Comparative in vitro efficacies of various catheter lock solutions

Taurolidine and Heparin as Catheter Lock Solution for Central Venous Catheters in Hemodialysis

BACKGROUND

Chronic kidney disease can lead to end-stage renal disease, and the prevalence is increasing. Many patients starting hemodialysis require central venous catheters (CVCs). Catheter-related bloodstream infections (CRBSIs) are a common complication and lead to significant morbidity and mortality. Interventions to prevent CRBSI include antimicrobial lock therapy but concern for the development of antimicrobial resistance and adverse effects. Nonantimicrobial antiseptics as catheter lock solutions have also been used. Taurolidine and heparin catheter lock solution is first approved by the Food and Drug Administration for the prevention of CRBSI in patients on hemodialysis. Taurolidine has a unique mechanism of action and favorable safety profile.

MECHANISM OF ACTION, PHARMACODYNAMICS, AND PHARMACOKINETICS

Taurolidine and heparin catheter lock solution have both antimicrobial and anticoagulant properties. Taurolidine is derivative of the amino acid taurine, and heparin is derived from porcine intestinal mucosa. Taurolidine not only damages microbial cell walls but also prevents the adherence of microorganisms to biological surfaces, preventing biofilm formation. Taurolidine and heparin catheter lock solution is intended to be used intraluminally within the catheter and should be aspirated. Because it is used locally, limited pharmacokinetic and pharmacodynamic data are available.

CLINICAL TRIALS

The LOCK-IT-100 trial is a randomized, double-blind, phase 3 study, which included 795 end-stage renal disease patients on hemodialysis with CVC. Taurolidine and heparin was compared with the control heparin alone. The results of the study showed a 71% risk reduction in CRBSI for taurolidine and heparin arm (95% confident interval, 38%-86%, P = 0.0006). Other studies have also shown that taurolidine lock solution leads to decreased CRBSI episodes. Several systematic reviews and meta-analysis consisted of taurolidine in adult, and pediatric populations also showed reduction in the incidence of CRBSIs.

THERAPEUTIC ADVANCE

Taurolidine and heparin lock solution represents a novel preventive strategy for those undergoing hemodialysis through a CVC by reducing the risk of CRBSI. This is significant progress because there are no other similar options available for patients for whom catheters are the only options for their life-saving treatment.

Novel intranasal phage-CaEDTA-ceftazidime/avibactam triple combination therapy demonstrates remarkable efficacy in treating Pseudomonas aeruginosa lung infection

Given the rise of multidrug-resistant (MDR) Pseudomonas aeruginosa infections, alternative treatments are needed. Anti-pseudomonal phage therapy shows promise, but its clinical application is limited due to the development of resistance and a lack of biofilm penetration. Recently, adjuvants like CaEDTA have shown the ability to enhance the effectiveness of combined antimicrobial agents. Here, we tested a phage-adjuvant combination and demonstrated the effectiveness of intranasally inhaled phage (KKP10) + CaEDTA in addition to ceftazidime/avibactam (CZA) for chronic P. aeruginosa lung infections. The results emphasize that intranasal inhalation of phage along with CaEDTA can successfully re-sensitize MDR P. aeruginosa to CZA in a triple combination treatment. This promising approach shows potential as a therapy for chronic respiratory tract infections.

Effectiveness of salvage catheters in home parenteral nutrition: A single-center study and systematic literature review

BACKGROUND & AIMS

There are sparse data regarding the rate of catheter salvage and long-term effectiveness of antibiotic lock treatment outcome after central line-associated bloodstream infections (CLABSI). Objectives were to analyze the effectiveness of central venous catheter (CVC) rescue strategy and its impact on catheter lifespan. Secondary objective included effectiveness of taurolidine+4% citrate in primary prevention, compared to a secondary prevention strategy, by analyzing infection incidence during two successive periods.

METHOD

Real-life 5-year observational study assessing CLABSI occurrence and CVC salvage outcomes in adult patients requiring Home Parenteral Nutrition (HPN) managed in a single-center Intestinal Failure Unit.

RESULTS

Over the 5-year period, there were 106 confirmed infections (63/143 patients (44%)). Infection incidence was 0.92/1000 catheter-days. Incidence was 1.02/1000 catheter-days during the taurolidine+4% citrate period while lower at 0.84/1000 catheter-days (p = 0.034) during the systematic taurolidine lock period. Of the total number of infections, 89 CVCs were immediately removed and 17 were salvaged. The success rate of catheter salvage with antibiotic lock was 82.4%, with 53% remaining CLABSI-free at one year. The salvage strategy extended catheter lifespan by a median 165 days (IQR 50-214). However, the rate of new infection was significantly higher in instances of salvage (71.4%) vs. removal (36%). Parenteral Nutrition (PN) ≥12 months (p = 0.002), PN (vs. hydroelectrolytic support) (p = 0.028) and self-management by patients (p = 0.049) were independent risk factors of CLABSI.

CONCLUSION

Catheter salvage appears to be an effective long-term strategy with >50% of CVCs remaining CLABSI-free at one year and a prolonged catheter life, although may expose to a more frequent and earlier infection recurrence.

CLINICAL TRIAL REGISTRATION

Cohort approved by the French CNIL (National Committee for Data Protection, authorization number CNIL 2015-25). referred to as "observational research", "non-interventional", or « non-RIPH ».

Ca-EDTA restores the activity of ceftazidime-avibactam or aztreonam against carbapenemase-producing Klebsiellapneumoniae infections

Developing an effective therapy to overcome carbapenemase-positive Klebsiella pneumoniae (CPKp) is an important therapeutic challenge that must be addressed urgently. Here, we explored a Ca-EDTA combination with aztreonam or ceftazidime-avibactam in vitro and in vivo against diverse CPKp clinical isolates. The synergy testing of this study demonstrated that novel aztreonam-Ca-EDTA or ceftazidime-avibactam-Ca-EDTA combination was significantly effective in eliminating planktonic and mature biofilms in vitro, as well as eradicating CPKp infections in vivo. Both combinations revealed significant therapeutic efficacies in reducing bacterial load in internal organs and protecting treated mice from mortality. Conclusively, this is the first in vitro and in vivo study to demonstrate that novel aztreonam-Ca-EDTA or ceftazidime-avibactam-Ca-EDTA combinations provide favorable efficacy and safety for successful eradication of carbapenemase-producing Klebsiella pneumoniae planktonic and biofilm infections.

Surface properties and bacterial adhesion on polyurethane central catheters: Impact of ethanol lock solution

It was shown in the literature that ethanol locks have a positive effect on preventing catheter-related infections in patients with central venous catheters without causing any microbial resistance. However, ethanol is known to interact with polyurethanes. The consequences of this interaction on the catheter surface properties were studied as it can impact the biocompatibility of the material and the adhesion phenomena onto the surface. No physical and chemical degradation was put into evidence, but low molecular weight compounds such as additives were extracted from the catheter bulk or migrated and exudated onto its surface. Nevertheless, as far as bacterial adhesion is concerned, after the catheter was locked and the lock removed, the surface modifications promoted no adhesion.

