Antimicrobial lock therapy in central-line associated bloodstream infections: a systematic review

Intravascular Catheter-Related Bloodstream Infections: Contemporary Issues Related to a Persistent Problem

Hospital-acquired infections, including central line associated bloodstream infections (CLABSI), are an ongoing source of cost, morbidity, and mortality worldwide. This article presents a summary of the impact of the recent SARS-CoV-2 pandemic on CLABSI incidence, an overview of current standard-of-care practices for reduction of CLABSI, and a look toward future changes in bacteremia metrics and challenges in prevention.

Medical Device-Associated Biofilm Infections and Multidrug-Resistant Pathogens

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

Antibiotic lock solutions as adjunct therapy for catheter-related blood stream infections in pediatric hemodialysis patients

The predominant use of intravenous catheters as primary access type in the pediatric hemodialysis population is associated with an increased risk of catheter related blood stream infections. While strict adherence to catheter placement and long-term care guidelines have helped to decrease the incidence of these infections, blood stream infections remain an infection burden in pediatric patients with long term hemodialysis catheters. The formation of biofilms on the surfaces of these catheters has been shown to be a source of microbes causing blood stream infections. One of the strategies for preventing bacterial colonization, inhibiting microbial multiplication, and suppressing the seeding of these microbes from biofilms upon maturation, has been the use of antibiotic-based lock solutions in-between dialysis treatments. Although clinical guidelines for the use of antibiotic lock solutions are yet to be developed, available evidence suggests a beneficial role of antibiotic lock solutions in the management of catheter related blood stream infections. Additionally, a clear understanding of how biofilms are formed and their role in the pathogenesis of catheter related bloodstream infection will facilitate the development of solutions that can prevent biofilm formation and inhibit their multiplication, maturation and seeding into the bloodstream.

Central venous catheter safety in pediatric patients with intestinal failure

Children with intestinal failure (IF) require long-term central venous access to provide life-sustaining parenteral nutrition. Mechanical, thrombotic, and infectious complications are potentially life-threatening and may necessitate central venous catheter (CVC) replacement. Repeated central line replacements may lead to a loss of vascular access sites and increases risk for intestinal transplantation. Children with IF face unique challenges for CVC safety given their young age, altered anatomy, and increased risk of thrombosis and infection. The following review addresses preventative, diagnostic, and treatment strategies for central line safety concerns specific to children with IF as well as recommendations for promoting catheter safety during activities, travel, and emergencies.

Daptomycin as an option for lock therapy: a systematic literature review

Aim: To review preclinical and clinical data relevant to daptomycin lock therapy in catheter-related bloodstream infection (CRBSI). Methods: Systematic review in PubMed, Scopus and clinical trial registries. Results: Preclinical data demonstrate daptomycin lock solution stability and compatibility with heparin, good biofilm penetration, bactericidal activity against biofilm-embedded bacteria, and high efficacy in vitro and in animal catheter infection models. Clinical data remain limited (two case reports and five case series totaling n = 65 CRBSI episodes), albeit promising (successful catheter salvage in about 80% of cases). Conclusion: Despite theoretical advantages of daptomycin, clinical data remain scarce. Comparative studies versus alternative lock solutions are needed, as well as studies to define optimal daptomycin lock regimen (including optimal concentration, dwell time and lock duration).

Effectiveness of Antimicrobial Lock Therapy for the Treatment of Catheter-Related and Central-Line-Associated Bloodstream Infections in Children: A Single Center Retrospective Study

Antimicrobial lock solutions (ALT) in combination with systemic antibiotics can represent a valid option to attempt central venous catheter (CVC) salvage in the case of catheter-related and central-line-associated bloodstream infections (CRBSI and CLABSI). However, data concerning the effectiveness and safety of ALT in children are limited. We aimed to share our center's experience in order to contribute to investigations into the causes of ALT failure in the pediatric population. All children consecutively admitted to Meyer Children's Hospital, University of Florence, Italy, from 1 April 2016 to 30 April 2022, who received salvage ALT to treat an episode of CRBSI/CLABSI, were reviewed. According to ALT failure or success, children were compared with the aim of identifying the risk factors for unsuccessful ALT outcome. Data from 28 children, 37 CLABSI/CRBSI episodes, were included. ALT was associated with clinical and microbiologic success in 67.6% (25/37) of children. No statistically significant differences were observed between the two groups, successes and failures, considering age, gender, reason for use, duration, insertion, type and presence of insertion site infection of the CVC, laboratory data and number of CRBSI episodes. Nevertheless, a trend towards a higher success rate was observed for a dwell time of 24 h for the entire duration of ALT (88%; 22/25 vs. 66.7%; 8/12; p = 0.1827), while the use of taurolidine and the infections sustained by MDR bacteria were associated with a tendency toward greater failure (25%; 3/12 vs. 4%; 1/25; p = 0.1394; 60%; 6/10 vs. 33.3%; 8/24; p = 0.2522). No adverse events, except one CVC occlusion, were observed. ALT combined with systemic antibiotics appears to be an effective and safe strategy for treating children with CLABSI/CRBSI episodes.

