Faecium Infections Research Articles

Polidocanol inhibits Enterococcus faecalis virulence factors by targeting fsr quorum sensing system

BackgroundThe wide spread of antimicrobial resistance in Enterococcus faecalis is a critical global concern, leading to increasingly limited treatment options. The fsr quorum sensing (QS) plays a critical role in the pathogenicity of E. faecalis, allowing bacteria to coordinate gene expression and regulate many virulence factors. Therefore, fsr QS of E. faecalis represents a potential therapeutic target that provides an effective strategy to treat antibiotic-resistant infections induced by E. faecalis.MethodsIn this study, distribution of different virulence factors including, gelatinase, protease, cell surface hydrophobicity and biofilm formation in sixty clinical isolates of Enterococcus faecalis was investigated. Sixty-six compounds were tested for their activity against fsr QS. The minimal inhibitory concentration of the tested compounds was evaluated using the microbroth dilution method. The effect of sub-inhibitory concentrations of the tested compounds on fsr QS was investigated using the gelatinase assay method. Additionally, the effect of potential QS inhibitor on the virulence factors was estimated. Quantitative real-time PCR was used to investigate the effect of the potential inhibitor on fsr QS related genes (fsrB-fsrC) and (gelE-sprE) and virulence associated genes including, asa1 and epbA.ResultsThe assessment of polidocanol activity against the fsr QS system was demonstrated by studying its effect on gelatinase production in E. faecalis clinical isolates. Sub-lethal concentrations of polidocanol showed a significant reduction in gelatinase and protease production by 54% to 70% and 64% to 85%, respectively. Additionally, it significantly reduced biofilm formation (P < 0.01) and interrupted mature biofilm at concentrations of ½, 1 × and 2 × MIC. Furthermore, polidocanol significantly decreased cell surface hydrophobicity (P < 0.01). Polidocanol at ½ MIC showed a significant reduction in the expression of QS genes including fsrB, fsrC, gelE and sprE by 57% to 97% without affecting bacterial viability. Moreover, it reduced the expression of virulence associated genes (asa1 and epbA) (P < 0.01).ConclusionPolidocanol appears to be a promising option for treating of E. faecalis infections by targeting the fsr QS system and exhibiting anti-biofilm activity.

Investigating Sortase A inhibitory potential of herbal compounds using integrated computational and biochemical approaches

Multi-drug resistance in bacteria is emerging as a major global health challenge, causing substantial harm in terms of mortality, morbidity, and financial strain on healthcare systems. These bacteria are constantly acquiring new virulence factors and drug-resistance mechanisms, which highlights the critical need for innovative antimicrobial medicines and identification of new therapeutic targets, such as Sortase A (EfSrtAΔN59). EfSrtAΔN59, a transpeptidase significant for the adhesion and virulence of Enterococcus faecalis (E. faecalis), presents an attractive target for disrupting biofilm formation—a key factor in persistent infections. This study investigates the inhibitory effects of two natural flavonoids- Rutin Trihydrate and Quercetin, on EfSrtAΔN59 and biofilm formation in E. faecalis. With in vitro enzymatic assays and biofilm quantification techniques, we demonstrate that both compounds significantly attenuate EfSrtAΔN59 activity, thereby hindering bacterial biofilm formation. Rutin Trihydrate and Quercetin exhibited strong binding affinities to the EfSrtAΔN59 enzyme, as confirmed by molecular docking and MD simulation studies. This was further substantiated by a notable reduction in biofilm biomass in bacterial cultures treated with these compounds. These findings highlight the potential of Rutin Trihydrate and Quercetin as promising candidates for the development of novel anti-virulence therapies aimed at mitigating E. faecalis infections, thereby offering a compelling alternative to traditional antibiotics.

Characterization of Two Novel Endolysins from Bacteriophage PEF1 and Evaluation of Their Combined Effects on the Control of Enterococcus faecalis Planktonic and Biofilm Cells.

