing Catheter-Related Bloodstream Infections in Adults: Abridged Cochrane Systematic Review and Network Meta-Analysis

Background

The efficacy of antimicrobial central venous catheters (CVCs) remains questionable. In this network meta-analysis, we aimed to assess the comparative efficacy of antimicrobial CVC impregnations in reducing catheter-related infections in adults.

Methods

We searched 4 electronic databases (Medline, the Cochrane Central Register of Controlled Trials, Embase, CINAHL) and internet sources for randomized controlled trials, ongoing clinical trials, and unpublished studies up to August 2016. Studies that assessed CVCs with antimicrobial impregnation with nonimpregnated catheters or catheters with another impregnation were included. Primary outcomes were clinically diagnosed sepsis, catheter-related bloodstream infection (CRBSI), and all-cause mortality. We performed a network meta-analysis to estimate risk ratio (RR) with 95% confidence interval (CI).

Results

Sixty studies with 17255 catheters were included. The effects of 14 impregnations were investigated. Both CRBSI and catheter colonization were the most commonly evaluated outcomes. Silver-impregnated CVCs significantly reduced clinically diagnosed sepsis compared with silver-impregnated cuffs (RR, 0.54 [95% CI, .29-.99]). When compared to no impregnation, significant CRBSI reduction was associated with minocycline-rifampicin (RR, 0.29 [95% CI, .16-.52]) and silver (RR, 0.57 [95% CI, .38-.86]) impregnations. No impregnations significantly reduced all-cause mortality. For catheter colonization, significant decreases were shown by miconazole-rifampicin (RR, 0.14 [95% CI, .05-.36]), 5-fluorouracil (RR, 0.34 [95% CI, .14-.82]), and chlorhexidine-silver sulfadiazine (RR, 0.60 [95% CI, .50-.72]) impregnations compared with no impregnation. None of the studies evaluated antibiotic/antiseptic resistance as the outcome.

Conclusions

Current evidence suggests that the minocycline-rifampicin-impregnated CVC appears to be the most effective in preventing CRBSI. However, its overall benefits in reducing clinical sepsis and mortality remain uncertain. Surveillance for antibiotic resistance attributed to the routine use of antimicrobial-impregnated CVCs should be emphasized in future trials.

Drug eluting antimicrobial vascular catheters: Progress and promise

Vascular catheters are critical tools in modern healthcare yet present substantial risks of serious bloodstream infections that exact significant health and economic burdens. Drug-eluting antimicrobial vascular catheters have become important tools in preventing catheter-related bloodstream infections and their importance is expected to increase as significant initiatives are expanded to eliminate and make the occurrence of these infections unacceptable. Here we review clinically significant and emerging drug-eluting antimicrobial catheters within the categories of antibiotic, antiseptic, novel bioactive agents and energy-enhanced drug eluting antimicrobial catheters. Important representatives of each category are reviewed from the standpoints of mechanisms of action, physical-chemical properties, safety, in vitro and clinical effectiveness.

Catheter impregnation, coating or bonding for reducing central venous catheter-related infections in adults

BACKGROUND

The central venous catheter (CVC) is essential in managing acutely ill patients in hospitals. Bloodstream infection is a major complication in patients with a CVC. Several infection control measures have been developed to reduce bloodstream infections, one of which is impregnation of CVCs with various forms of antimicrobials (either with an antiseptic or with antibiotics). This review was originally published in June 2013 and updated in 2016.

OBJECTIVES

Our main objective was to assess the effectiveness of antimicrobial impregnation, coating or bonding on CVCs in reducing clinically-diagnosed sepsis, catheter-related blood stream infection (CRBSI), all-cause mortality, catheter colonization and other catheter-related infections in adult participants who required central venous catheterization, along with their safety and cost effectiveness where data were available. We undertook the following comparisons: 1) catheters with antimicrobial modifications in the form of antimicrobial impregnation, coating or bonding, against catheters without antimicrobial modifications and 2) catheters with one type of antimicrobial impregnation against catheters with another type of antimicrobial impregnation. We planned to analyse the comparison of catheters with any type of antimicrobial impregnation against catheters with other antimicrobial modifications, e.g. antiseptic dressings, hubs, tunnelling, needleless connectors or antiseptic lock solutions, but did not find any relevant studies. Additionally, we planned to conduct subgroup analyses based on the length of catheter use, settings or levels of care (e.g. intensive care unit, standard ward and oncology unit), baseline risks, definition of sepsis, presence or absence of co-interventions and cost-effectiveness in different currencies.