Chlorhexidine (di)gluconate locking device for central line infection prevention in intensive care unit patients: a multi-unit, pilot randomized controlled trial

PURPOSE

Intensive care unit (ICU) patients are at risk for central line-associated bloodstream infection (CLABSI) with significant attributable mortality and increased hospital length of stay, readmissions, and costs. Chlorhexidine (di)gluconate (CHG) is used as a disinfectant for central line insertion; however, the feasibility and efficacy of using CHG as a locking solution is unknown.

METHODS

Patients with a central venous access device (CVAD) in situ were randomized to standard care or a CHG lock solution (CHGLS) within 72 hours of ICU admission. The CHG solution was instilled in the lumen of venous catheters not actively infusing. CVAD blood cultures were taken at baseline and every 48 hours. The primary outcome was feasibility including recruitment rate, consent rate, protocol adherence, and staff uptake. Secondary outcomes included CVAD colonization, bacteraemia, and clinical endpoints.

RESULTS

Of 3,848 patients screened, 122 were eligible for the study and consent was obtained from 82.0% of the patients or substitute decision makers approached. Fifty participants were allocated to each group. Tracking logs indicated that the CHGLS was used per protocol 408 times. Most nurses felt comfortable using the CHGLS. The proportion of central line colonization was significantly higher in the standard care group with 40 (29%) versus 26 (18.7%) in the CHGLS group (P=0.009).

CONCLUSIONS

Using a device that delivers CHG into CVADs was feasible in the ICU. Findings from this trial will inform a full-scale randomized controlled trial and provide preliminary data on the effectiveness of CHGLS.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier NCT03309137, registered on October 13, 2017.

Catheter salvage strategies in children with central venous catheter related or associated bloodstream infections: a systematic review and meta-analysis

BACKGROUND

Optimal management of Central Venous Catheter related, or associated, bloodstream infections (CRBSI or CLABSI) in children is not established.

OBJECTIVE

To evaluate successful of catheter salvage strategies in pediatric patients.

METHODS

Studies retrieved from medical databases and article reference lists. Data were collected relating to clinical outcomes of 2 treatments: systemic antibiotics alone or in association with antimicrobial lock therapy (ALT). 95% CIs and OR were calculated from a mixed logistic effects model. Heterogeneity was summarized using I2 statistics. Publication bias was investigated by Egger's regression test and funnel plots.

RESULTS

From 345 identified publications, 19 met inclusion criteria (total of 914 attempted salvage strategies. To achieve successful catheter salvage, in CRBSI the addition of ALT was superior to systemic antibiotics alone (OR -0.40, 95%CI -1.41 - 0.62): 77% (95%CI 69-85, I2=42.5%, p=0.12) and 68% of success (95%CI 59-77, I2=0, p<0.05), respectively. CRBSI recurrence was less common in studies that used ALT compared with systemic antibiotics alone: 5% (95%CI 0-13, I2=59.7%; p=0.03) and 18% of recurrence (95%CI, 9-28, I2=0, p< 0.05), respectively. Recurrences were low with both antibiotic-locks and ethanol-lock. No clear benefits of ALT addition compared to systemic antibiotic only was found in CLABSI (OR -0.81, 95% CI -0.80 - 2.43).

CONCLUSIONS

The addition of an antimicrobial lock solution to systemic antibiotic may be beneficial for successful catheter salvage in pediatric patients with CRBSI, depending on etiology, whilst no statistically significant difference between systemic antibiotic with or without addition of an antimicrobial lock solution was found regarding CLABSI.

The efficacy of taurolidine containing lock solutions for the prevention of central-venous-catheter-related bloodstream infections: a systematic review and meta-analysis

The incidence of central venous catheter (CVC)-related bloodstream infections is high in patients requiring a long-term CVC. Therefore, infection prevention is of the utmost importance. The aim of this study was to provide an updated overview of randomized controlled trials (RCTs) comparing the efficacy of taurolidine containing lock solutions (TL) to other lock solutions for the prevention of CVC-related bloodstream infections in all patient populations. On 15^th February 2021, PubMed, Embase and The Cochrane Library were searched for RCTs comparing the efficacy of TLs for the prevention of CVC-related bloodstream infections with other lock solutions. Exclusion criteria were non-RCTs, studies describing <10 patients and studies using TLs as treatment. Risk of bias was evaluated using the Cochrane Risk of Bias 2 tool. A random effects model was used to pool individual study incidence rate ratios (IRRs). Subgroup analyses were performed based on the following factors: CVC indication, comparator lock and bacterial isolates cultured. A total of 14 articles were included in the qualitative synthesis describing 1219 haemodialysis, total parenteral nutrition and oncology patients. The pooled IRR estimated for all patient groups together (nine studies; 918 patients) was 0.30 (95% confidence interval 0.19-0.46), favouring the TLs. Adverse events (10 studies; 867 patients) were mild and scarce. The quality of the evidence was limited due to a high risk of bias and indirectness of evidence. The use of TLs might be promising for the prevention of CVC-related bloodstream infections. Large-scale RCTs are needed to draw firm conclusions on the efficacy of TLs.