Actions of N-acetylcysteine, daptomycin, vancomycin, and linezolid on methicillin-resistant Staphylococcus aureus biofilms in the ventriculoperitoneal shunt infections: an experimental study

Background

Shunt systems are used to provide cerebrospinal fluid drainage in the treatment of hydrocephalus. Recently, antibiotic-impregnated shunt systems are used to prevent colonization in the ventriculoperitoneal catheters. Methicillin-resistant Staphylococcus aureus (MRSA) is the most common causative microorganism of shunt infections. The aim of the study is to investigate effects of several substances on MRSA biofilms in the ventriculoperitoneal catheters.

Methods

The present study consists of mainly eight groups (each has two subgroups as antibiotic-impregnated and nonantibiotic-impregnated catheters). In addition, each group contains six molds using MRSA strains. In this study, daptomycin (DAPT) (2 mg/ml), vancomycin (VAN) (10 mg/ml), linezolid (LIN) (2 mg/ml), N-acetylcysteine (NAC) (6 mg/ml), and various combinations of these substances were used to evaluate the treatment against MRSA using scanning electron microscope (SEM) images and microbiological enumeration.

Results

The colony count in the antibiotic-impregnated samples significantly decreased compared to nonantibiotic-impregnated samples in the MRSA, MRSA + DAPT, and MRSA + LIN groups (p < 0.01), respectively. Conversely, the colony count in antibiotic-impregnated samples significantly increased compared to nonantibiotic-impregnated samples in NAC + DAPT and NAC + VAN groups (p < 0.01), respectively.

Conclusions

The results showed that the use of antibiotic-impregnated catheters has a significant impact on the prevention of infection whereas the combination of NAC and DAPT showed better antibiofilm and antibacterial effects than other combinations on the prevention and treatment of nonantibiotic-impregnated catheter infections.

Antibacterial Activity of Some Molecules Added to Rabbit Semen Extender as Alternative to Antibiotics

Simple Summary

This study was conducted to evaluate the antibacterial activity of two aminopeptidase inhibitors and chitosan-based nanoparticles in liquid-stored rabbit semen. This study reports that the aminopeptidase inhibitors used to prevent bacterial growth could be used in semen extender as a suitable alternative to antibiotics.

Abstract

Although great attention is paid to hygiene during semen collection and processing, bacteria are commonly found in the semen of healthy fertile males of different species. As the storage of extended semen might facilitate bacterial growth, extenders are commonly supplemented with antibiotics. This study aimed to evaluate the antibacterial activity of ethylenediaminetetraacetic acid (EDTA), bestatin and chitosan-based nanoparticles added to rabbit semen extender and their effect on reproductive performance under field conditions. Four different extenders were tested, supplemented with antibiotics (TCG+AB), with EDTA and bestatin (EB), with EDTA, bestatin and chitosan-based nanoparticles (QEB) or without antibiotics (TCG-AB). Extended semen was cooled at 15 °C for three days. Cooled samples were examined for bacterial growth and semen quality every 24 h for 3 days. The enterobacteria count increased considerably during storage at 72 h in semen extended with TCG+AB and TCG-AB, while extenders EB and QEB showed a bacteriostatic effect over time. After 24, 48 and 72 h, quality characteristics were retained in all groups, with no significant motility differences, either in acrosome integrity, membrane functionality or the viability of spermatozoa. Additionally, bacterial concentration present in fresh semen did not affect reproductive performance. In conclusion, EDTA and bestatin exerted a potent bacteriostatic effect over time and could be used as an alternative to conventional antibiotics in rabbit semen extenders.

Destruction of Staphylococcus aureus biofilms by combining an antibiotic with subtilisin A or calcium gluconate

In S. aureus biofilms, bacteria are embedded in a matrix of extracellular polymeric substances (EPS) and are highly tolerant to antimicrobial drugs. We thus sought to identify non-antibiotic substances with broad-spectrum activity able to destroy the EPS matrix and enhance the effect of antibiotics on embedded biofilm bacteria. Among eight substances tested, subtilisin A (0.01 U/mL) and calcium gluconate (CaG, Ca²⁺ 1.25 mmol/L) significantly reduced the biomass of biofilms formed by at least 21/24 S. aureus isolates. Confocal laser scanning microscopy confirmed that they both eliminated nearly all the proteins and PNAG from the matrix. By contrast, antibiotics alone had nearly no effect on biofilm biomass and the selected one (oxytetracycline-OTC) could only slightly reduce biofilm bacteria. The combination of OTC with CaG or subtilisin A led to an additive reduction (average of 2 log₁₀ CFU/mL) of embedded biofilm bacteria on the isolates susceptible to OTC (MBC < 10 μg/mL, 11/24). Moreover, these two combinations led to a reduction of the embedded biofilm bacteria higher than 3 log₁₀ CFU/mL for 20–25% of the isolates. Further studies are now required to better understand the factors that cause the biofilm produced by specific isolates (20–25%) to be susceptible to the combinations.

Ethanol Lock Therapy Markedly Reduces Catheter-Related Blood Stream Infections in Adults Requiring Home Parenteral Nutrition: A Retrospective Study From a Tertiary Medical Center

BACKGROUND

The use of central venous catheter (CVC) access for home parenteral nutrition (HPN) is associated with catheter-related bloodstream infections (CRBSIs). There are limited data on the use of ethanol lock therapy (ELT) to prevent CRBSI in adult HPN patients. Our aim was to determine whether the routine institution of ELT decreased the incidence of CRBSI compared with historic controls at Emory University Hospital (EUH) in Atlanta, Georgia, USA.

METHODS

EUH medical records of adult HPN patients discharged with a tunneled, silicone CVC on ELT were retrospectively studied during a pre-hoc determined 14-month observation period (n = 87; 13,386 catheter days) and compared with clinically similar HPN patients from the same institution before institution of the ELT protocol for all appropriate patients. The ELT protocol involved instilling 2 mL of 70% ethanol into each catheter lumen daily after the HPN cycle, following initial flushing with normal saline.

RESULTS

Only 5 of 87 patients (5.7%) who received ELT were diagnosed with a CRBSI (0.45/1000 catheter days) during observation. We compared these data with our previously published clinically matched patient population from EUH (n = 22) receiving HPN via a silicone CVC without ELT. Of these historical controls, 45.5% were diagnosed with 1 or more CRBSIs (8.7/1000 catheter days) during observation (P < .001 vs the current ELT cohort).

CONCLUSIONS

In this retrospective study with historical controls from the same academic center, institution of ELT in adults requiring HPN via a silicone CVC was associated with a marked (19-fold) reduction in CRBSI.