Endolysin, a bacteriophage-derived lytic enzyme, has emerged as a promising alternative antimicrobial agent against rising multidrug-resistant bacterial infections. Two novel endolysins LysPEF1-1 and LysPEF1-2 derived from Enterococcus phage PEF1 were cloned and overexpressed in Escherichia coli to test their antimicrobial efficacy against multidrug-resistant E. faecalis strains and their biofilms. LysPEF1-1 comprises an enzymatically active domain and a cell-wall-binding domain originating from the NLPC-P60 and SH3 superfamilies, while LysPEF1-2 contains a putative peptidoglycan recognition domain that belongs to the PGRP superfamily. LysPEF1-1 was active against 89.86% (62/69) of Enterococcus spp. tested, displaying a wider antibacterial spectrum than phage PEF1. Moreover, two endolysins demonstrated lytic activity against additional gram-positive and gram-negative species pretreated with chloroform. LysPEF1-1 showed higher activity against multidrug-resistant E. faecalis strain E5 than LysPEF1-2. The combination of two endolysins effectively reduced planktonic cells of E5 in broth and was more efficient at inhibiting biofilm formation and removing biofilm cells of E. faecalis JCM 7783T than used individually. Especially at 4 °C, they reduced viable biofilm cells by 4.5 log after 2 h of treatment on glass slide surfaces. The results suggest that two novel endolysins could be alternative antimicrobial agents for controlling E. faecalis infections.

Clinical characteristics, predisposing factors and outcomes for Enterococcus faecalis versus Enterococcus faecium bloodstream infections: a prospective multicentre cohort study

PurposesEnterococcal BSI is associated with significant morbidity and mortality, with fatality rates of approximately 20–30%. There are microbiological and clinical differences between E. faecalis and E. faecium infections. The aim of this study was to investigate differences in predisposing factors for E. faecalis and E. faecium BSI and to explore prognostic factors.MethodsThis study was a post-hoc analysis of PROBAC, a Spanish prospective, multicenter, cohort in 2016–2017. Patients with E. faecalis or E. faecium BSI were eligible. Independent predictors for BSI development in polymicrobial and monomicrobial BSI and in-hospital mortality in the monomicrobial group were identified by logistic regression.ResultsA total of 431 patients were included. Independent factors associated with E. faecium BSI were previous use of penicillins (aOR 1.99 (95% CI 1.20–3.32)) or carbapenems (2.35 (1.12–4.93)), hospital-acquired BSI (2.58 (1.61–4.12)), and biliary tract source (3.36 (1.84–6.13)), while congestive heart failure (0.51 (0.27–0.97)), cerebrovascular disease (0.45 (0.21–0.98)), and urinary tract source (0.49 (0.26–0.92)) were associated with E. faecalis BSI. Independent prognostic factors for in-hospital mortality in E. faecalis BSI were Charlson Comorbidity Index (1.27 (1.08–1.51)), SOFA score (1.47 (1.24–1.73)), age (1.06 (1.02–1.10)), and urinary/biliary source (0.29 (0.09–0.90)). For E. faecium BSI, only SOFA score (1.34 (1.14–1.58) was associated with in-hospital mortality.ConclusionsThe factors associated with E. faecium and E. faecalis BSI are different. These variables may be helpful in the suspicion of one or other species for empiric therapeutic decisions and provide valuable information on prognosis.

Enterococcus Phage vB_EfaS_HEf13 as an Anti-Biofilm Agent Against Enterococcus faecalis.

Enterococcus faecalis is a Gram-positive bacterium that is frequently found in the periapical lesion of patients with apical periodontitis. Its biofilm formation in root canal is closely related to the development of refractory apical periodontitis by providing increased resistance to endodontic treatments. Phage therapy has recently been considered as an efficient therapeutic strategy in controlling various periodontal pathogens. We previously demonstrated the bactericidal capacities of Enterococcus phage vB_EfaS_HEf13 (phage HEf13) against clinically-isolated E. faecalis strains. Here, we investigated whether phage HEf13 affects biofilm formation and pre-formed biofilm of clinically-isolated E. faecalis, and its combinatory effect with endodontic treatments, including chlorhexidine (CHX) and penicillin. The phage HEf13 inhibited biofilm formation and disrupted pre-formed biofilms of E. faecalis in a dose- and time-dependent manner. Interestingly, phage HEf13 destroyed E. faecalis biofilm exopolysaccharide (EPS), which is known to be a major component of bacterial biofilm. Furthermore, combined treatment of phage HEf13 with CHX or penicillin more potently inhibited biofilm formation and disrupted pre-formed biofilm than either treatment alone. Confocal laser scanning microscopic examination demonstrated that these additive effects of the combination treatments on disruption of pre-formed biofilm are mediated by relatively enhanced reduction in thickness distribution and biomass of biofilm. Collectively, our results suggest that the effect of phage HEf13 on E. faecalis biofilm is mediated by its EPS-degrading property, and its combination with endodontic treatments more potently suppresses E. faecalis biofilm, implying that phage HEf13 has potential to be used as a combination therapy against E. faecalis infections.