S-Nitroso-N-acetyl-l-cysteine Ethyl Ester (SNACET) Catheter Lock Solution to Reduce Catheter-Associated Infections

Antimicrobial-lock therapy is an economically viable strategy to prevent/reduce the catheter-related bloodstream infections (CRBSI) that are associated with central venous catheters (CVCs). Herein, we report the synthesis and characterization of the S-nitroso-N-acetyl-l-cysteine ethyl ester (SNACET), a nitric oxide (NO)-releasing molecule, and for the first time its application as a catheter lock solution to combat issues of bacterial infection associated with indwelling catheters. Nitric oxide is an endogenous gasotransmitter that exhibits a wide range of biological properties, including broad-spectrum antimicrobial activity. The storage stability of the SNACET and the NO release behavior of the prepared lock solution were analyzed. SNACET lock solutions with varying concentrations exhibited tuneable NO release at physiological levels for >18 h, as measured using chemiluminescence. The SNACET lock solutions were examined for their efficacy in reducing microbial adhesion after 18 h of exposure toStaphylococcus aureus (Gram-positive bacteria) andEscherichia coli (Gram-negative bacteria). SNACET lock solutions with 50 and 75 mM concentrations were found to reduce >99% (ca. 3-log) of the adhered S. aureus and E. coli adhesion to the catheter surface after 18 h. The SNACET lock solutions were evaluated in a more challenging in vitro model to evaluate the efficacy against an established microbial infection on catheter surfaces using the same bacteria strains. A >90% reduction in viable bacteria on the catheter surfaces was observed after instilling the 75 mM SNACET lock solution within the lumen of the infected catheter for only 2 h. These findings propound that SNACET lock solution is a promising biocidal agent and demonstrate the initiation of a new platform technology for NO-releasing lock solution therapy for the inhibition and treatment of catheter-related infections.

Biofilms by bacterial human pathogens: Clinical relevance - development, composition and regulation - therapeutical strategies

Notably, bacterial biofilm formation is increasingly recognized as a passive virulence factor facilitating many infectious disease processes. In this review we will focus on bacterial biofilms formed by human pathogens and highlight their relevance for diverse diseases. Along biofilm composition and regulation emphasis is laid on the intensively studied biofilms of Vibrio cholerae, Pseudomonas aeruginosa and Staphylococcus spp., which are commonly used as biofilm model organisms and therefore contribute to our general understanding of bacterial biofilm (patho-)physiology. Finally, therapeutical intervention strategies targeting biofilms will be discussed.

Minimising Blood Stream Infection: Developing New Materials for Intravascular Catheters

Catheter related blood stream infection is an ever present hazard for those patients requiring venous access and particularly for those requiring long term medication. The implementation of more rigorous care bundles and greater adherence to aseptic techniques have yielded substantial reductions in infection rates but the latter is still far from acceptable and continues to place a heavy burden on patients and healthcare providers. While advances in engineering design and the arrival of functional materials hold considerable promise for the development of a new generation of catheters, many challenges remain. The aim of this review is to identify the issues that presently impact catheter performance and provide a critical evaluation of the design considerations that are emerging in the pursuit of these new catheter systems.

Chlorhexidine locking device for central line infection prevention in ICU patients: protocol for an open-label pilot and feasibility randomized controlled trial

Background

Critically ill patients in the intensive care unit (ICU) are at risk for central line-associated bloodstream infection (CLABSI) with an incidence up to 6.9 per 1000 catheter days. CLABSI has a significant attributable mortality and increases in-hospital length of stay, readmissions, and costs. Chlorhexidine gluconate (CHG), a broad-spectrum biocide, has been shown to effectively reduce infections including CLABSI; however, few trials have utilized CHG for prevention of central line infections. Our preclinical work has demonstrated a device that diffuses CHG into the intravenous lock solution of central venous catheters and decreases bacterial growth on the catheter lumen. We designed a clinical trial to test the feasibility of using a CHG device in an ICU patient population.

Methods

The proposed pilot trial will be a single centre, open-label, two-arm, parallel group feasibility randomized controlled trial (RCT). Participants will have a central line in situ and will be enrolled within 72 h of admittance to 3 ICUs at a single academic hospital. Exclusion criteria will include suspected infection, chronic indwelling catheters, and CHG allergy. Informed consent will be obtained from eligible participants or their substitute decision maker prior to randomization. Participants will be randomized to receive either usual care or the CHG locking device. Blood cultures will be drawn from all participants every 48 h. The primary objective of this study will be to determine the feasibility of using this protocol to conduct a larger trial. Feasibility will be assessed through the following outcomes: (1) consent rate, (2) recruitment rate, (3) protocol adherence, and (4) comfort level with the device. The secondary objective of this study will be to establish the preliminary efficacy of the device.