Comparative efficacy of various antimicrobial lock solutions for preventing catheter-related bloodstream infections: A network meta-analysis of 9099 patients from 52 randomized controlled trials

OBJECTIVES

It remains uncertain which catheter lock solution (CLS) to prevent catheter-related bloodstream infections (CRBSI) works best and is safest for patients. This study was performed to compare the efficacy of different CLSs for the prevention of CRBSI and ranked these CLSs for practical consideration.

METHODS

The PubMed, Web of Science, Embase, and MEDLINE databases, earlier relevant meta-analyses, and the reference lists of included studies were searched. The primary outcome was CRBSI; secondary outcomes were catheter-related thrombosis and exit-site infections. A network meta-analysis was performed to estimate odds ratios (ORs) with 95% confidence intervals (CIs).

RESULTS

A total of 52 randomized controlled trials involving 9099 patients and evaluating 13 CLSs (single and combinations) were included. With regard to the quality of the evidence, the risk of bias was typically low or unclear (45 out of 52 trials, 86.5%). In the network meta-analysis, saline (OR 8.44, 95% CI 2.19-32.46), gentamicin+citrate (OR 2.92, 95% CI 1.32-6.42), ethanol (OR 5.33, 95% CI 1.22-23.32), and cloxacillin+heparin (OR 2.07, 95% CI 1.19-5.49) were associated with a greater effect on CRBSI than heparin.

CONCLUSIONS

This network meta-analysis showed that minocycline-ethylenediaminetetraacetic acid (EDTA) seemed to be the most effective for the prevention of CRBSI and exit-site infection, and cefotaxime+heparin seemed to be the most effective for catheter-related thrombosis.

In vitro comparison of efficacy of catheter locks in the treatment of catheter related blood stream infection

BACKGROUND & AIMS

Venous access used for parenteral nutrition (PN) application is extremely important for patients with intestinal failure. Potential loss of venous access might be a catastrophy for the patient. Catheter infections are a serious complication of PN application. Systemic administration of antibiotics as well as local antibiotic locks into the catheter to sterilize the catheter are used to treat catheter infections. However, there is no clear recommendation applying use of antibiotic locks, that would specify the type and concentration of antimicrobial medication. Our objective were to compare the efficacy of different types of antimicrobial lock therapy (especially taurolidine) and their concentrations to eradicate infectious agents.

METHODS

Bacterial strains of microorganisms (Staphylococcus epidermidis, Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Pseudomonas aeruginosa, multidrug-resistant P. aeruginosa, Candida albicans) were used. Subsequently, the catheter was exposed to the microbes and then was incubated with a specific lock for 2 or 24 h at 37 °C. We used these locks: ethanol 70%, taurolidine, gentamicine in concentrations 0,5, 1 and 10 mg/ml and vancomycine in concentrations 1, 5, and 10 mg/ml. The number of remaining CFU (colony forming units) was compared after incubation.

RESULTS

70% ethanol and taurolidine were most effective for all studied microorganisms. Gentamicine was more effective than vancomycine.

CONCLUSIONS

The most effective antimicrobial lock solutions to eradicate selected pathogenic agents were ethanol and taurolidine. Use of antibiotics is often effective after many hours of treatment and there is a risk of inadequate therapy.

International experience with minocycline, EDTA and ethanol lock for salvaging of central line associated bloodstream infections

BACKGROUND

The use of long-term central venous catheters (CVCs) could lead to serious bloodstream infections. Removal of the infected CVC and reinsertion of a new CVC are not always feasible and alternative lock therapy may be considered. We conducted a multicenter trial to assess the efficacy and safety of the lock therapy.

METHODS

Between October 2013 and August 2014, we prospectively enrolled 20 patients with catheter-related bloodstream infections (CRBSIs) or central line-associated bloodstream infections (CLABSIs) in our sister institutions in three countries including Brazil, Lebanon, and Japan. The 20 patients who received M-EDTA-EtOH lock therapy were compared to 24 control patients who had their CVCs removed and a new CVC inserted.

RESULTS

Both groups had comparable clinical characteristics. In the lock therapy group, 95% of the patients had microbiological eradication within 96 h after starting lock therapy versus 83% of the patients in the control group (p = .36). In the lock group, the CVC was salvaged and retained for a median of 21 days (range 7-51) from the onset of bacteremia.

CONCLUSION

Our study suggests that M-EDTA-EtOH lock therapy may be an effective intervention to salvage long-term CVCs in the setting of CLABSI/CRBSI and hemodialysis cancer patients with limited vascular access.

Sodium hypochlorite is more effective than 70% ethanol against biofilms of clinical isolates of Staphylococcus aureus

INTRODUCTION

Although disinfectants are used for eradication of bacteria from environmental surfaces, their antibiofilm efficacy is often not considered in determining the choice of disinfectant.

AIM

This study aimed to compare the effectiveness of 2 commonly used disinfectants, sodium hypochlorite and ethanol, against the planktonic and biofilm state of Staphylococcus aureus clinical isolates.

MATERIALS AND METHODS

Effect of 0.6% sodium hypochlorite and 70% ethanol was determined on the planktonic and biofilm states of 10 strong and weak biofilm formers through estimation of changes in colony forming unit counts and absorbance values. The morphologic changes were observed by scanning electron microscopy.

RESULTS

Significant difference in the efficacy of sodium hypochlorite and ethanol was observed against the biofilm (P = .004) as well as planktonic (P = .000) states of S aureus. However, no significant difference was observed in their activity against strong and weak biofilm formers. On electron microscopy, sodium hypochlorite was found to induce significant formation of craters and irregular depressions on the surface of strong biofilm formers.

CONCLUSIONS

Sodium hypochlorite demonstrated superior efficacy in controlling both planktonic and biofilm states of growth in S aureus. Furthermore, the characteristic morphologic changes observed in strong biofilm formers hint at its biofilm-specific activity.

Effect of Ethanol/Trisodium Citrate Lock on Microorganisms Causing Hemodialysis Catheter-Related Infections

Purpose

This in vitro study tested the effectiveness of a novel 30% ethanol/4% trisodium citrate (TSC) lock solution against the most common pathogens causing hemodialysis catheter-related infections.

Methods

Clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) (n=4), methicillin-sensitive S. aureus (MSSA) (n=8), methicillin-resistant Staphylococcus epidermidis (MRSE) (n=8), Pseudomonas aeruginosa (n=4) and Escherichia coli (n=4) were tested in duplicate. Bacterial suspensions of each isolate were made in a control solution of normal saline and Mueller-Hinton broth (MHB), and in a lock solution of ethanol 30%, TSC 4% and MHB. Suspensions were incubated at 37 °C for 48 h. Colony counts were determined from samples collected at t=0 h (before exposure to the ethanol/TSC lock), t=1 h (one hour after exposure to the ethanol/TSC lock), t=24 h and t=48 h. To confirm the absence of viable organisms in the lock solution, the remaining volume at 48 h was filtered through a 0.45 μm filter. The filter was rinsed with 15 mL sterile water and plated on tryptic soy agar (TSA).