Trends in infection incidence and antimicrobial resistance in the US Veterans Affairs Healthcare System: a nationwide retrospective cohort study (2007–22)

Antimicrobial resistance poses a major threat to public health. There are few comprehensive nationwide studies that quantify long-term trends in infection incidence and antimicrobial resistance for multiple pathogens. We aimed to analyse trends in inpatient infection incidence and antimicrobial resistance for nine pathogens over the past 15 years across the USA. In this US nationwide retrospective cohort study, we analysed clinical microbiology data from electronic health records from all patients admitted to all 138 Veterans Affairs (VA) Medical Centers with acute care wards across the USA from Feb 1, 2007, to March 31, 2022. We quantified inpatient antibiotic use as days of therapy (DOT) per 1000 patient-days and antimicrobial resistance by resistance proportion (proportion of incident isolates identified as resistant) and phenotypic incidence (incidence of infections per 1000 admissions classified as resistant, susceptible, or missing). To analyse trends before the COVID-19 pandemic and during the COVID-19 pandemic, we used generalised estimating equation models and reported average annual percentage changes (AAPC). We collected 991 527 30-day incident isolates from 507 760 patients in 138 VA Medical Centers and 50 states in the USA. Between Feb 1, 2007, and Dec 31, 2019, infection incidence and antimicrobial resistance declined for many pathogens and pathogen-drug combinations. The proportion of methicillin resistance in Staphylococcus aureus decreased from 57·7% (11 876 of 20 584 incident isolates) to 44·6% (5916 of 13 257) over these 13 years (AAPC -1·8%; 95% CI -2·4 to -1·2; p<0·0001), and vancomycin-resistant Enterococcus faecium infections decreased from 77·8% (2555 of 3285) to 65·1% (893 of 1371; AAPC -1·2%; 95% CI -2·5 to 0·0; p=0·052). Fluoroquinolone resistance declined in both proportion and incidence for most pathogens. These trends correlated with substantial reductions in fluoroquinolone use, from 125 DOT per 1000 patient-days to 20 DOT per 1000 patient-days. Third generation cephalosporin resistance increased steeply in Escherichia coli infections from 6·7% (942 of 14 042) in 2007 to 15·3% (2153 of 14 053) in 2019 (AAPC 8·5%; 95% CI 6·2 to 10·7; p<0·0001). Carbapenem resistance proportion increased in Enterobacter cloacae infections from 1·1% (30 of 2852) in 2007 to 7·3% (212 of 2919) in 2019 (AAPC 19·8%; 95% CI 13·7 to 26·2; p<0·0001), but remained low for Klebsiella pneumoniae and E coli. During the COVID-19 pandemic between Jan 1, 2020, and March 31, 2022, several pathogen-drug combinations increased in both incidence and resistance for hospital-associated infections. For some pathogen-drug combinations, trends in incidence of resistant and susceptible infections were divergent, whereas for other combinations, these trends were in the same direction. Significant reductions in methicillin resistance in S aureus, vancomycin-resistant E faecium, and fluoroquinolone resistance across multiple pathogens suggest that control efforts have had an effect on resistance. The rise in extended-spectrum β-lactamases-producing Enterobacterales and recent surge in hospital-associated infections emphasise the need for ongoing surveillance and interventions. Our study highlights how coupling the analysis of phenotypic incidence with resistance proportion can enhance interpretation of antimicrobial resistance data. US Centers for Disease Control and Prevention.

Exploring Plant-Based Compounds as Alternatives for Targeting Enterococcus faecalis in Endodontic Therapy: A Molecular Docking Approach.