Discussion

This study will be the first human RCT to investigate a CHG locking device for the prevention of central line infections. Findings from this trial will inform the feasibility of conducting a large RCT and provide preliminary data on the efficacy of a CHG locking device.

Trial registration

ClinicalTrials.gov, NCT03309137, registered on October 13, 2017.

Antimicrobial Lock Therapy in Clinical Practice: A Scoping Review Protocol

Our objective is to review the scientific literature on the use of antimicrobial lock therapy (ALT). To achieve this result, our scoping review will address the following seven key questions: 1) Who are the patients who will benefit from this technique? 2) What are the techniques utilized? 3) What are the settings in which the technique is performed? 4) When the technique is performed? 5) Why the technique is performed? 6) How the technique is performed? 7) In how much amount, of such technique performed? This review considers all studies published in full and in peer-reviewed journals, with no restrictions on language, on the year of publication and age of the participants. Both randomized controlled trials and observational studies will be included. This scoping review has been planned on a five-stage framework: 1. Identifying the review question; 2. identifying relevant studies; 3. study selection; 4. charting the data; 5. collating, summarizing, and reporting the results. It is conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Guidelines. The databases utilized will include MEDLINE via PubMed, EMBASE and Cochrane Central Register of Controlled Trials and Grey Literature. SCOPING REVIEW REGISTRATION: Open Science Framework https://osf.io/vphwm/.

Antimicrobial Locks in Patients Receiving Home Parenteral Nutrition

Catheter-related bloodstream infection (CRBSI) is one of the most common and potentially fatal complications in patients receiving home parenteral nutrition (HPN). In order to prevent permanent venous access loss, catheter locking with an antimicrobial solution has received significant interest and is often a favored approach as part of the treatment of CRBSI, but mainly for its prevention. Several agents have been used for treating and preventing CRBSI, for instance antibiotics, antiseptics (ethanol, taurolidine) and, historically, anticoagulants such as heparin. Nonetheless, current guidelines do not provide clear guidance on the use of catheter locks. Therefore, this review aims to provide a better understanding of the current use of antimicrobial locking in patients on HPN as well as reviewing the available data on novel compounds. Despite the fact that our current knowledge on catheter locking is still hampered by several gaps, taurolidine and ethanol solutions seem promising for prevention and potentially, but not proven, treatment of CRBSI. Additional studies are warranted to further characterize the efficacy and safety of these agents.

Is heparinized 40% ethanol lock solution efficient for reducing bacterial and fungal biofilms in an in vitro model?

Background

We applied an in vitro model to evaluate the efficacy of a heparinized 40% ethanol-based lock solution in a wide variety of clinical isolates causing C-RBSI.

Methods

A total of 100 clinical strains were collected retrospectively from the blood of patients with C-RBSI. The reduction in biomass and metabolic activity of biofilms was measured using the crystal violet (CV) assay and XTT assay, respectively. Regrowth inhibition (RI) was measured within 24 hours and 72 hours of ethanol lock therapy. Percentage reduction of ≥ 85% in RI was considered to be successful.

Results

Ethanol lock was more effective in reducing metabolic activity than in reducing biomass (83% vs. 50%, respectively). Percentages of RI diminished as regrowth was prolonged (57% for 24 hours and 17% for 72 hours of regrowth). No statistically significant intraspecies differences were found in biofilm reduction or in RI (p>0.05).

Conclusions

The use of heparinized 40% ethanol lock solution for 72 hours significantly reduced biomass and metabolic activity in clinical isolates from patients with C-RBSI. However, as biofilm has an important regrowth rate, 40% ethanol solution was not able to fully eradicate biofilm in vitro.

Dose-Dependent Synergistic Interactions of Colistin with Rifampin, Meropenem, and Tigecycline against Carbapenem-Resistant Klebsiella pneumoniae Biofilms