SEARCH METHODS

We used the standard search strategy of the Cochrane Anaesthesia, Critical and Emergency Care Review Group (ACE). In the updated review, we searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 3), MEDLINE (OVID SP; 1950 to March 2015), EMBASE (1980 to March 2015), CINAHL (1982 to March 2015), and other Internet resources using a combination of keywords and MeSH headings. The original search was run in March 2012.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that assessed any type of impregnated catheter against either non-impregnated catheters or catheters with another type of impregnation in adult patients cared for in the hospital setting who required CVCs. We planned to include quasi-RCT and cluster-RCTs, but we identified none. We excluded cross-over studies.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methodological procedures expected by Cochrane. Two authors independently assessed the relevance and risk of bias of the retrieved records. We expressed our results using risk ratio (RR), absolute risk reduction (ARR) and number need to treat to benefit (NNTB) for categorical data and mean difference (MD) for continuous data, where appropriate, with their 95% confidence intervals (CIs).

MAIN RESULTS

We included one new study (338 participants/catheters) in this update, which brought the total included to 57 studies with 16,784 catheters and 11 types of impregnations. The total number of participants enrolled was unclear, as some studies did not provide this information. Most studies enrolled participants from the age of 18, including patients in intensive care units (ICU), oncology units and patients receiving long-term total parenteral nutrition. There were low or unclear risks of bias in the included studies, except for blinding, which was impossible in most studies due to the catheters that were being assessed having different appearances. Overall, catheter impregnation significantly reduced catheter-related blood stream infection (CRBSI), with an ARR of 2% (95% CI 3% to 1%), RR of 0.62 (95% CI 0.52 to 0.74) and NNTB of 50 (high-quality evidence). Catheter impregnation also reduced catheter colonization, with an ARR of 9% (95% CI 12% to 7%), RR of 0.67 (95% CI 0.59 to 0.76) and NNTB of 11 (moderate-quality evidence, downgraded due to substantial heterogeneity). However, catheter impregnation made no significant difference to the rates of clinically diagnosed sepsis (RR 1.0, 95% CI 0.88 to 1.13; moderate-quality evidence, downgraded due to a suspicion of publication bias), all-cause mortality (RR 0.92, 95% CI 0.80 to 1.07; high-quality evidence) and catheter-related local infections (RR 0.84, 95% CI 0.66 to 1.07; 2688 catheters, moderate quality evidence, downgraded due to wide 95% CI).In our subgroup analyses, we found that the magnitudes of benefits for impregnated CVCs varied between studies that enrolled different types of participants. For the outcome of catheter colonization, catheter impregnation conferred significant benefit in studies conducted in ICUs (RR 0.70;95% CI 0.61 to 0.80) but not in studies conducted in haematological and oncological units (RR 0.75; 95% CI 0.51 to 1.11) or studies that assessed predominantly patients who required CVCs for long-term total parenteral nutrition (RR 0.99; 95% CI 0.74 to 1.34). However, there was no such variation for the outcome of CRBSI. The magnitude of the effects was also not affected by the participants' baseline risks.There were no significant differences between the impregnated and non-impregnated groups in the rates of adverse effects, including thrombosis/thrombophlebitis, bleeding, erythema and/or tenderness at the insertion site.

AUTHORS' CONCLUSIONS

This review confirms the effectiveness of antimicrobial CVCs in reducing rates of CRBSI and catheter colonization. However, the magnitude of benefits regarding catheter colonization varied according to setting, with significant benefits only in studies conducted in ICUs. A comparatively smaller body of evidence suggests that antimicrobial CVCs do not appear to reduce clinically diagnosed sepsis or mortality significantly. Our findings call for caution in routinely recommending the use of antimicrobial-impregnated CVCs across all settings. Further randomized controlled trials assessing antimicrobial CVCs should include important clinical outcomes like the overall rates of sepsis and mortality.