Results

All controls demonstrated significant growth over 48 h. In the lock solutions, initial inocula were reduced to 0 viable colonies by t=1 h (6-log kill), and there was no growth at t=24 and 48 h. Filtering of lock solutions also showed no growth. These results were consistent among duplicates of all isolates.

Conclusions

The 30% ethanol/4% TSC lock solution consistently eradicated MRSA, MSSA, MRSE, P. aeruginosa and E. coli within 1 h of exposure. Experiments are currently underway to test this novel lock solution on preventing biofilm production by these pathogens.

Intravascular Catheters and Biofilm Control

Intravascular catheters are the most common cause of nosocomially acquired bloodstream infections. Bacteria found adhering to the intraluminal surfaces of catheters are the principal source and cause of these infections. Adherent bacteria overtime are known to form multicellular communities which become encased within a three dimensional matrix of extracellular polymeric material known as biofilms, which are thought to be responsible for persistent infections. Consequently, a number of technologies have been developed to help prevent and control biofilms in intravascular catheters. One such approach involves impregnating catheter material with antimicrobial agents. Unfortunately these methods are not universally effective in preventing catheter-related biofilm infections. Technologies that utilise antimicrobials, as catheter locks have been shown to have more potential for preventing biofilm formation and reducing the incidences of catheter related bloodstream infections (CRBSI). This article discusses the significance of biofilms in intravascular catheters and determines whether the treatments available today are proving to be effective for controlling biofilms and draws attention to future avenues which are being investigated to control biofilms and therefore CRBSI.

In vivo activity of fluconazole/tetracycline combinations in Galleria mellonella with resistant Candida albicans infection

OBJECTIVES

Treatment of azole-resistant Candida albicans infections continues to pose significant challenges. With limited options of licensed agents, drug combinations may be a practical treatment alternative. In our previous studies, the combinations minocycline/fluconazole (MINO/FLC) and doxycycline/fluconazole (DOXY/FLC) shown synergistic effects in vitro. It is necessary to explore their appropriate dosage, potential toxicity and in vivo efficacy.

METHODS

The Galleria mellonella infection model was employed to study the in vivo efficacy of MINO/FLC and DOXY/FLC by survival analysis, quantification of C. albicans fungal burden and histological studies.

RESULTS

The survival rates of G. mellonella larvae infected with lethal doses of resistant C. albicans CA10 increased significantly when treated with the drug combinations compared with FLC treatment alone, and the fungal burden was reduced by almost four-fold. The histopathological study showed that fewer infected areas in larvae were observed and the destructive degree was less when larvae were exposed to the drug combinations.

CONCLUSIONS

These findings suggest that combination of a tetracycline antibiotic (MINO or DOXY) with FLC has antifungal activity against azole-resistant C. albicans in vivo. This is in agreement with several previous in vitro studies and provides preliminary in vivo evidence that such a combination might be useful therapeutically.

Comparative Efficacies of Antimicrobial Catheter Lock Solutions for Fungal Biofilm Eradication in an in Vitro Model of Catheter-Related Fungemia

Fungal catheter-related bloodstream infections (CRBSIs)-primarily due to Candida species-account for over 12% of all CRBSIs, and have been progressively increasing in prevalence. They present significant health and economic burdens, and high mortality rates. Antimicrobial catheter lock solutions are an important prophylactic option for preventing fungal CRBSIs. In this study, we compared the effectiveness of two FDA-approved catheter lock solutions (heparin and saline) and three experimental antimicrobial catheter lock solutions-30% citrate, taurolidine-citrate-heparin (TCH), and nitroglycerin-citrate-ethanol (NiCE)-in an in vitro model of catheters colonized by fungi. The fungi tested were five different strains of Candida clinical isolates from cancer patients who contracted CRBSIs. Time-to-biofilm-eradication was assessed in the model with 15, 30, and 60 min exposures to the lock solutions. Only the NiCE lock solution was able to fully eradicate all fungal biofilms within 60 min. Neither 30% citrate nor TCH was able to fully eradicate any of the Candida biofilms in this time frame. The NiCE lock solution was significantly superior to TCH in eradicating biofilms of five different Candida species (p = 0.002 for all).

Use of Ethanol Lock Therapy to Reduce the Incidence of Catheter-Related Bloodstream Infections in Home Parenteral Nutrition Patients

BACKGROUND

Catheter-related bloodstream infection (CRBSI) is a serious complication for home parenteral nutrition (HPN) patients. To reduce the incidence of infection in frequently infected HPN patients, prophylactic ethanol lock therapy (ELT) was initiated.

METHODS

Nine patients were selected as candidates for ELT because of their history of recurrent CRBSI. Diagnosis of CRBSI was determined by symptoms correlating with positive peripheral and access device blood cultures. Medical-grade ethyl alcohol 25%-70% was instilled into the central venous access device and allowed to dwell for 2-4 hours. The incidence of CRBSI and catheter changes was compared before and after initiation of ELT.

RESULTS

Nine patients experienced 81 CRBSIs (8.3 per 1,000 catheter-days) before starting ELT vs 9 infections (2.7 per 1,000 catheter-days: relative risk [RR], 0.325; confidence interval [CI] 95%, 0.17-0.64) after ELT. Catheter changes were also reduced from 69 (7.0 per 1000 days) before ELT to 1 (0.3 per 1,000 days: RR, 0.043; CI 95%, 0.01-0.25) after ELT. No significant adverse effects were noted, although some patients complained of transient dizziness and nausea.

CONCLUSIONS

ELT shows promise in reducing the incidence of CRBSI in the frequently infected HPN population. Further studies are warranted.

Successful Salvage of Central Venous Catheters in Patients with Catheter-Related or Central Line-Associated Bloodstream Infections by Using a Catheter Lock Solution Consisting of Minocycline, EDTA, and 25% Ethanol

In cancer patients with long-term central venous catheters (CVC), removal and reinsertion of a new CVC at a different site might be difficult because of the unavailability of accessible vascular sites. In vitro and animal studies showed that a minocycline-EDTA-ethanol (M-EDTA-EtOH) lock solution may eradicate microbial organisms in biofilms, hence enabling the treatment of central line-associated bloodstream infections (CLABSI) while retaining the catheter in situ Between April 2013 and July 2014, we enrolled 30 patients with CLABSI in a prospective study and compared them to a historical group of 60 patients with CLABSI who had their CVC removed and a new CVC inserted. Each catheter lumen was locked with an M-EDTA-EtOH solution for 2 h administered once daily, for a total of 7 doses. Patients who received locks had clinical characteristics that were comparable to those of the control group. The times to fever resolution and microbiological eradication were similar in the two groups. Patients with the lock intervention received a shorter duration of systemic antibiotic therapy than that of the control patients (median, 11 days versus 16 days, respectively; P < 0.0001), and they were able to retain their CVCs for a median of 74 days after the onset of bacteremia. The M-EDTA-EtOH lock was associated with a significantly decreased rate of mechanical and infectious complications compared to that of the CVC removal/reinsertion group, who received a longer duration of systemic antimicrobial therapy. (This study has been registered at ClinicalTrials.gov under registration no. NCT01539343.).