Endodontic infections pose significant challenges in dental practice due to their persistence and potential complications. Among the causative agents, Enterococcus faecalis stands out for its ability to form biofilms and develop resistance to conventional antibiotics, leading to treatment failures and recurrent infections. The urgent need for alternative treatments arises from the growing concern over antibiotic resistance and the limitations of current therapeutic options in combating E. faecalis-associated endodontic infections. Plant-based natural compounds offer a promising avenue for exploration, given their diverse bioactive properties and potential as sources of novel antimicrobial agents. In this study, molecular docking and dynamics simulations are employed to explore the interactions between SrtA, a key enzyme in E. faecalis, and plant-based natural compounds. Analysis of phytocompounds through molecular docking unveiled several candidates with binding energies surpassing that of the control drug, ampicillin, with pinocembrin emerging as the lead compound due to its strong interactions with key residues of SrtA. Comparative analysis with ampicillin underscored varying degrees of structural similarity among the study compounds. Molecular dynamics simulations provided deeper insights into the dynamic behavior and stability of protein-ligand complexes, with pinocembrin demonstrating minimal conformational changes and effective stabilization of the N-terminal region. Free energy landscape analysis supported pinocembrin's stabilizing effects, further corroborated by hydrogen bond analysis. Additionally, physicochemical properties analysis highlighted the drug-likeness of pinocembrin and glabridin. Overall, this study elucidates the potential anti-bacterial properties of selected phytocompounds against E. faecalis infections, with pinocembrin emerging as a promising lead compound for further drug development efforts, offering new avenues for combating bacterial infections and advancing therapeutic interventions in endodontic practice.

Unraveling host-pathogen dynamics in a murine model of septic peritonitis induced by vancomycin-resistant Enterococcus faecium

ABSTRACT Vancomycin-resistant Enterococcus faecium (E. faecium) infection is associated with higher mortality rates. Previous studies have emphasized the importance of innate immune cells and signalling pathways in clearing E. faecium, but a comprehensive analysis of host-pathogen interactions is lacking. Here, we investigated the interplay of host and E. faecium in a murine model of septic peritonitis. Following injection with a sublethal dose, we observed significantly increased murine sepsis score and histological score, decreased weight and bacterial burden, neutrophils and macrophages infiltration, and comprehensive activation of cytokine-mediated signalling pathway. In mice receiving a lethal dose, hypothermia significantly improved survival, reduced bacterial burden, cytokines, and CD86 expression of MHC-II+ recruited macrophages compared to the normothermia group. A mathematical model constructed by observational data from 80 animals, recapitulated the host-pathogen interplay, and further verified the benefits of hypothermia. These findings indicate that E. faecium triggers a severe activation of cytokine-mediated signalling pathway, and hypothermia can improve outcomes by reducing bacterial burden and inflammation.

A Retrospective Case Series Study of Alcaligenes faecalis Pneumonia

Background: The potentially developing human pathogen Alcaligenes faecalis is a gram-negative, nonfermenting bacterium. Treatment of A. faecalis infections is frequently difficult due to increased resistance to many antibiotics, such as β-lactam antibiotics, aminoglycosides, and quinolones. In the literature, A. faecalis pneumonia has never been documented in a case series study. Here, we provide a case series study of patients with A. faecalis pneumonia. Objectives: The aim of this study was to elucidate the clinical characteristics, management strategies, and outcomes of A. faecalis pneumonia patients. Methods: Patients with A. faecalis pneumonia between January 2014 and December 2019 were included in a retrospective investigation. We examined the clinical outcomes of patients with A. faecalis pneumonia, together with the risk factors for pneumonia, prior intravenous antibiotic use within 90 days, respiratory secretion culture results, antibiotic sensitivity test results, and other variables. Results: Observations revealed eight patients with A. faecalis pneumonia, including six males and two females. The mean age of patients was 70 years. These eight patients shared risk factors for pneumonia. Six patients were discharged, and two patients died as a result of A. faecalis pneumonia. Two patients with pneumonia caused by extensively drug-resistant A. faecalis were identified. Conclusions: Rare cases of A. faecalis pneumonia have been documented in the literature. Recently, A. faecalis has developed extensive drug resistance. To treat pneumonia caused by A. faecalis with substantial antibiotic resistance, either polymyxin B or tigecycline is needed. The clinical outcome is typically satisfactory when A. faecalis pneumonia patients receive appropriate antibiotic therapy, but cases of fatal pneumonia have been documented in the literature.