Carbapenem-resistant Klebsiella pneumoniae (CR-Kp) can cause biofilm-related bloodstream infections associated with significant morbidity and mortality worldwide. We investigated the bactericidal activities of colistin (CST), rifampin (RIF), meropenem (MEM), gentamicin (GEN), and tigecycline (TGC) alone and that of CST in combination with RIF, MEM, GEN, or TGC against CR-Kp mature biofilms. Twenty CR-Kp blood isolates were derived from an equal number of bloodstream infections in adult patients. Biofilm formation was assessed by staining with 0.4% crystal violet and measuring the optical density spectrophotometrically at 545 nm. Biofilm damage was measured as the percent reduction of metabolic activity by an XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide salt] assay. The MIC₅₀ for biofilms was determined as the minimum concentration that caused ≥50% bacterial damage compared to that for untreated controls. Antibacterial drug interactions were analyzed by the Bliss independence model. Four of the 20 CR-Kp isolates were biofilm producers. Biofilm MIC₅₀s of CST, RIF, MEM, GEN, and TGC for these isolates were 64, 8, >256, 128, and 8 mg/liter, respectively. Synergistic interactions were observed at 32 to 64 mg/liter of CST combined with 0.25 to 4 mg/liter of RIF, at 32 mg/liter of CST combined with 0.007 to 0.25 mg/liter of MEM, and at 16 to 32 mg/liter of CST combined with 16 to 64 mg/liter of TGC. The synergy was highest for CST plus RIF, with a mean ΔE ± standard error (SE) of 49.87% ± 9.22%, compared to 29.52% ± 4.97% for CST plus MEM (P < 0.001) and 32.44% ± 6.49% for CST plus TGC (P < 0.001). Indifferent results were exhibited by CST plus GEN. None of the combinations exhibited antagonism. These drug interaction findings, especially those for CST with RIF, may be of importance in the treatment of biofilm-related CR-Kp infections.

Antimicrobial Efficacy and Safety of a Novel Gas Plasma-Activated Catheter Lock Solution

Antimicrobial lock solutions are important for prevention of microbial colonization and infection of long-term central venous catheters. We investigated the efficacy and safety of a novel antibiotic-free lock solution formed from gas plasma-activated disinfectant (PAD). Using a luminal biofilm model, viable cells of methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Candida albicans in mature biofilms were reduced by 6 to 8 orders of magnitude with a PAD lock for 60 min. Subsequent 24-h incubation of PAD-treated samples resulted in no detectable regrowth of viable bacteria or fungi. As a comparison, the use of a minocycline-EDTA-ethanol lock solution for 60 min led to regrowth of bacteria and fungi, up to 10⁷ to 10⁹ CFU/ml, in 24 h. The PAD lock solution had minimal impact on human umbilical vein endothelial cell viability, whereas the minocycline-EDTA-ethanol solution elicited cell death in nearly half of human endothelial cells. Additionally, PAD treatment caused little topological change to catheter materials. In conclusion, PAD represents a novel antibiotic-free, noncytotoxic lock solution that elicits rapid and broad-spectrum eradication of biofilm-laden microbes and shows promise for the prevention and treatment of intravascular catheter infections.

Ethanol locks for the prevention of catheter-related bloodstream infection: a meta-analysis of randomized control trials

Background

Current evidence regarding the efficacy of ethanol locks in preventing catheter-related bloodstream infection (CRBI) is inconclusive.

Methods

Electronic databases, including PubMed, Web of Science, Embase, and the Cochrane Library (until April 2018),were systematically searched for relevant studies. Two reviewers independently screened the retrieved records and identified RCTs that met the inclusion criteria. Relevant data were extracted for pooled analyses using Review Manager 5.3 software. Subgroup analysis was performed according to the study quality, duration of the ethanol lock, disease type and CRBI definition. Eggs’ method was applied to detect publication bias. Sensitivity analysis was conducted to check the stability of the meta-analysis results.

Results

Ten RCTs involving 2760 patients were included in the analysis. The overall pooled result indicated that ethanol locks significantly reduced the incidence of CRBI (RR 0.66, 95% CI 0.51–0.86). Subgroup analysis suggested that an ethanol lock significantly decreased the incidence of CRBI in patients with hematological diseases (RR 0.50, 95% CI 0.31–0.80). An ethanol lock significantly reduced the incidence of CRBI in a2-hour ethanol lock group (RR 0.49, 95% CI 0.33–0.73). The meta-analysis showed that an ethanol lock significantly reduced the incidence of CRBI according to analysis of high-(RR 0.66, 95% CI 0.47–0.94) or low-(RR 0.66, 95% CI 0.46–0.95) quality studies. Meta-analysis of studies with a strict CRBI definition showed that an ethanol lock can significantly prevent CRBI (RR 0.61, 95% CI 0.42–0.89). The results of sensitivity analysis suggested that the pooled result was stable. Meta-analysis of adverse events showed that an ethanol lock did not increase the incidence of thrombosis (RR 1.05, 95% CI 0.51–2.18) or mortality (RR 0.99, 95% CI 0.90–1.08) but did result in increased nausea (RR 1.54, 95% CI 1.01–2.35), dizziness (RR 4.21, 95% CI 2.40–7.39),elevated blushing rates (RR 3.27, 95% CI 2.05–5.22) and altered taste rates (RR 2.61, 95% CI 1.93–3.54).

Conclusions

An ethanol lock may play a role in the prevention of CRBI, especially in immunocompromised patients with hematological diseases.