In Vitro Approach for Identification of the Most Effective Agents for Antimicrobial Lock Therapy in the Treatment of Intravascular Catheter-Related Infections Caused by Staphylococcus aureus

Infection of intravascular catheters by Staphylococcus aureus is a significant risk factor within the health care setting. To treat these infections and attempt salvage of an intravascular catheter, antimicrobial lock solutions (ALSs) are being increasingly used. However, the most effective ALSs against these biofilm-mediated infections have yet to be determined, and clinical practice varies greatly. The purpose of this study was to evaluate and compare the efficacies of antibiotics and antiseptics in current clinical use against biofilms produced by reference and clinical isolates of S. aureus Static and flow biofilm assays were developed using newly described in vivo-relevant conditions to examine the effect of each agent on S. aureus within the biofilm matrix. The antibiotics daptomycin, tigecycline, and rifampin and the antiseptics ethanol and Taurolock inactivated established S. aureus biofilms, while other commonly used antistaphylococcal antibiotics and antiseptic agents were less effective. These findings were confirmed by live/dead staining of S. aureus biofilms formed and treated within a flow cell model. The results from this study demonstrate the most effective clinically used agents and their concentrations which should be used within an ALS to treat S. aureus-mediated intravascular catheter-related infections.

From Biology to Drug Development: New Approaches to Combat the Threat of Fungal Biofilms

Fungal infections constitute a major threat to an escalating number of critically ill patients. Fungi are eukaryotic organisms and, as such, there is a limited armamentarium of antifungal drugs, which leads to high mortality rates. Moreover, fungal infections are often associated with the formation of biofilms, which contribute to virulence and further complicate treatment due to the high level of antifungal drug resistance displayed by sessile cells within these microbial communities. Thus, the treatment of fungal infections associated with a biofilm etiology represents a formidable and unmet clinical challenge. The increasing importance and awareness of fungal biofilms is reflected by the fact that this is now an area of very active research. Studies in the last decade have provided important insights into fungal biofilm biology, physiology, and pathology, as well as into the molecular basis of biofilm resistance. Here we discuss how this accumulated knowledge may inform the development of new antibiofilm strategies and therapeutics that are urgently needed.

Fungal Biofilms: In Vivo Models for Discovery of Anti-Biofilm Drugs

During infection, fungi frequently transition to a biofilm lifestyle, proliferating as communities of surface-adherent aggregates of cells. Phenotypically, cells in a biofilm are distinct from free-floating cells. Their high tolerance of antifungals and ability to withstand host defenses are two characteristics that foster resilience. Biofilm infections are particularly difficult to eradicate, and most available antifungals have minimal activity. Therefore, the discovery of novel compounds and innovative strategies to treat fungal biofilms is of great interest. Although many fungi have been observed to form biofilms, the most well-studied is Candida albicans. Animal models have been developed to simulate common Candida device-associated infections, including those involving vascular catheters, dentures, urinary catheters, and subcutaneous implants. Models have also reproduced the most common mucosal biofilm infections: oropharyngeal and vaginal candidiasis. These models incorporate the anatomical site, immune components, and fluid dynamics of clinical niches and have been instrumental in the study of drug resistance and investigation of novel therapies. This chapter describes the significance of fungal biofilm infections, the animal models developed for biofilm study, and how these models have contributed to the development of new strategies for the eradication of fungal biofilm infections.

Anticoagulants and antiplatelet agents for preventing central venous haemodialysis catheter malfunction in patients with end-stage kidney disease

BACKGROUND

Catheter malfunction, including thrombosis, is associated with reduced dialysis adequacy, as well as an increased risk of catheter-related bacteraemia and mortality. The role of anticoagulants in the prevention of catheter malfunction remains uncertain.

OBJECTIVES

This review aimed to compare the prophylactic effect of different anticoagulant agents, preparations, doses and administration on the incidence of central venous haemodialysis catheter-related malfunction and sepsis in patients with end-stage kidney disease (ESKD).

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register to 7 January 2016 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included all randomised controlled trials (RCT) assessing anticoagulants compared with conventional care for the prevention of catheter malfunction in adult patients receiving haemodialysis for ESKD.

DATA COLLECTION AND ANALYSIS

The primary outcome was catheter malfunction defined as a catheter blood flow of 200 mL/min or less, or as defined by study authors. Secondary outcomes were catheter-related bacteraemia, all-cause mortality and bleeding events. Relative risks (RR) with 95% confidence intervals (CI) for individual studies were pooled using random effects models within treatment classes. Analyses were conducted by class, with subgroup analyses performed of individual agents within classes.

MAIN RESULTS

We included 27 studies (3003 participants) that were followed up for a median of six months. Study interventions included alternative anticoagulant locking solutions (19 studies, 2216 patients), systemic agents (6 studies, 664 patients) and low or no dose heparin (2 studies, 123 patients). The most common comparison treatment was a locking solution of heparin 5000 IU/mL, used in 17 studies. No significant effect on catheter malfunction was observed for alternative anticoagulant locking solutions (RR 0.96, 95% CI 0.74 to 1.26), systemic agents (RR 0.59, 95% CI 0.28 to 1.23), or low or no dose heparin (RR 0.90, 95% CI 0.10 to 8.31). A significant reduction on incidence of catheter-related bacteraemia was observed for alternative anticoagulant locking solutions (RR 0.46, 95% CI 0.32 to 0.66) but not systemic agents (RR 2.41, 95% CI 0.89 to 6.55), and could not be assessed in reports of low or no dose heparin studies. No significant effect on all-cause mortality was observed for alternative anticoagulant locking solutions (RR 0.88, 95% CI 0.54 to 1.43) or systemic agents (RR 0.78, 95% CI 0.37 to 1.65), and was not reported in studies of low or no dose heparin. Bleeding events were only reported in eight studies, including only 2/5 studies of systemic warfarin, with no clear effect demonstrated (RR 1.43, 95% CI 0.86 to 2.39). For individual agents, recombinant tissue plasminogen (rt-PA) was the only locking solution shown to reduce catheter malfunction (RR 0.58, 95% CI 0.37 to 0.91) based on the results of a single study. No significant on catheter malfunction was observed for other individual classes of alternative anticoagulant locking solutions (citrate: RR 1.14, 95% CI 0.76 to 1.69; antibiotic: RR 1.48, 95% CI 0.79 to 2.77; ethanol: RR 0.88, 95% CI 0.21 to 3.67). On the other hand, all individual classes of alternative anticoagulant locking solutions, except ethanol, reduced catheter-related bacteraemia (citrate: RR 0.49, 95% CI 0.36 to 0.68; antibiotic: RR 0.27, 95% CI 0.11 to 0.70; rt-PA: RR 0.35, 95% CI 0.13 to 0.93; ethanol: RR 0.33, 95% CI 0.03 to 4.05). No significant effect on all-cause mortality was observed for any individual agent within the class of alternative locking solutions. Studies were mainly of low quality and underpowered with an average participant number of 75 and study duration of six months. The interpretation of the study evidence was further limited by the variation in tested interventions and outcome reporting.