Targeted metabolomics analysis approach to unravel the biofilm formation pathways of Enterococcus faecalis clinical isolates.

(i) To characterize Enterococcus faecalis biofilm formation pathways by semi-targeted metabolomics and targeted nitrogen panel analysis of strong (Ef63) and weak (Ef 64) biofilm forming E. faecalis clinical isolates and (ii) to validate the identified metabolic markers using targeted inhibitors. Previous proteomics profiling of E. faecalis clinical isolates with strong and weak biofilm formation revealed that differences in metabolic activity levels of small molecule, nucleotide and nitrogen compound metabolic processes and biosynthetic pathways, cofactor metabolic process, cellular amino acid and derivative metabolic process and lyase activity were associated with differences in biofilm formation. Hence, semi-targeted analysis of Ef 63, Ef 64 and ATC control strain Ef 29212 was performed by selecting metabolites that were part of both the previously identified pathways and a curated library with confirmed physical and chemical identity, followed by confirmatory targeted nitrogen panel analysis. Significantly regulated metabolites (p < .05) were selected based on fold change cut-offs of 1.2 and 0.8 for upregulation and downregulation, respectively, and subjected to pathway enrichment analysis. The identified metabolites and pathways were validated by minimum biofilm inhibitory concentration (MBIC) and colony forming unit (CFU) assays with targeted inhibitors. Metabolomics analysis showed upregulation of betaine, hypoxanthine, glycerophosphorylcholine, tyrosine, inosine, allantoin and citrulline in Ef 63 w.r.t Ef 64 and Ef 29212, and thesemetabolites mapped to purinemetabolism, urea cycle and aspartate metabolism pathways. MBIC and CFU assays using compounds against selected metabolites and metabolic pathways, namely glutathione against hypoxanthine and hydroxylamine against aspartate metabolism showed inhibitory effects against E. faecalis biofilm formation. The study demonstrated the importance of oxidative stress inducers such as hypoxanthine and aspartate metabolism pathway in E. faecalis biofilm formation. Targeted therapeutics against these metabolic markers can reduce the healthcare burden associated with E. faecalis infections.

Theaflavin-3,3′-digallate effectively attenuates biofilm formation by Enterococcus faecalis via the targeting of specific quorum sensing pathways

Enterococcus faecalis, an opportunistic pathogen responsible for nosocomial infections, exhibits increased pathogenicity via biofilm formation. Theaflavin-3,3′-digallate (TF3), a theaflavin extracted from black tea, exhibits potent antibacterial effects. In the present study, we investigated the inhibitory effect of TF3 on E. faecalis. Our results indicated that TF3 significantly inhibited E. faecalis ATCC 29212 biofilm formation. This observation was further confirmed via crystal violet staining, confocal laser scanning microscopy, and field emission-scanning electron microscopy. To disclose the underlying mechanisms, RNA-seq was applied. TF3 treatment significantly altered the transcriptomic profile of E. faecalis, as evidenced by identification of 248 differentially expressed genes (DEGs). Through functional annotation of these DEGs, several quorum-sensing pathways were found to be suppressed in TF3-treated cultures. Further, gene expression verification via real-time PCR confirmed the downregulation of gelE, sprE, and secY by TF3. These findings highlighted the ability of TF3 to impede E. faecalis biofilm formation, suggesting a novel preventive strategy against E. faecalis infections.

Isolation and Characterization of the Lytic Enterococcus faecium Phage φEc-ZZ2

Infections with vancomycin-resistant Enterococcus (VRE) have been increasingly reported, especially in immunocompromised patients. Bacteriophages (phages) are often considered as potential therapeutic candidates in treating infectious diseases. To search for therapeutic phages as antimicrobial agents for the treatment of Enterococcus faecium infections, eight E. faecium phages were isolated from the environments. One of these, phage φEc-ZZ2, which was capable of eliciting efficient lysis of E. faecium, was selected for analysis. Transmission electron microscopy revealed its resemblance to members of the family Siphoviridae, with a tail 200 nm long and an icosahedral head 45 nm in diameter. Phage φEc-ZZ2 exhibited rapid adsorption (&gt; 99% adsorbed in 10 min), a short latency period of 20 min and a large burst size of 180 PFU/cell. Host range determination shows that φEc-ZZ2 has a relatively broader host range (specificity for 54.5% of tested E. faecium strains). Furthermore, when φEc-ZZ2 alone was incubated at different pH, the phage was stable over a wide pH range (5 to 9). These characteristics of φEc-ZZ2 will provide useful information for further research on the interaction between Enterococcus phages and their hosts. Moreover, in consideration of its pH stability and broader host range, φEc-ZZ2 may be a good candidate as a therapeutic/disinfectant agent to control nosocomial infections caused by E. faecium.