Electronic supplementary material

The online version of this article (10.1186/s12871-018-0548-y) contains supplementary material, which is available to authorized users.

Living Donor Intestinal Transplantation

Living donor intestinal transplantation (LDIT) has been improved leading to results comparable to those obtained with deceased donors. LDIT should be limited to specific indications and patient selection. The best indication is combined living donor intestinal/liver transplantation in pediatric recipients with intestinal and hepatic failure; the virtual elimination of waiting time may avoid the high mortality experienced by candidates on the deceased waiting list. Potentially, LDIT could be used in highly sensitized recipients to allow the application of de-sensitization protocols. In the case of available identical twins or HLA-identical sibling, LDIT has a significant immunologic advantage and should be offered.

The optimal ethanol lock therapy regimen for treatment of biofilm-associated catheter infections: an in-vitro study

BACKGROUND

Ethanol-based lock therapy (LT) solutions are used as an alternative to antibiotics for the conservative management of catheter-related bloodstream infection. However, no clear consensus on regimen or dose has been reached.

AIM

To find the ethanol-based lock solution containing a sufficiently low concentration of ethanol for reduction of the metabolic activity of bacterial and fungal biofilms.

METHODS

Using an in-vitro model, three concentrations of ethanol (25%, 40%, 70%) were tested, with and without 60 IU of heparin, at six different time-points and against 24 h preformed biofilms of Staphylococcus aureus ATCC29213, Staphylococcus epidermidis (clinical isolate), Enterococcus faecalis ATCC33186, Candida albicans ATCC14058, and Escherichia coli ATCC25922. The reduction in the metabolic activity of the biofilm was measured using the tetrazolium salt assay and LT was considered to be successful when metabolic activity fell by >90%. Regrowth inhibition was then tested within 24 h and seven days after each LT regimen only at the ethanol concentration of the most successful LT regimen.

FINDINGS

The most successful LT was achieved with 40% ethanol + 60 IU of heparin only at 24, 72, and 24 h for seven-day regimens (P < 0.05). However, none of the regimens reached 45% RI within seven days of therapy.

CONCLUSION

According to our in-vitro data, an ethanol-based lock solution with 40% ethanol + 60 IU heparin administered daily for 72 h is sufficient to almost eradicate the metabolic activity of bacterial and fungal biofilms. Future studies are needed to study cell regrowth after LT.

Microbial Biofilms in Pulmonary and Critical Care Diseases

Microbial biofilms can colonize medical devices and human tissues, and their role in microbial pathogenesis is now well established. Not only are biofilms ubiquitous in natural and human-made environments, but they are also estimated to be associated with approximately two-thirds of nosocomial infections. This multicellular aggregated form of microbial growth confers a remarkable resistance to killing by antimicrobials and host defenses, leading biofilms to cause a wide range of subacute or chronic infections that are difficult to eradicate. We have gained tremendous knowledge on the molecular, genetic, microbiological, and biophysical processes involved in biofilm formation. These insights now shape our understanding, diagnosis, and management of many infectious diseases and direct the development of novel antimicrobial therapies that target biofilms. Bacterial and fungal biofilms play an important role in a range of diseases in pulmonary and critical care medicine, most importantly catheter-associated infections, ventilator-associated pneumonia, chronic Pseudomonas aeruginosa infections in cystic fibrosis lung disease, and Aspergillus fumigatus pulmonary infections.

Pre-emptive Intestinal Transplant: The Surgeon's Point of View

Pre-emptive transplantation is a well-established practice for certain types of end-organ failure such as in the use of kidney transplantation. For irreversible intestinal failure, total parenteral nutrition (TPN) remains the gold standard, due to the suboptimal long-term results of intestinal transplantation. As such, the only role for pre-emptive transplantation, if at all, will be for patients identified to be at high risk of complications and mortality while on definitive long-term TPN. In these patients, the timing of early listing and transplantation could become life-saving, taking into account that mortality on the waiting list is still the highest for intestinal candidates. The development of simulation models or pre-transplant scoring systems could help in selecting patients based on potential outcome on TPN or with transplantation, and recent reports from high-volume centers identify few underlying pathologic conditions and some TPN complications as at higher risk of increased morbidity and mortality. A pre-emptive transplant could be used as a rehabilitative procedure in a well-selected case-by-case scenario, among TPN patients at risk of liver failure, repeated central line infections, mesenteric infarction, short bowel syndrome (SBS) <50 cm or with end stoma, congenital mucosal disease, desmoid tumors: These conditions must be carefully evaluated, not to underestimate the clinical stage nor to over-estimate the impact of a temporary situation. At the present time, diseases with a variable and unpredictable course, such as intestinal dysmotility disorders, or quality of life and financial issues are still far from being considered as indications for a pre-emptive transplant.