Silver particle monolayers — Formation, stability, applications

The formation of silver particle monolayers at solid substrates in self-assembly processes is thoroughly reviewed. Initially, various silver nanoparticle synthesis routes are discussed with the emphasis focused on the chemical reduction in aqueous media. Subsequently, the main experimental methods aimed at bulk suspension characterization are critically reviewed by pointing out their advantages and limitations. Also, various methods enabling the in situ studies of particle deposition and release kinetics, especially the streaming potential method are discussed. In the next section, experimental data are invoked illustrating the most important features of particle monolayer formation, in particular, the role of bulk suspension concentration, particle size, ionic strength, temperature and pH. Afterward, the stability of monolayers and particle release kinetics are extensively discussed. The results obtained by the ex situ AFM/SEM imaging of particles are compared with the in situ streaming potential measurements. An equivalency of both methods is demonstrated, especially in respect to the binding energy determination. It is shown that these experimental results can be adequately interpreted in terms of the hybrid theoretical approach that combines the bulk transport step with the surface blocking effects derived from the random sequential adsorption model. It is also concluded that the particle release kinetics is governed by the discrete electrostatic interactions among ion pairs on particle and substrate surfaces. The classical theories based on the mean-field (averaged) zeta potential concept proved inadequate. Using the ion pair concept the minor dependence of the binding energy on particle size, ionic strength, pH and temperature is properly explained. The final sections of this review are devoted to the application of silver nanoparticles and their monolayers in medicine, analytical chemistry and catalysis.

Kinetics of silver nanoparticle deposition at PAH monolayers: reference QCM results

The deposition kinetics of silver nanoparticles on Au/SiO2 /PAH substrate was studied under in situ conditions using the QCM method and the ex situ SEM imaging. Because of low dissipation, the Sauerbrey equation was used for calculating the mass per unit area (coverage). Measurements were done for various bulk suspension concentrations, flow rates, and ionic strengths. It was shown that particle deposition for the low coverage regime is governed by the bulk mass transfer step that results in a linear increase of the coverage with the time. A comparison of QCM and SEM results showed that the hydration of the silver monolayers was negligible. This allowed one to derive a universal kinetic equation that describes the mass transfer rates in the cell as a function of the bulk concentration, flow rate, and diffusion coefficient. Measurements were also performed for longer times and for various ionic strengths where the deposition kinetics and the maximum coverage of particles were determined. The experimental data confirmed a significant increase in the maximum coverage with ionic strength. This was interpreted as due to the decreasing range of the electrostatic interactions among deposited particles. These results were adequately interpreted in terms of the extended random sequential adsorption (eRSA) model. Additionally, it was shown that the QCM data matched the ex situ SEM results, indicating that the monolayer hydration was also negligible for higher coverage range. These results derived for the model silver nanoparticle system can be exploited as reference data for the interpretation of protein adsorption kinetics where the dry mass is needed in order to assess the extent of hydration.

Silver zeolite-loaded silicone elastomers: a multidisciplinary approach to synthesis and antimicrobial assessment

The fabrication of silicone elastomers containing organo-silane modified Ag-zeolites with potential for applications as antibacterial medical devices is demonstrated.

Success Rate and Complications of Internal Jugular Vein Catheterization With and Without Ultrasonography Guide

Background:

Central venous catheterization (CVC) is an important procedure in emergency departments (EDs). Despite existence of ultrasonography (US) devices in every ED, CVC is done using anatomical landmarks in many EDs in Iran.

Objectives:

This study aimed to compare the traditional landmark method vs. US-guided method of CVC placement in terms of complications and success rate.

Patients and Methods:

In this randomized controlled trial, patients who were candidate for internal jugular vein catheterization, and referred to Baqiyatallah Hospital ED were randomly allocated into US-guided CVC and anatomical landmarks guided CVC groups. Central vein access time, number of attempts, success rate, and complications in each group were evaluated. Mann-Whitney U, chi-square and Fisher exact tests along with Pearson and Spearman correlation coefficients were used to analyze the data.

