Pathogen Enterococcus Faecalis Research Articles

Rolling down the pilus formation of gram-positive bacteria: underlining the importance of Sortase C as a drug target.

Bacteria possess hair-like projections on their surface termed pili. The primary function of a pilus is to enable bacterial cell attachment to the host. Since pili are associated with cell adhesion, they play a major role in bacterial colonization and infection. Due to their important functional role, these surface appendages become ideal drug targets, hence it is essential to study the mechanism associated with pilus assembly, elongation, and attachment. Several enzymes are required for pilus biosynthesis, and their adhesion to the host. In this review paper, we have described the importance of the Sortase C (SrtC) protein which is required for pilus assembly and pilin polymerization. We also provide a detailed structural comparison of the protein from various pathogenic bacteria and highlight the importance of SrtC as a drug target. In addition to this, we have also reported structural studies of SrtC from the pathogenic bacteria Enterococcus faecalis using homology modelling.

Effects of Vitamin E and/or selenium nanoparticles on organ histology, hemato-biochemical parameters, immunity, gene expression, and growth performance in Nile tilapia challenged with Enterococcus faecalis

A two-month feeding experiment was conducted to assess the impact of dietary selenium nanoparticles (SeNPs), sodium selenite (Se), and vitamin E (Vit E) on the growth performance, hematology profile, innate immune response, histomorphology of the liver, intestine, and gills, as well as gene expression in Nile tilapia (Oreochromis niloticus) challenged with the pathogenic bacteria Enterococcus faecalis. A total of 360 fish were allocated into six experimental groups and fed diets containing 1 mg/kg of SeNPs (SeNPs), 1 mg /kg of sodium selenite (Se), 100 mg/kg of Vit E (VE), SeNPs+ Vit E, Se+ Vit E and a control group (CON) without any additives. The results showed that SeNPs and SeNPs+ Vit E diets significantly improved the growth performance (final body weight, feed intake, fish biomass, specific growth rate, and feed conversion ratio) and blood parameters compared to the other groups (P<0.05). Liver enzymes (AST, ALT, and ALP) were significantly decreased, while immune responses were enhanced in the serum of fish in the SeNPs and SeNPs+ Vit E groups before and after the E. faecalis challenge. The expression of pro-inflammatory genes (TNF-α and IL-8) was significantly lower in the SeNPs and SeNPs+ Vit E groups, both before and after the E. faecalis challenge, compared to the other groups (P<0.05). Nile tilapia fed the control diet and challenged with E. faecalis exhibited a high mortality rate (85 %), whereas mortality was significantly lower in fish fed supplemental SeNPs (45 %) and SeNPs+ Vit E (40 %). Histological examination also revealed improvements in liver, intestine, and gill functions in Nile tilapia fed SeNPs+ Vit E. These results suggest that dietary SeNPs, either alone or in combination with Vit E, can significantly enhance fish performance, innate immune response, liver function enzymes, and reduce the expression of pro-inflammatory genes in Nile tilapia. They can also mitigate the pathological effects caused by the E. faecalis challenge.

Ferumoxytol nanozymes effectively target chronic biofilm infections in apical periodontitis.

Bacterial biofilms are pervasive and recalcitrant to current antimicrobials, causing numerous infections. Iron oxide-nanozymes, including an FDA-approved formulation (ferumoxytol, FMX), show potential against biofilm infections via catalytic activation of hydrogen peroxide (H2O2). However, clinical evidence on its efficacy and therapeutic mechanisms is lacking. Here, we investigate whether FMX-nanozymes can treat chronic biofilm infections and compare their bioactivity to gold-standard sodium hypochlorite (NaOCl), a potent but caustic disinfectant. Clinical performance was assessed in patients with apical periodontitis, an intractable endodontic infection affecting half of the global adult population. Data show robust antibiofilm activity by a single application of FMX with H2O2 achieving results comparable to NaOCl without adverse effects. FMX binds efficiently to bacterial pathogens Enterococcus faecalis and Fusobacterium nucleatum and remains catalytically active without being affected by dental tissues. This allows for effective eradication of endodontic biofilms via on-site free-radical generation without inducing cytotoxicity. Unexpectedly, FMX promotes growth of stem cells of apical papilla (SCAP), with transcriptomic analyses revealing upregulation of proliferation-associated pathways and downregulation of cell-cycle suppressor genes. Notably, FMX activates SCAP pluripotency and WNT/NOTCH signaling that induces its osteogenic capacity. Together, we show FMX nanozymes are clinically effective against severe chronic biofilm infection with pathogen targeting and unique stem cell-stimulatory properties, offering a regenerative approach to antimicrobial therapy.

Antimicrobial Resistance Profile of Zoonotic Clinically Relevant WHO Priority Pathogens.