Toxin Mediates Sepsis Caused by Methicillin-Resistant Staphylococcus epidermidis

Bacterial sepsis is a major killer in hospitalized patients. Coagulase-negative staphylococci (CNS) with the leading species Staphylococcus epidermidis are the most frequent causes of nosocomial sepsis, with most infectious isolates being methicillin-resistant. However, which bacterial factors underlie the pathogenesis of CNS sepsis is unknown. While it has been commonly believed that invariant structures on the surface of CNS trigger sepsis by causing an over-reaction of the immune system, we show here that sepsis caused by methicillin-resistant S. epidermidis is to a large extent mediated by the methicillin resistance island-encoded peptide toxin, PSM-mec. PSM-mec contributed to bacterial survival in whole human blood and resistance to neutrophil-mediated killing, and caused significantly increased mortality and cytokine expression in a mouse sepsis model. Furthermore, we show that the PSM-mec peptide itself, rather than the regulatory RNA in which its gene is embedded, is responsible for the observed virulence phenotype. This finding is of particular importance given the contrasting roles of the psm-mec locus that have been reported in S. aureus strains, inasmuch as our findings suggest that the psm-mec locus may exert effects in the background of S. aureus strains that differ from its original role in the CNS environment due to originally “unintended” interferences. Notably, while toxins have never been clearly implied in CNS infections, our tissue culture and mouse infection model data indicate that an important type of infection caused by the predominant CNS species is mediated to a large extent by a toxin. These findings suggest that CNS infections may be amenable to virulence-targeted drug development approaches.

Coagulase-negative staphylococci (CNS) are the leading cause of sepsis in hospitalized patients, causing a significant number of deaths. This situation is further worsened by a limitation of therapeutic options due to the fact that most CNS infectious isolates are resistant to methicillin. CNS sepsis has been assumed to be due to on over-reacting immune response triggered by invariant bacterial surface structures. By using tissue culture and animal infection model-based evidence, we here show that in contrast to that notion, the PSM-mec toxin produced by methicillin-resistant strains of the leading CNS species Staphylococcus epidermidis has a strong impact on the severity of sepsis and its outcome. This is the first report to link a toxin to the pathogenesis of the most frequent bacterial cause of sepsis. Notably, these findings pave the way for anti-virulence strategies against this widespread and deadly type of infection.

Are antimicrobial peripherally inserted central catheters associated with reduction in central line-associated bloodstream infection? A systematic review and meta-analysis

BACKGROUND

Antimicrobial peripherally inserted central catheters (PICCs) may reduce the risk of central line-associated bloodstream infection (CLABSI). However, data regarding efficacy are limited. We aimed to evaluate whether antimicrobial PICCs are associated with CLABSI reduction.

METHODS

MEDLINE, EMBASE, CINHAL, and Web of Science were searched from inception to July 2016; conference proceedings were searched to identify additional studies. Study selection and data extraction were performed independently by 2 authors.

RESULTS

Of 597 citations identified, 8 studies involving 12,879 patients met eligibility criteria. Studies included adult and pediatric patients from intensive care, long-term care, and general ward settings. The incidence of CLABSI in patients with antimicrobial PICCs was 0.2% (95% confidence interval [CI], 0.0%-0.5%), and the incidence among nonantimicrobial catheters was 5.3% (95% CI, 2.6%-8.8%). Compared with noncoated PICCs, antimicrobial PICCs were associated with a significant reduction in CLABSI (relative risk [RR], 0.29; 95% CI, 0.10-0.78). Statistical heterogeneity (I², 71.6%; T2 = 1.07) was resolved by publication type, with peer-reviewed articles showing greater reduction in CLABSI (RR, 0.21; 95% CI, 0.06-0.74). Twenty-six patients (95% CI, 21-75) need to be treated with antimicrobial PICCs to prevent 1 CLABSI. Studies of adults at greater baseline risk of CLABSI experienced greater reduction in CLABSI (RR, 0.20; P = .003).

CONCLUSIONS

Available evidence suggests that antimicrobial PICCs may reduce CLABSI, especially in high-risk subgroups. Randomized trials are needed to assess efficacy across patient populations.

Surveillance of bloodstream infections in pediatric cancer centers - what have we learned and how do we move on?

Pediatric patients receiving conventional chemotherapy for malignant disease face an increased risk of bloodstream infection (BSI). Since BSI may represent an acute life-threatening event in patients with profound immunosuppression, and show further negative impact on quality of life and anticancer treatment, the prevention of BSI is of paramount importance to improve and guarantee patients' safety during intensive treatment. The great majority of all pediatric cancer patients (about 85%) have a long-term central venous access catheter in use (type Broviac or Port; CVAD). Referring to the current surveillance definitions a significant proportion of all BSI in pediatric patients with febrile neutropenia is categorized as CVAD-associated BSI. This state of the art review summarizes the epidemiology and the distinct pathogen profile of BSI in pediatric cancer patients from the perspective of infection surveillance. Problems in executing the current surveillance definition in this patient population are discussed and a new concept for the surveillance of BSI in pediatric cancer patients is outlined.