AUTHORS' CONCLUSIONS

The relative net benefit of anticoagulant therapies for prevention of catheter malfunction remains uncertain. Multiple agents appear to reduce catheter-related bacteraemia although the lack of clear assessment of harms and the limitations of study quality mean these results should be interpreted with caution. Methodological approaches can be used to avoid methods of reporting unduly affecting on the results of meta-analyses incorporating studies employed mixed reporting methods. Further high quality randomised studies, including safety outcomes, are needed.

In vitro efficacy of daptomycin and teicoplanin combined with ethanol, clarithromycin or gentamicin as catheter lock solutions

Background

Despite widespread use, optimum choice of antimicrobial agents, concentrations, combinations and exposure times have not been determined for antibiotic lock technique (ALT). Our objective was to evaluate the efficacy of different antibiotic combinations using an in vitro model of catheter-related infection. Daptomycin (DAP) 5 mg/mL, teicoplanin (TEC) 5 mg/mL, both alone and combined with gentamicin (GM) 2.5 mg/mL, clarythromycin (CLA) 5 mg/mL or ethanol 35 % were evaluated against four clinical strains of methicillin resistant coagulase negative staphylococci. Lock solutions were renewed every 24 h.

Results

After 72 h catheters were reincubated with culture media to investigate bacterial regrowth. All antibiotic combinations resulted in significant reductions (p < 0.05) of Log(10) cfu/mL at 72 h for both organisms compared with controls. DAP resulted in significant reductions of Log(10) for all organism versus TEC (p = 0.001). Only DAP reached the limit of detection at 72 h, however did not prevent regrowth after 24 h of ALT removal. DAP + Ethanol and TEC + ethanol eradicated biofilm at 72 h, but only DAP + ethanol (against all strains) and DAP + CLA (against two strains) prevented regrowth at 24 h after ALT removal.

Conclusions

Based on these data, ALT with DAP + ethanol and DAP + CLA should be explored in clinical trials.

In vitro activity of taurolidine gel on bacteria associated with periodontitis

OBJECTIVES

The purpose of this in vitro study was to determine the antimicrobial activity of two different taurolidine gel formulations in comparison with minocycline microspheres.

METHODS

Three percent taurolidine gel (TLG3) and 2 % taurolidine gel (TLG2) were compared to minocycline microspheres (MINO) against single bacterial species and a 12-species-mixture. The antimicrobial activity was proven by determination of minimal inhibitory concentrations (MICs), killing assays, after exposure of the antimicrobials as well as within a biofilm.

RESULTS

The MICs against the single species were between 0.5 and 2 mg/ml of taurolidine. MICs of the used mixed microbiota were 1.5 mg/ml (TLG3) and 4 mg/ml (TLG2). Fusobacterium nucleatum and Porphyromonas gingivalis were completely killed by 10 % TLG3 and TLG2 (equivalent to 3 and 2 mg/ml taurolidine) after 6 h. The mixture of 12 species was not completely killed by any of the test substances. Taurolidine gels showed a post-antimicrobial activity, however being less than that of MINO. On biofilms, taurolidine gels reduced concentration dependently the colony forming unit (CFU) counts (multi-species biofilms by 3.63 log10 after 100 % (30 mg/ml) of TLG3), reductions were 2.12 log10 after MINO (1000 μg/ml minocycline).

CONCLUSIONS

Taurolidine gel formulations exert antimicrobial activity against bacteria associated with periodontal disease. Nevertheless, a complete elimination of biofilms seems to be impossible and underlines the importance of mechanical removal of biofilms prior to application of the antimicrobial.

CLINICAL RELEVANCE

Taurolidine gels may represent a potential alternative for adjunctive topical antimicrobial treatment in periodontitis and infectious peri-implant diseases.

EDTA: An Antimicrobial and Antibiofilm Agent for Use in Wound Care

Significance: Methods employed for preventing and eliminating biofilms are limited in their efficacy on mature biofilms. Despite this a number of antibiofilm formulations and technologies incorporating ethylenediaminetetraacetic acid (EDTA) have demonstrated efficacy on in vitro biofilms. The aim of this article is to critically review EDTA, in particular tetrasodium EDTA (tEDTA), as a potential antimicrobial and antibiofilm agent, in its own right, for use in skin and wound care. EDTA's synergism with other antimicrobials and surfactants will also be discussed. Recent Advances: The use of EDTA as a potentiating and sensitizing agent is not a new concept. However, currently the application of EDTA, specifically tEDTA as a stand-alone antimicrobial and antibiofilm agent, and its synergistic combination with other antimicrobials to make a "multi-pronged" approach to biofilm control is being explored. Critical Issues: As pathogenic biofilms in the wound increase infection risk, tEDTA could be considered as a potential "stand-alone" antimicrobial/antibiofilm agent or in combination with other antimicrobials, for use in both the prevention and treatment of biofilms found within abiotic (the wound dressing) and biotic (wound bed) environments. The ability of EDTA to chelate and potentiate the cell walls of bacteria and destabilize biofilms by sequestering calcium, magnesium, zinc, and iron makes it a suitable agent for use in the management of biofilms. Future Direction: tEDTA's excellent inherent antimicrobial and antibiofilm activity and proven synergistic and permeating ability results in a very beneficial agent, which could be used for the development of future antibiofilm technologies.

Chemical stability of heparin, isopropanol, and ethanol line lock solutions

BACKGROUND

Ethanol line locks are used in the US to prevent catheter associated bloodstream infections. Heparin precipitates in solution with ethanol. However, isopropanol may reduce precipitate formation. We aimed to determine the chemical stability of heparin, isopropanol, and ethanol line lock for a 10 day period at 2-8°C and 25°C.