Results:

Out of 100 patients, 56 were male and 44 were female. No significant differences were found between the US-guided and traditional landmark methods of CVC insertion in terms of age, gender, BMI, and site of catheter insertion. The mean access time was significantly lower in the US-guided group (37.12 ± 17.33 s vs. 63.42 ± 35.19 s, P < 0.001). The mean number of attempts was also significantly lower in the US-guided group (1.12 ± 0.3 vs. 1.58 ± 0.64 times, P < 0.001). Eighty-eight percent of patients in the US-guided group were catheterized in the first attempt, while 50% of patients in the traditional landmark group were catheterized in the second or more attempts (P < 0.001). The success rate was 100% in the US-guided group, while it was 88% in the landmark group (P = 0.013). Moreover, the rate of complications was significantly lower in the US-guided group (4% vs. 24%, P = 0.004).

Conclusions:

The US-guided method for CVC placement was superior to the traditional landmark method in terms of access time, number of attempts, success rate, and fewer complications.

The Role of Antifungals against Candida Biofilm in Catheter-Related Candidemia

Catheter-related bloodstream infection (C-RBSI) is one of the most frequent nosocomial infections. It is associated with high rates of morbidity and mortality. Candida spp. is the third most common cause of C-RBSI after coagulase-negative staphylococci and Staphylococcus aureus and is responsible for approximately 8% of episodes. The main cause of catheter-related candidemia is the ability of some Candida strains-mainly C. albicans and C. parapsilosis-to produce biofilms. Many in vitro and in vivo models have been designed to assess the activity of antifungal drugs against Candida biofilms. Echinocandins have proven to be the most active antifungal drugs. Potential options in situations where the catheter cannot be removed include the combination of systemic and lock antifungal therapy. However, well-designed and -executed clinical trials must be performed before firm recommendations can be issued.

Effectiveness of silver-impregnated central venous catheters for preventing catheter-related blood stream infections: a meta-analysis

OBJECTIVES

The purpose of this meta-analysis was to examine the effectiveness of silver-impregnated central venous catheters (CVCs) in preventing catheter bacterial colonization and catheter-related blood stream infections (CRBSIs).

METHODS

PubMed, Cochrane, and Embase databases were searched up to April 30, 2014. Studies in which other antiseptic reagents were used (e.g., chlorhexidine, octenidine dihydrochloride, urokinase rinses, benzalkonium chloride, rifampin-minocycline) were excluded. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Tests of heterogeneity and publication bias were performed.

RESULTS

Twelve studies were included in the meta-analysis. The studies enrolled a total of 2854 patients; 1440 received a standard CVC and 1414 received a silver-impregnated CVC. No significant difference in catheter bacterial colonization rates was found between silver-impregnated and standard CVCs (OR 0.907, 95% CI 0.758-1.087, p=0.290). No significant difference in CRBSI rates was found between silver-impregnated and standard CVCs (pooled OR 0.721, 95% CI 0.476-1.094, p=0.124). No significant heterogeneity or publication bias was noted.

CONCLUSIONS

Silver-impregnated CVCs are not associated with reduced rates of bacterial colonization or CRBSI.

Catheter impregnation, coating or bonding for reducing central venous catheter-related infections in adults

BACKGROUND

The central venous catheter (CVC) is a commonly used device in managing acutely ill patients in the hospital. Bloodstream infections are major complications in patients who require a CVC. Several infection control measures have been developed to reduce bloodstream infections, one of which is CVC impregnated with various forms of antimicrobials (either with an antiseptic or with antibiotics).

OBJECTIVES

We aimed to assess the effects of antimicrobial CVCs in reducing clinically diagnosed sepsis, established catheter-related bloodstream infection (CRBSI) and mortality.

SEARCH METHODS

We used the standard search strategy of the Cochrane Anaesthesia Review Group (CARG). We searched MEDLINE (OVID SP) (1950 to March 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 3, 2012), EMBASE (1980 to March 2012), CINAHL (1982 to March 2012) and other Internet resources using a combination of keywords and MeSH headings.

SELECTION CRITERIA

We included randomized controlled trials that assessed any type of impregnated catheter against either non-impregnated catheters or catheters with another impregnation. We excluded cross-over studies.

DATA COLLECTION AND ANALYSIS

We extracted data using the standard methods of the CARG. Two authors independently assessed the relevance and risk of bias of the retrieved records. We expressed our results using risk ratio (RR), absolute risk reduction (ARR) and number need to treat to benefit (NNTB) for categorical data and mean difference (MD) for continuous data where appropriate with their 95% confidence intervals (CIs).