A novel endolysin from an Enterococcus faecalis phage and application

Enterococcus faecalis is the primary species detected in cases of secondary persistent infection resulting from root canal therapy failure. Due to the overuse of antibacterial agents, E. faecalis has developed resistance to these drugs, making it challenging to treat clinical diseases caused by E. faecalis infection. Therefore, there is an urgent need to explore new alternative drugs for treating E. faecalis infections. We aimed to clone and express the genes of phage endolysins, purify the recombinant proteins, and analyze their antibacterial activity, lysis profile, and ability to remove biofilm. The crude enzyme of phage endolysin pEF51 (0.715 mg/mL), derived from phage PEf771 infecting E. faecalis, exhibited superior bacterial inhibitory activity and a broader bactericidal spectrum than its parental phage PEf771. Furthermore, pEF51 demonstrated high efficacy in eliminating E. faecalis biofilm. Therapeutic results of the infected Sprague-Dawley (SD) rat model indicated that among 10 SD rats, only one developed a thoracic peritoneal abscess and splenic peritoneal abscess after 72 h of treatment with pEF51. This suggests that pEF51 could provide protection against E. faecalis infection in SD rats. Based on the 16S rDNA metagenomic data of the intestinal microbial community of SD rats, endolysin pEF51 exerted a certain influence on the diversity of intestinal microorganisms at the genus level. Thus, pEF51 may serve as a promising alternative to antibiotics in the management of E. faecalis infection.

Insights into the novel Enterococcus faecalis phage: A comprehensive genome analysis.

Enterococcus faecalis, a Gram-positive bacterium, poses a significant clinical challenge owing to its intrinsic resistance to a broad spectrum of antibiotics, warranting urgent exploration of innovative therapeutic strategies. This study investigated the viability of phage therapy as an alternative intervention for antibiotic-resistant E. faecalis, with a specific emphasis on the comprehensive genomic analysis of bacteriophage SAM-E.f 12. The investigation involved whole-genome sequencing of SAM-E.f 12 using Illumina technology, resulting in a robust dataset for detailed genomic characterization. Bioinformatics analyses were employed to predict genes and assign functional annotations. The bacteriophage SAM-E.f 12, which belongs to the Siphoviridae family, exhibited substantial potential, with a burst size of 5.7 PFU/infected cells and a latent period of 20 min. Host range determination experiments demonstrated its effectiveness against clinical E. faecalis strains, positioning SAM-E.f 12 as a precise therapeutic agent. Stability assays underscore resilience across diverse environmental conditions. This study provides a comprehensive understanding of SAM-E.f 12 genomic composition, lytic lifecycle parameters, and practical applications, particularly its efficacy in murine wound models. These results emphasize the promising role of phage therapy, specifically its targeted approach against antibiotic-resistant E. faecalis strains. The nuanced insights derived from this research will contribute to the ongoing pursuit of efficacious phage therapies and offer valuable implications for addressing the clinical challenges associated with E. faecalis infections.

CCR2-dependent CX3CR1+ colonic macrophages promote Enterococcus faecalis dissemination.

Enterococci are common commensal bacteria that colonize the gastrointestinal tracts of most mammals, including humans. Importantly, these bacteria are one of the leading causes of nosocomial infections. This study examined the role of colonic macrophages in facilitating Enterococcus faecalis infections in mice. We determined that depletion of colonic phagocytes resulted in the reduction of E. faecalis dissemination to the gut-draining mesenteric lymph nodes. Furthermore, we established that trafficking of monocyte-derived CX3CR1-expressing macrophages contributed to E. faecalis dissemination in a manner that was not reliant on CCR7, the conventional receptor involved in lymphatic migration. Finally, we showed that E. faecalis mutants with impaired intracellular survival exhibited reduced dissemination, suggesting that E. faecalis can exploit host immune cell migration to disseminate systemically and cause disease. Our findings indicate that modulation of macrophage trafficking in the context of antibiotic therapy could serve as a novel approach for preventing or treating opportunistic infections by disseminating enteric pathobionts like E. faecalis.