METHODS

Forty samples were prepared for analysis. Each sample was prepared identically using a 5 ml syringe capped with a Combi-stopper: 1 ml 70% isopropanol, 1 ml 70% ethanol, and 1 ml heparin sodium 10 IU/ml. Twenty syringes were stored at 2-8°C and 20 at 25°C. Analysis was carried out on days 1, 3, 6, 8, and 10 with a single syringe from each condition being tested in duplicate. Samples were assessed visually. Sub-visible particle count analysis was carried out using a CLIMET particle counting system. Heparin concentration was analysed using an anti-Xa assay. Ethanol and isopropanol concentrations were analysed by gas chromatography.

RESULTS

Samples remained clear and colourless throughout the study. Sub-visible particle counts remained within limits specified in British Pharmacopoeia 2013 when stored at 2-8°C and 25°C, 60% humidity for up to 10 days. There was no significant change in ethanol or isopropanol concentration during the study. However, heparin activity fell by >10% after 1 day storage and to 65% of original activity after 10 days.

CONCLUSIONS

This study shows that addition of isopropanol to heparin and ethanol prevents precipitation. However, this solution shows a progressive decline in heparin activity over time making it unsuitable for extended shelf life.

Ethanol Lock Technique: Review of the Literature

Central venous catheters (CVCs) are commonly used among adult and pediatric patients for administration of fluids, medications, and nutrition. Central line–associated (CLA) bloodstream infection (BSI) is a serious complication following CVC insertion. The aim of this review is to summarize available data regarding the ethanol lock technique, which is a proposed method for sterilizing the lumen of the catheter by instilling an ethanol solution and allowing it to dwell in the catheter for a certain amount of time. Studies on ethanol lock technique differ in ethanol concentrations, luminal dwell times, catheter types, inclusion of anticoagulants, use of systemic antibiotics, and use of the technique for prevention or for treatment of CLA BSI. In vitro studies demonstrate the efficacy of ethanol in the eradication of various pathogens. Definitive catheter integrity data are limited. Clinical trials report tolerable adverse events with ethanol locks, as well as encouraging results for prevention and treatment of CLA BSI.

In-vitro activity of taurolidine on single species and a multispecies population associated with periodontitis

The antimicrobial activity of taurolidine was compared with minocycline against microbial species associated with periodontitis (four single strains and a 12-species mixture). Minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs), killing as well as activities on established and forming single-species biofilms and a 12-species biofilm were determined. The MICs of taurolidine against single species were always 0.31 mg/ml, the MBCs were 0.64 mg/ml. The used mixed microbiota was less sensitive to taurolidine, MIC and the MBC was 2.5 mg/ml. The strains and the mixture were completely killed by 2.5 mg/ml taurolidine, whereas 256 μg/ml minocycline reduced the bacterial counts of the mixture by 5 log10 colony forming units (cfu). Coating the surface with 10 mg/ml taurolidine or 256 μg/ml minocycline prevented completely biofilm formation of Porphyromonas gingivalis ATCC 33277 but not of Aggregatibacter actinomycetemcomitans Y4 and the mixture. On 4.5 d old biofilms, taurolidine acted concentration dependent with a reduction by 5 log10 cfu (P. gingivalis ATCC 33277) and 7 log10 cfu (A. actinomycetemcomitans Y4) when applying 10 mg/ml. Minocycline decreased the cfu counts by 1-2 log10 cfu independent of the used concentration. The reduction of the cfu counts in the 4.5 d old multi-species biofilms was about 3 log10 cfu after application of any minocycline concentration and after using 10 mg/ml taurolidine. Taurolidine is active against species associated with periodontitis, even within biofilms. Nevertheless a complete elimination of complex biofilms by taurolidine seems to be impossible and underlines the importance of a mechanical removal of biofilms prior to application of taurolidine.

Stability and compatibility of antimicrobial lock solutions

PURPOSE

Published stability and compatibility data on a growing array of solutions used for antimicrobial lock therapy (ALT) are reviewed.

SUMMARY

ALT involves the instillation of a highly concentrated antimicrobial, often in combination with an anticoagulant, into a central venous catheter (CVC) lumen; this technique is often used for prophylaxis after CVC insertion or as an adjunctive treatment in cases of central line-associated bloodstream infection (CLABSI) if catheter removal is not feasible. Optimal selection of stable and compatible antimicrobials and additives can maximize catheter dwell times, streamline pharmacy compounding practices, and help ensure patient safety. Of 98 articles on ALT solutions identified in a literature search, 17 met the prespecified criteria for the use of validated stability and compatibility methodology. Antimicrobials active against common CLABSI pathogens that may be appropriate for ALT include cefazolin, cefotaxime, ceftazidime, ciprofloxacin, daptomycin, gentamicin, linezolid, telavancin, ticarcillin-clavulanic acid, and vancomycin; validated data demonstrate the stability of these agents in solution with heparin or nonheparin anticoagulants over 72-96 hours or longer. Other antifungal agents and antiinfectives (e.g., ethyl alcohol) have been used in specific patients and ALT situations. The prolonged stability of several antimicrobial-additive combinations may allow for extended dwell times and less frequent lock solution exchanges.

CONCLUSION

Pharmacists' knowledge of diverse combinations of antimicrobial agents and additives in lock solutions, including several shown to be stable and compatible for extended periods, can help expand and optimize the use of ALT in both treatment and prophylactic modalities.

[Infections of central venous catheters in home parenteral nutrition: a retrospective monocentric study over 2 years]

BACKGROUND AND STUDY AIMS

Infection of the central venous catheter (CVC) is the main aggravating factor of parenteral nutrition. The aim of this study was to determine the ecology of these infections in our home parenteral nutrition center and to evaluate our care protocol.

PATIENTS AND METHODS

The present study was monocentric and retrospective, and was conducted in the parenteral nutrition service of the Marseille University Hospital between 1 January 2011 and 31 May 2012. During this period, all the children who presented fever and a positive hemoculture in a medical emergency were taken into account, and the characteristics of the infection were analyzed.

RESULTS

After 17 months, 17 children had been subject to an infection in their central catheter: 47 bacteremia were identified, which is equivalent to 5.4 infections for 1000 days of CVC. An average 2.8 hemocultures were performed during this time. The most common bacterium was Staphylococcus hominis. The children affected by a digestive stoma or by a gastrostomy were not subject to more infections and their ecology was not different. All the children were referred to the hospital and treated with an intravenous antibiotic through the CVC.

DISCUSSION

As expected during the time of the study, the infection rate was very high. This finding led us to reassess our prevention protocol. It is also very likely that the number of infections was overestimated due to the protocol for sampling in the hemocultures and their subsequent analysis. Lastly, some children relapsed easily, although no predisposing factor was found in the present study. The therapy chosen was in agreement with the best practices and the ecology recovered.

CONCLUSION

The high number of infections observed during the study encourages a prospective evaluation of current practices.

Future directions for anti-biofilm therapeutics targeting Candida

While proliferating in its most common mode of growth, a biofilm, Candida spp. exhibit increased resistance to available antifungal agents. These adherent communities are difficult to eradicate and often responsible for treatment failures. New therapies are urgently needed to treat a variety of Candida biofilm infections in the medical setting. This review discusses the medical relevance of Candida biofilms, the drug resistance associated with this mode of growth, and approaches to combat these resilient infections.