MAIN RESULTS

We included 56 studies with 16,512 catheters and 11 types of antimicrobial impregnations. The total number of participants enrolled was unclear as some studies did not provide this information. There were low or unclear risks of bias in the included studies, except for blinding, which was impossible in most studies due to different appearances between the catheters assessed. Overall, catheter impregnation significantly reduced CRBSI, with an ARR of 2% (95% CI 3% to 1%), RR of 0.61 (95% CI 0.51 to 0.73) and NNTB of 50. Catheter impregnation also reduced catheter colonization, with an ARR of 10% (95% CI 13% to 7%), RR of 0.66 (95% CI 0.58 to 0.75) and NNTB of 10. However, catheter impregnation made no significant difference to the rates of clinically diagnosed sepsis (RR 1.0 (95% CI 0.88 to 1.13)) and all-cause mortality (RR 0.88 (95% CI 0.75 to 1.05)).In our subgroup analyses, we found that the magnitudes of benefits for impregnated CVCs varied in studies that enrolled different types of participants. For the outcome of catheter colonization, catheter impregnation conferred significant benefit in studies conducted in intensive care units (ICUs) (RR 0.68 (95% CI 0.59 to 0.78)) but not in studies conducted in haematological and oncological units (RR 0.75 (95% CI 0.51 to 1.11)) or studies that assessed predominantly patients who required CVCs for long-term total parenteral nutrition (TPN)(RR 0.99 (95% CI 0.74 to 1.34)). However, there was no such variation for the outcome of CRBSI. The magnitude of the effects was also not affected by the participants' baseline risks.There were no significant differences between the impregnated and non-impregnated groups in the rates of adverse effects, including thrombosis/thrombophlebitis, bleeding, erythema and/or tenderness at the insertion site.

AUTHORS' CONCLUSIONS

This review confirms the effectiveness of antimicrobial CVCs in improving such outcomes as CRBSI and catheter colonization. However, the magnitude of benefits in catheter colonization varied according to the setting, with significant benefits only in studies conducted in ICUs. Limited evidence suggests that antimicrobial CVCs do not appear to significantly reduce clinically diagnosed sepsis or mortality. Our findings call for caution in routinely recommending the use of antimicrobial-impregnated CVCs across all settings. Further randomized controlled trials assessing antimicrobial CVCs should include important clinical outcomes like the overall rates of sepsis and mortality.

Reduction of catheter-related bloodstream infections in preterm infants by the use of catheters with the AgION antimicrobial system

OBJECTIVE

The present study aims to assess if use of a silver zeolite-impregnated umbilical catheter (AgION technology) can decrease the occurrence of catheter-related bloodstream infection (CRBSIs) in preterm infants.

STUDY DESIGN

Infants with gestational age<30weeks were randomized to receive an AgION impregnated or non-impregnated polyurethane umbilical venous catheter (UVC). The primary endpoint was the incidence of CRBSIs during the time the UVC was in place.

RESULTS

We studied 86 infants, 41 of whom received the AgION catheter and 45 the non-impregnated catheter. During umbilical venous catheterization 2% of infants in the AgION group developed CRBSI in comparison with 22% of infants in the control group (p=0.005). AgION catheters were well tolerated and none of the patients showed signs attributable to silver toxicity.

CONCLUSIONS

The AgION-impregnated UVCs were effective in decreasing the development of CRBSIs in preterm infants compared to non-impregnated polyurethane UVCs.

Nanomedicine: a primer for surgeons

The advances in science have resulted in the emergence of nanotechnology, which deals with the design and use of tools and devices of size 1-100 nm. The application of nanotechnologies to medicine is thus termed nanomedicine. Significant research has been focused on this new and exciting field and this review article will describe the basics of nanomedicine. This is followed by its experimental and clinical applications in diagnostics, drug therapy and regenerative medicine. Safety issues of in vivo use of nanomaterials are also discussed. In the future, it is foreseen that nanomedicine will facilitate the development of personalized medicine and will have a major impact on the delivery of better healthcare.