Antibacterial Activity and Mechanism of Candesartan Cilexetil against Enterococcus faecalis.

Enterococcus faecalis infections pose a significant clinical challenge due to their multidrug resistance and propensity for biofilm formation. Exploring alternative treatment options, such as repurposing existing drugs, is crucial in addressing this issue. This study investigates the antibacterial activity of candesartan cilexetil against E. faecalis and elucidates its mechanism of action. Candesartan cilexetil exhibited notable antibacterial activity against both E. faecalis and Enterococcus faecium, with minimum inhibitory concentration (MIC) of ≤25 μM. Time-kill curves demonstrated concentration-dependent bactericidal effects. Candesartan cilexetil could significantly inhibited biofilm formation at the concentration of 1/4× MIC and induced alterations in biofilm structure. Permeability assays revealed compromised bacterial membranes, accompanied by the dissipation of membrane potential in E. faecalis cells after treatment with candesartan cilexetil. Checkerboard analysis showed that bacterial membrane phospholipids phosphatidylglycerol and cardiolipin could neutralize the antibacterial activity of candesartan cilexetil in a dose-dependent manner. Biolayer interferometry (BLI) assay indicated specific interactions between candesartan cilexetil and phosphatidylglycerol or cardiolipin. This study demonstrates the promising antibacterial and antibiofilm activities of candesartan cilexetil against multidrug-resistant E. faecalis. The mechanism of action involves disruption of bacterial membranes, possibly by interacting with membrane phospholipids. These findings underscore the potential utility of candesartan cilexetil as an effective therapeutic agent for combating E. faecalis infections, offering a valuable strategy in the battle against antibiotic-resistant pathogens.

Influence of preoperative urine culture and bacterial species on urogenital sepsis after ureteral flexible lithotripsy in patients with upper urinary tract stones.

This retrospective study aims to identify risk factors for urogenic sepsis in patients with upper urinary tract stones following ureteral flexible lithotripsy (FURL). Additionally, we analyze the clinical characteristics of bacterial infections post-surgery. A total of 759 patients who underwent FURL at the Urology Department of Zunyi Medical University were included. Univariate and multivariate Logistic regression analyses were conducted to identify independent risk factors for urogenic sepsis post-FURL. The distribution of bacteria based on preoperative urine cultures was also analyzed. Statistical analysis was performed using R4.2.2 software. Of the 759 patients, positive preoperative urine culture, urine nitrite positivity, urine white blood cell count (WBC) ≥ 200 cells/μL, residual stones, and neutrophil-to-lymphocyte ratio (NLR) were found to be independent risk factors for urogenic sepsis after FURL. Among the 164 patients with positive preoperative urine cultures, 32 developed urogenic sepsis post-surgery, with 68.75% having positive preoperative cultures. The leading pathogens causing postoperative urogenic sepsis were Escherichia coli (E. coli), Enterococcus faecium, Proteus mirabilis, and Klebsiella pneumoniae. The probabilities of progression to urogenic sepsis were as follows: E. coli 19% (n = 12), Enterococcus faecium 43% (n = 3), Proteus mirabilis 33.3% (n = 1), and Klebsiella pneumoniae 33.3% (n = 1). The ages of affected patients were 47.17 ± 13.2, 53.7, 41, and 79 years, respectively. Rates of comorbid diabetes were 36.4, 66.7, 50, 100%, with nitrite positivity rates at 72.7, 33.3, 50, 0%. Ten female patients were infected with E. coli, while patients infected with Klebsiella pneumoniae had an NLR of 7.62. Positive preoperative urine culture, urine nitrite positivity, urine WBC ≥ 200 cells/μL, residual stones, and NLR are independent risk factors for urogenic sepsis after FURL. Escherichia coli is the predominant pathogen post-FURL, with notable female prevalence and nitrite-positive urine in infections. Enterococcus faecium infections are associated with diabetes.

