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

Ethanol Lock for Prevention of CVC-Related Bloodstream Infection in Pediatric Patients: A Systematic Review and Meta-Analysis

Ethanol lock therapy (ELT) can be used in patients with an indwelling central line to assist in the prevention of central venous catheter (CVC)-associated infections. However, its efficacy has not been consistently demonstrated in the pediatric population. The primary objective of this review and meta-analysis was to determine the efficacy and safety of ELT in prevention of central line-associated bloodstream infection (CLABSI) in the pediatric population. A search was conducted with the PubMed, CINAHL, PSCYInfo, Cochrane Library, and Academic Search Premier databases from inception through January 21, 2022. Studies were included if they reported incidence of CVC-related infections with ELT in pediatric patients. Meta-analyses used random-effects models according to the heterogeneity of all included studies. Of 736 studies, 25 met inclusion criteria for review and 10 for inclusion in the meta-analysis. Meta-analysis with pre- and post-ELT treatment showed that use of ELT significantly decreased mean CVC-related infections when compared with pre-treatment with no ELT with a mean difference of -5.79 (95% CI, -9.08 to -2.51; p < 0.001). The number of CVC infections also significantly decreased (OR, 0.42; 95% CI, 0.23-0.75; p = 0.004). Increased risk of thrombosis and increased frequency of catheter breakage, repair, and replacement were noted in several studies. Ethanol lock therapy is effective in preventing infection related to central venous catheter use in pediatric patients. Further study is warranted to determine the optimal protocol for, and incidence of, adverse events related to use of ELT.

Nanoparticle-Based Photodynamic Inhibition of Candida albicans Biofilms with Interfering Quorum Sensing

Biofilm formation is a critical event in the pathogenesis and virulence of fungal infections caused by Candida albicans, giving rise to about a 1000-fold increase in the resistance to antifungal agents. Although photodynamic treatment (PDT) has been excellently implicated in bacterial infections, studies on its potential against fungal infection through the clearance of fungal biofilm formation remain at its infancy stage. Here, we have designed photodynamic nanoparticles with different sizes, modifications, and the ability of generating reactive oxygen species (ROS) to examine their effects on inhibiting biofilm formation and destructing mature biofilms of C. albicans. We found that the nanoparticles modified with oligo-chitosan exhibited a better binding efficiency for planktonic cells, leading to stronger inhibitory efficacy of the filamentation and the early-stage biofilm formation. However, for mature biofilms, the nanoparticles with the smallest size (∼15 nm) showed the fastest penetration speed and a pronounced destructing effect albeit conferring the lowest ROS-producing capability. The inhibitory effect of photodynamic nanoparticles was dependent on the disruption of fungal quorum sensing (QS) by the upregulation of QS molecules, farnesol and tyrosol, mediated through the upregulation of ARO 8 and DPP 3 expression. Our findings provide a powerful strategy of nanoparticulate PDT to combat fungal infections through the inhibition of both hyphal and biofilm formation by disrupting QS.

The Current Knowledge on the Pathogenesis of Tissue and Medical Device-Related Biofilm Infections

Biofilm is the trigger for the majority of infections caused by the ability of microorganisms to adhere to tissues and medical devices. Microbial cells embedded in the biofilm matrix are highly tolerant to antimicrobials and escape the host immune system. Thus, the refractory nature of biofilm-related infections (BRIs) still represents a great challenge for physicians and is a serious health threat worldwide. Despite its importance, the microbiological diagnosis of a BRI is still difficult and not routinely assessed in clinical microbiology. Moreover, biofilm bacteria are up to 100–1000 times less susceptible to antibiotics than their planktonic counterpart. Consequently, conventional antibiograms might not be representative of the bacterial drug susceptibility in vivo. The timely recognition of a BRI is a crucial step to directing the most appropriate biofilm-targeted antimicrobial strategy.

Antifungal lock therapy: an eternal promise or an effective alternative therapeutic approach?

Each year, millions of central venous catheter insertions are performed in intensive care units worldwide. The usage of these indwelling devices is associated with a high risk of bacterial and fungal colonization, leading to the development of microbial consortia, namely biofilms. These sessile structures provide fungal cells with resistance to the majority of antifungals, environmental stress and host immune responses. Based on different guidelines, colonized/infected catheters should be removed and changed immediately in the case of Candida‐related central line infections. However, catheter replacement is not feasible for all patient populations. An alternative therapeutic approach may be antifungal lock therapy, which has received high interest, especially in the last decade. This review summarizes the published Candida‐related in vitro, in vivo data and case studies in terms of antifungal lock therapy. The number of clinical studies remains limited and further studies are needed for safe implementation of the antifungal lock therapy into clinical practice.

Factors predicting efficacy of ethanol lock therapy as catheter salvage strategy for pediatric catheter-related infections

AIM

Catheter-related infections are difficult to cure, and failure rates are high. We aimed to evaluate the efficacy and safety of ethanol lock therapy (ELT) as catheter salvage strategy in children with central-line-associated bloodstream infection (CLABSI), and to identify factors associated with treatment failure.

METHODS

Data were collected of all the children who received ELT for treatment of CLABSI during 2013-2018 due to failure of standard therapy or multiple catheter-related infections. Univariate and multivariate analyses of risk-factors for ELT failure were performed. Catheter salvage rates were compared to those achieved using systemic antimicrobials alone in an historical control group.

RESULTS

A total of 123 ELT episodes among 95 patients were analyzed. The majority of patients had underlying hemato-oncological disorders. Approximately half the episodes occurred in patients with implantable ports. Early and late treatment failure rates of ELT were 16% (20/123) and 7% (9/123), respectively. Overall, successful catheter salvage was achieved in 78% (96/123) of episodes, compared to 54% using systemic antimicrobials alone (P < .001), including mycobacterium, candida, and most staphylococcus aureus infections. Adverse events were reported in 9% (11/123) of episodes and were mostly mechanical. Multivariate analysis identified four risk factors for ELT failure: Gram-positive bacteria, elevated C-reactive protein, signs of tunnel infection, and low absolute neutrophil counts.

CONCLUSIONS

Our findings support the use of ELT for catheter salvage in children with CLABSI who failed standard therapy or had multiple catheter-related infections. The identified variables associated with ELT failure may help identify patients who can most benefit from ELT.

Mechanistic Understanding of Candida albicans Biofilm Formation and Approaches for Its Inhibition

In recent years, the demand for novel antifungal therapies has increased several- folds due to its potential to treat severe biofilm-associated infections. Biofilms are made by the sessile microorganisms attached to the abiotic or biotic surfaces, enclosed in a matrix of exopolymeric substances. This results in new phenotypic characteristics and intrinsic resistance from both host immune response and antimicrobial drugs. Candida albicans biofilm is a complex association of hyphal cells that are associated with both abiotic and animal tissues. It is an invasive fungal infection and acts as an important virulent factor. The challenges linked with biofilm-associated diseases have urged scientists to uncover the factors responsible for the formation and maturation of biofilm. Several strategies have been developed that could be adopted to eradicate biofilm-associated infections. This article presents an overview of the role of C. albicans biofilm in its pathogenicity, challenges it poses and threats associated with its formation. Further, it discusses strategies that are currently available or under development targeting prostaglandins, quorum-sensing, changing surface properties of biomedical devices, natural scaffolds, and small molecule-based chemical approaches to combat the threat of C. albicans biofilm. This review also highlights the recent developments in finding ways to increase the penetration of drugs into the extracellular matrix of biofilm using different nanomaterials against C. albicans.

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.