Culture Positivity of CVCs Used for TPN: Investigation of an Association with Catheter-Related Infection and Comparison of Causative Organisms between ICU and Non-ICU CVCs

A relationship between central venous catheter (CVC) tip colonisation and catheter-related blood-stream infection (CRBSI) has been suggested. We examined culture positivity of CVC tips (colonised and infected CVCs) in a total parenteral nutrition (TPN) population. Our aims were to define the relationship between culture positivity and CRBSI, and to compare causative organisms between culture positive and CRBSI CVCS, and between ward and ICU CVCs. All patients receiving TPN via non-tunnelled CVCs during the study (1997–2009) were included. All CVC tips were analysed. Data were collated contemporaneously. A TPN audit committee determined whether CVC tip culture positivity reflected colonisation/CRBSI using CDC criteria. 1,392 patients received TPN via 2,565 CVCs over 15,397 CVC days. 25.4% of CVCs tips were culture positive, of these 32% developed CRBSI. There was a nonsignificant trend of higher Gram negative Bacilli isolation in ICU CVCs (P = 0.1), ward CVCs were associated with higher rates of staphylococcal isolation (P = 0.01). A similar pattern of organisms were cultured from CRBSI and culture positive CVCs. The consistent relationship between CRBSI and culture positive CVCs, and similar pattern of causative organisms further supports an aetiological relationship between culture positive CVC tips and CRBSI, supporting the contention that CVC culture-positivity may be a useful surrogate marker for CRBSI rates.

A review of epidural catheter-related infections

Spinal drug delivery is a generally safe and effective therapy for the treatment of both acute and chronic pain. However, it can be occasionally associated with significant complications, including neurologic injury, as a result of bleeding and infection in a confined space. This article focuses on risk factors for developing epidural catheter-related infections as well as strategies to minimize risks. Additionally, the diagnosis and management of epidural catheter-related infections, both superficial and deep, are discussed.

Resorcinarene bis-crown silver complexes and their application as antibacterial Langmuir-Blodgett films

Silver complexes of a cation binding supramolecular host, resorcinarene bis-crown (CNBC5) with propyl, nonyl, decyl and undecyl alkyl chains were investigated by NMR titration, picrate extraction and single crystal X-ray diffraction. Binding studies showed that both 1 : 1 and 1 : 2 (host-Ag(+)) complexes are present in solution with only a slight effect of the lower rim alkyl chain length on the binding constants (log K 4.0-4.2 for 1 : 2 complexes). Solid state complexes of the resorcinarene bis-crowns bearing either C(3) or C(11) chains were obtained. Single crystal X-ray analyses showed that both derivatives bind silver ions by metal-arene and Ag···O coordination from the crown ether bridges and from the solvent, and pack in layered or bilayered fashion. Furthermore, the amphiphilic nature of C11BC5 was demonstrated using the Langmuir balance technique. Langmuir-Blodgett films of the amphiphilic C11BC5-Ag complex were transferred onto a substrate and shown to possess antibacterial activity against E. coli.

Silver nanoparticles are broad-spectrum bactericidal and virucidal compounds

The advance in nanotechnology has enabled us to utilize particles in the size of the nanoscale. This has created new therapeutic horizons, and in the case of silver, the currently available data only reveals the surface of the potential benefits and the wide range of applications. Interactions between viral biomolecules and silver nanoparticles suggest that the use of nanosystems may contribute importantly for the enhancement of current prevention of infection and antiviral therapies. Recently, it has been suggested that silver nanoparticles (AgNPs) bind with external membrane of lipid enveloped virus to prevent the infection. Nevertheless, the interaction of AgNPs with viruses is a largely unexplored field. AgNPs has been studied particularly on HIV where it was demonstrated the mechanism of antiviral action of the nanoparticles as well as the inhibition the transmission of HIV-1 infection in human cervix organ culture. This review discusses recent advances in the understanding of the biocidal mechanisms of action of silver Nanoparticles.