LiaX is a surrogate marker for cell envelope stress and daptomycin non-susceptibility in Enterococcus faecium.

Daptomycin (DAP) is often used as a first-line therapy to treat vancomycin-resistant Enterococcus faecium infections, but emergence of DAP non-susceptibility threatens the effectiveness of this antibiotic. Moreover, current methods to determine DAP minimum inhibitory concentrations (MICs) have poor reproducibility and accuracy. In enterococci, DAP resistance is mediated by the LiaFSR cell membrane stress response system, and deletion of liaR encoding the response regulator results in hypersusceptibility to DAP and antimicrobial peptides. The main genes regulated by LiaR are a cluster of three genes, designated liaXYZ. In Enterococcus faecalis, LiaX is surface-exposed with a C-terminus that functions as a negative regulator of cell membrane remodeling and an N-terminal domain that is released to the extracellular medium where it binds DAP. Thus, in E. faecalis, LiaX functions as a sentinel molecule recognizing DAP and controlling the cell membrane response, but less is known about LiaX in E. faecium. Here, we found that liaX is essential in E. faecium with an activated LiaFSR system. Unlike E. faecalis, E. faecium LiaX is not detected in the extracellular milieu and does not appear to alter phospholipid architecture. We further postulated that LiaX could be used as a surrogate marker for cell envelope activation and non-susceptibility to DAP. For this purpose, we developed and optimized a LiaX enzyme-linked immunosorbent assay (ELISA). We then assessed 86 clinical E. faecium bloodstream isolates for DAP MICs and used whole genome sequencing to assess for substitutions in LiaX. All DAP-resistant clinical strains of E. faecium exhibited elevated LiaX levels. Strikingly, 73% of DAP-susceptible isolates by standard MIC determination also had elevated LiaX ELISAs compared to a well-characterized DAP-susceptible strain. Phylogenetic analyses of predicted amino acid substitutions showed 12 different variants of LiaX without a specific association with DAP MIC or LiaX ELISA values. Our findings also suggest that many E. faecium isolates that test DAP susceptible by standard MIC determination are likely to have an activated cell stress response that may predispose to DAP failure. As LiaX appears to be essential for the cell envelope response to DAP, its detection could prove useful to improve the accuracy of susceptibility testing by anticipating therapeutic failure.

Protective effect of microbisporicin (NAI-107) against vancomycin resistant Enterococcus faecium infection in a Galleria mellonella model.

Increasing antimicrobial resistance in Enterococcus faecium necessitates the search for novel treatment agents, such as bacteriocins. In this study, we conducted an in vivo assessment of five bacteriocins, namely Lacticin Z, Lacticin Q, Garvicin KS (ABC), Aureocin A53 and Microbisporicin (NAI-107), against vanB-resistant Enterococcus faecium using a Galleria mellonella model. Our in vitro experiments demonstrated the efficacy of all five bacteriocins against vanB-resistant E. faecium with only NAI-107 demonstrating in vivo efficacy. Notably, NAI-107 exhibited efficacy across a range of tested doses, with the highest efficacy observed at a concentration of 16µg/mL. Mortality rates in the group treated with 16µg/mL NAI-107 were lower than those observed in the linezolid-treated group. These findings strongly suggest that NAI-107 holds promise as a potential alternative therapeutic agent for treating infections caused by resistant E. faecium and warrants further investigation.

Bacteriophage and antibiotic combination therapy for recurrent Enterococcus faecium bacteremia.

Phage therapy is an emerging therapeutic approach for treating bacterial infections that do not respond to traditional antibiotics. The addition of phage therapy to systemic antibiotics to treat a patient with recurrent E. faecium infections that were non-responsive to antibiotics alone resulted in fewer hospitalizations and improved the patient's quality of life. Combination phage and antibiotic therapy reduced E. faecium and VRE abundance in the patient's stool. Eventually, an anti-phage antibody response emerged that was able to neutralize phage activity, which may have limited clinical efficacy. This study demonstrates the potential of phages as an additional option in the antimicrobial toolbox for treating invasive enterococcal infections and highlights the need for further investigation to ensure phage therapy can be deployed for maximum clinical benefit.