Adjunctive management of central line-associated bloodstream infections with 70% ethanol-lock therapy

OBJECTIVES

Ethanol is bactericidal against most pathogens implicated in central line-associated bloodstream infections (CLABSIs) and biofilms. Current Infectious Diseases Society of America guidelines cite insufficient evidence to support adjunctive ethanol-lock therapy (ELT) for central venous catheter (CVC) salvage in patients with CLABSI in combination with systemic antimicrobial treatment. We evaluated the safety and potential efficacy of 70% ELT for CLABSI at our institution after implementation of a hospital ELT protocol.

METHODS

We collected data on all patients treated with adjunctive 70% ELT for catheter salvage from September 2009 to September 2011 and assessed clinical outcomes and adverse events associated with ELT.

RESULTS

Sixty-eight hospitalized patients received 70% ELT for CVC salvage: 45 (66%) met the criteria for CLABSI. Five (11%) had persistent or recurrent bacteraemia triggering CVC removal; 28 (62%) preserved their CVC long term. There were no documented adverse events associated with ELT.

DISCUSSION

Adjunctive 70% ELT is an inexpensive, well-tolerated option for CVC salvage in patients with CLABSI and warrants further investigation.

Antibiotic-lock therapy for long-term catheter-related bacteremia: a review of the current evidence

Catheter-related bloodstream infections (CRBSIs) are a major cause of morbidity and mortality, especially among patients receiving hemodialysis, parenteral nutrition and chemotherapy. Antibiotic-lock therapy (ALT) represents a promising technique in the modern treatment of CRBSIs. In this review, we attempt to clarify the potential role of ALT in the treatment of long-term catheter-related bacteremia, based on the available evidence from published studies reporting on this issue. We identified 28 articles that were considered appropriate to be included in our review, only three of which were comparative studies. There is some evidence that ALT administered concurrently with systemic therapy may represent a significant therapeutic approach for CRBSIs involving long-term catheters. Prolonged infection-free catheter survival in the reported series is suggestive of sterilization of the catheters by ALT. The only reported comparison shows better outcome with ALT than with catheter exchange. Immunodeficient states, such as HIV, and the use of totally implanted devices instead of tunneled catheters may predispose to CRBSI treatment failure. No serious adverse effects, such as emergence of resistance or increased infectious complications, were found to be associated with the use of ALT in the reviewed studies. However, more comparative studies should be performed to examine this important therapeutic issue further.

Ethanol causes protein precipitation--new safety issues for catheter locking techniques

OBJECTIVE

The ethanol lock technique has shown great potential to eradicate organisms in biofilms and to treat or prevent central venous catheter related infections. Following instillation of ethanol lock solution, however, the inherent density gradient between blood and ethanol causes gravity induced seepage of ethanol out of the catheter and blood influx into the catheter. Plasma proteins so are exposed to highly concentrated ethanol, which is a classic agent for protein precipitation. We aimed to investigate the precipitating effect of ethanol locks on plasma proteins as a possible cause for reported catheter occlusions.

METHODS

Plasma samples were exposed in-vitro to ethanol (concentrations ranging from 7 to 70 v/v%) and heparin lock solutions. In catheter studies designed to mimic different in-vivo situations, the catheter tip was placed in a plasma reservoir and the material contained within the catheter was analyzed after ethanol lock instillation. The samples underwent standardized investigation for protein precipitation.

RESULTS

Protein precipitation was observed in plasma samples containing ethanol solutions above a concentration of 28%, as well as in material retrieved from vertically positioned femoral catheters and jugular (subclavian) catheters simulating recumbent or head down tilt body positions. Precipitates could not be re-dissolved by dilution with plasma, urokinase or alteplase. Plasma samples containing heparin lock solutions showed no signs of precipitation.

CONCLUSIONS

Our in-vitro results demonstrate that ethanol locks may be associated with plasma protein precipitation in central venous catheters. This phenomenon could be related to occlusion of vascular access devices locked with ethanol, as has been reported. Concerns should be raised regarding possible complications upon injection or spontaneous gravity induced leakage of such irreversibly precipitated protein particles into the systemic circulation. We suggest limiting the maximum advisable concentration of ethanol to 28 v/v% in catheter lock solutions.

Bench-to-bedside review: Challenges of diagnosis, care and prevention of central catheter-related bloodstream infections in children

Central venous catheters (CVCs) are indispensable in modern pediatric medicine. CVCs provide secure vascular access, but are associated with a risk of severe complications, in particular bloodstream infection. We provide a review of the recent literature about the diagnostic and therapeutic challenges of catheter-related bloodstream infection (CRBSI) in children and its prevention. Variations in blood sampling and limitations in blood culturing interfere with accurate and timely diagnosis of CRBSI. Although novel molecular testing methods appear promising in overcoming some of the present diagnostic limitations of conventional blood sampling in children, they still need to solidly prove their accuracy and reliability in clinical practice. Standardized practices of catheter insertion and care remain the cornerstone of CRBSI prevention although their implementation in daily practice may be difficult. Technology such as CVC impregnation or catheter locking with antimicrobial substances has been shown less effective than anticipated. Despite encouraging results in CRBSI prevention among adults, the goal of zero infection in children is still not in range. More high-quality research is needed in the field of prevention, accurate and reliable diagnostic measures and effective treatment of CRBSI in children.

Hemodialysis catheter thrombi: visualization and quantification of microstructures and cellular composition

PURPOSE

Despite the increasing use of central venous catheters (CVC) for hemodialysis in clinical practice, the role of CVC in thrombus development is poorly understood. This work aims at defining new methods and protocols for assessing the micromorphology and composition of thrombi formed into tunneled and non-tunneled hemodialysis CVC removed from patients. 


METHODS

Twenty-nine CVCs were collected and the microscopic features of intra-luminal thrombi were quantified by scanning electron microscopy (SEM) and visualized by two photon laser scanning microscopy (TPLSM). 


RESULTS

SEM quantification showed that fibrin was the most abundant structure in CVC thrombi. Specifically, the median micromorphologic composition of the surface layer resulted in: 42.6% of fibrin plaque, 16.3% of fibrin network, 0.4% of fibrin fibers, 9.3% of platelets, 10.3% of erythrocytes and 1.7% of white blood cells. TPLSM showed that sub-surface layers were instead composed by smaller amounts of fibrin and platelets and higher amounts of blood cells.


CONCLUSIONS

Integration of SEM and TPLSM was found to be an excellent tool for characterizing thrombi in hemodialysis CVC removed from patients. Protocols and techniques presented here may be useful in the development and testing of new strategies for limiting thrombus formation on vascular access because of CVC.