Effect of caspofungin and micafungin in combination with farnesol against Candida parapsilosis biofilms

The in vitro activities of caspofungin and micafungin were determined with and without farnesol against Candida parapsilosis biofilms. Drug interactions were examined using the XTT colorimetric assay-based broth microdilution chequerboard method. Drug-drug interactions were assessed utilising the FICI, Bliss independence models and time-kill experiments. Median sessile MICs of five C. parapsilosis clinical isolates ranged between 32-256 mg/L, 16-512 mg/L and >300 μM for caspofungin, micafungin and farnesol, respectively. Median MICs for caspofungin and micafungin in combination with farnesol showed 8-64- and 4-64-fold decreases, respectively. Paradoxical growth noticed with both echinocandins was eliminated by farnesol. Based on FICIs for sessile clinical isolates, synergism was observed for caspofungin (range of median FICIs, 0.155-0.5) and micafungin (range of median FICIs, 0.093-0.5). Concordantly, MacSynergy analysis and global fitting of non-linear regression based on a Bliss independence models also showed synergism for caspofungin and micafungin. In line with FICI findings and the Bliss independence model, synergistic interactions were confirmed by time-kill experiments. The metabolic activity of fungal cells was significantly inhibited by caspofungin+farnesol at all three tested combinations (4 mg/L+75 μM, 8 mg/L+75 μM and 16 mg/L+75 μM) between 3 and 24 h compared with the control (P<0.05-0.001). Significant inhibition was observed for micafungin+farnesol between 3 and 12h (P<0.001) but not at 24 h. Despite the favourable effect of farnesol in combination with echinocandins, further in vivo studies are needed to confirm its therapeutic advantage in catheter-associated infections caused by C. parapsilosis.

Total Parenteral Nutrition-Induced Cholestasis: Prevention and Management

When cholestasis occurs in patients receiving total parenteral nutrition, it is the result of many pathogenic pathways converging on the hepatic acinus. The result may be a temporary rise in liver function tests. The resulting fibrosis, portal hypertension, and jaundice are hallmarks of type 3 intestinal-associated liver disease to which children are more susceptible than adults. The key to prevention is in identifying high-risk scenarios, meticulous monitoring, and personalized prescription of parenteral nutrition solutions combined with an active approach in reducing the impact of inflammatory events when they occur by prompt use of antibiotics and line locks.

Evidence-Based Criteria for the Choice and the Clinical use of the Most Appropriate Lock Solutions for Central Venous Catheters (Excluding Dialysis Catheters): A GAVeCeLT Consensus

Background

The most appropriate lock solution for central venous access devices is still to be defined. GAVeCeLT – the Italian group for venous access devices – has developed a consensus on the evidence-based criteria for the choice and the clinical use of the most appropriate lock solution for central venous catheters (excluding dialysis catheters).

Method

After the constitution of a panel of experts, a systematic collection and review of the literature has been performed, focusing on clinical studies dealing with lock solutions used for prevention of occlusion (heparin, citrate, urokinase, recombinant tissue plasminogen activator [r-TPA], normal saline) or for prevention of infection (citrate, ethanol, taurolidine, ethylene-diamine-tetra-acetic acid [EDTA], vancomycin, linezolid and other antibiotics), in both adults and in pediatric patients. Studies on central lines used for dialysis or pheresis, on peripheral venous lines and on arterial lines were excluded from this analysis. Studies on lock solutions used for treatment of obstruction or infection were not considered. The consensus has been carried out according to the Delphi method.

Results

The panel has concluded that: (a) there is no evidence supporting the heparin lock; (b) the prevention of occlusion is based on the proper flushing and locking technique with normal saline; (c) the most appropriate lock solution for infection prevention should include citrate and/or taurolidine, which have both anti-bacterial and anti-biofilm activity, with negligible undesired effects if compared to antibiotics; (d) the patient populations most likely to benefit from citrate/taurolidine lock are yet to be defined.

Conclusions

The actual value of heparinization for non-dialysis catheters should be reconsidered. Also, the use of lock with substances with anti-bacterial and anti-biofilm activity (such as citrate or taurolidine) should be taken into consideration in selected populations of patients.

Tigecycline Lock Therapy for Catheter-Related Bloodstream Infection Caused by KPC-Producing Klebsiella pneumoniae in Two Pediatric Hematological Patients

Catheter-related bacteremias carry high mortality rates in hematological patients. When a multidrug-resistant microorganism is involved, the catheter should ideally be removed; however, this approach is not always possible. Tigecycline lock therapy was used in two pediatric oncohematological patients with intravascular catheter-related infection due to KPC-producing Klebsiella pneumoniae. The catheter was salvaged in both cases, and the patients were later discharged. Our experience suggests the usefulness of this approach in treating this type of infection.