Access technique and its problems in parenteral nutrition - Guidelines on Parenteral Nutrition, Chapter 9

Catheter type, access technique, and the catheter position should be selected considering to the anticipated duration of PN aiming at the lowest complication risks (infectious and non-infectious). Long-term (>7-10 days) parenteral nutrition (PN) requires central venous access whereas for PN <3 weeks percutaneously inserted catheters and for PN >3 weeks subcutaneous tunnelled catheters or port systems are appropriate. CVC (central venous catheter) should be flushed with isotonic NaCl solution before and after PN application and during CVC occlusions. Strict indications are required for central venous access placement and the catheter should be removed as soon as possible if not required any more. Blood samples should not to be taken from the CVC. If catheter infection is suspected, peripheral blood-culture samples and culture samples from each catheter lumen should be taken simultaneously. Removal of the CVC should be carried out immediately if there are pronounced signs of local infection at the insertion site and/or clinical suspicion of catheter-induced sepsis. In case PN is indicated for a short period (max. 7-10 days), a peripheral venous access can be used if no hyperosmolar solutions (>800 mosm/L) or solutions with a high titration acidity or alkalinity are used. A peripheral venous catheter (PVC) can remain in situ for as long as it is clinically required unless there are signs of inflammation at the insertion site.

Use of Galleria mellonella larvae to evaluate the in vivo anti-fungal activity of [Ag2(mal)(phen)3]

Larvae of the insect Galleria mellonella were employed to assess the in vivo antifungal efficacy of ([Ag(2)(mal)(phen)(3)]), AgNO(3) and 1,10-phenanthroline. Larvae pre-inoculated with these compounds were protected from a subsequent lethal infection by the yeast Candida albicans while larvae inoculated 1 and 4 h post-infection showed significantly increased survival (P < 0.01) compared to control larvae. Administration of these compounds resulted in an increase over 48 h in the density of insect haemocytes (immune cells) but there was no widespread activation of genes for antimicrobial peptides. This work demonstrates that G. mellonella larvae may be employed to ascertain the antifungal efficacy of silver(I) compounds and offers a rapid and effective means of assessing the in vivo activity of inorganic antimicrobial compounds.

Infection associated with central venous or epidural catheters: how to reduce it?

PURPOSE OF REVIEW

Central venous catheters are a leading source of nosocomial bloodstream infection with an estimated 10% mortality. Infection associated with epidural catheterization is an uncommon but devastating complication. Diagnosis of spinal epidural abscess requires a high index of suspicion and imaging techniques such as MRI. Early diagnosis and treatment will minimize permanent damage, but primary prevention should be the aim, which depends on proper patient evaluation and use of full aseptic precautions.

RECENT FINDINGS

Recent studies suggest that epidural infection is no longer as rare a complication as once thought and may be increasing. It is not clear whether this increase is related to an increase in reporting, an overall increase in the total number of epidurals (especially extended use) being performed, or a true increase in infection rate. Implementation of multistep prevention programs has been shown to decrease central venous catheter-related bloodstream infection rate. Antiseptic or antibiotic-impregnated central venous catheters are effective in decreasing central venous catheter-related bloodstream infections.

SUMMARY

Healthcare worker education and training are essential to create standardization of aseptic care. Continuous surveillance is necessary for identifying lapses in infection-control practices.

Diagnosis and prevention of catheter-related infections

PURPOSE OF REVIEW

To highlight the major advances in diagnosing and preventing catheter-related infections published in research articles published between March 2004 and May 2007.

RECENT FINDINGS

The challenge remains to make the diagnosis of catheter-related infection with good accuracy without catheter removal. The differential time to obtain positive qualitative blood culture appeared to be the most accurate available technique. Many catheter-related bloodstream infections are preventable. Simple interventions are often useful and multimodal programs are very efficacious, particularly in the intensive care setting. For long-term catheter-related bloodstream infection prevention, patient education appeared promising. Interesting evidence suggested that anticoagulant, by decreasing the biofilm formation, could decrease the risk of infection. For short-term central venous catheter-related infections research is ongoing on antiseptic dressings. Antiseptic lock appeared promising for preventing long-term central venous catheter bloodstream infections.

SUMMARY

Nowadays, multimodal programs of catheter infection prevention are efficacious. Levels of catheter-related bloodstream infection of more than one or two per 1000 catheter-days are usually only found in the intensive care unit. It is a prerequisite to evaluate the cost-effectiveness of new techniques of prevention. As catheter-related bloodstream infections become rarer, strategies limiting unnecessary removal of catheters need to be developed and tested.