The World Health Organization announced critically important bacterial and fungal pathogens displaying alarming levels of antimicrobial resistance, which currently represent difficult-to-treat cases of morbidity. Within this grouping, the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) are causative of significant morbidity and mortality. Studies described herein demonstrate the presence of critically important fungal and ESKAPE bacterial species in companion animals which are zoonotic in nature. The relationship between the environment, animals, and human infectious disease has long been recognized as part of One Health. This research investigates the resistance patterns of isolated zoonotic pathogens using recognized in vitro methodologies, namely disk diffusion, minimum inhibitory concentration testing, and genetic screening. Antibiotic susceptibility testing and gene analysis demonstrated an association between multi-drug resistance and extended beta spectrum lactamase production in critical-priority bacteria. Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa exhibit great levels of multi-drug resistance. Fungal isolates demonstrated high levels of resistance, with Amphotericin B proving the most effective antifungal agent investigated. The level of antimicrobial resistance present in clinically relevant bacterial and fungal pathogens isolated from animal cases of morbidity in this study is alarming. In conclusion, this study shows that animals can act as a reservoir facilitating the transmission of antibiotic-resistant pathogens and genes zoonotically.

Use of T2Bacteria Panel in Pediatric Hematopoietic Stem Cell Transplant Patients: A Single Center Experience

Abstract Background Bloodstream infection is a common complication following hematopoietic cell transplant (HCT), occurring in 10-40% of patients (1,2). Rapid identification of causative bacteria is imperative to provide proper empiric therapy and ensure optimal patient outcomes. The T2Bacteria Panel detects five bacterial pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Escherichia coli) using T2 magnetic resonance (T2MR, T2Biosystems, Lexington MA, USA) directly from blood specimens. Previous studies have reported per-patient sensitivity, specificity, and negative predictive value (NPV) of 84-90%, 85.9-90%, and 99.7%, respectively, as well as 100% positive agreement and 98.4% negative agreement when compared to blood culture (3-5). To date, there have been no studies on the use of this test in pediatric HCT recipients. Methods We reviewed all pediatric HCT patients at St. Jude Children’s Research Hospital who had a T2Bacteria Panel performed for fever and suspected infection between January 2019 and September 2022. A total of 706 T2Bacteria Panel results and concurrent blood culture results from 251 unique patients were analyzed to determine assay performance for detection of the 5 targeted pathogens. Results T2Bacteria PCR and blood culture showed concordant results in 97% of cases. Overall, our study revealed 65% positive percent agreement with blood culture and 95% negative percent agreement for bacteremia caused by any of the target pathogens. PPV, NPV, sensitivity and specificity for each organism detected by the panel, and the panel overall, are presented in Table 1. Positive predictive value ranged from 28-73%. Negative predictive value was high for all organisms (98-100%). Sensitivity was highest for Pseudomonas aeruginosa (88%), and lowest for Escherichia coli (44%). Specificity was high for all organisms (97-99%). Conclusion In pediatric HSCT patients, the T2Bacteria Panel was most useful for rapidly ruling out the presence of target pathogens, with high negative percent agreement, NPV, and specificity. Positive percent agreement was lower than noted in previous studies. Positive predictive value and sensitivity varied per pathogen.

Impact of ESKAPE Pathogens on Bacteremia: A Three-Year Surveillance Study at a Major Hospital in Southern Italy.

ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pose a serious public health threat as they are resistant to multiple antimicrobial agents. Bloodstream infections (BSIs) caused by ESKAPE bacteria have high mortality rates due to the limited availability of effective antimicrobials. This study aimed to evaluate the prevalence and susceptibility of ESKAPE pathogens causing BSIs over three years in a large tertiary hospital in Salerno. Conducted at the Clinical Microbiology Laboratory of San Giovanni di Dio e ''Ruggi D'Aragona'' Hospital from January 2020 to December 2022, blood culture samples from different departments were incubated in the BD BACTEC™ system for 5 days. Species identification was performed using MALDI-TOF MS, and antimicrobial resistance patterns were determined by the VITEK2 system. Out of 3197 species isolated from positive blood cultures, 38.7% were ESKAPE bacteria. Of these, 59.9% were found in blood culture samples taken from men, and the most affected age group was those aged >60 years. (70.6%). Staphylococcus aureus was the main BSI pathogen (26.3%), followed by Klebsiella pneumoniae (15.8%). Significant resistance rates were found, including 35% of Staphylococcus aureus being resistant to oxacillin and over 90% of Acinetobacter baumannii being resistant to carbapenems. These results highlight the urgent need for antimicrobial stewardship programs to prevent incurable infections.

Vaccines and monoclonal antibodies to prevent healthcare-associated bacterial infections.

SUMMARYHealthcare-associated infections (HAIs) represent a burden for public health with a high prevalence and high death rates associated with them. Pathogens with a high potential for antimicrobial resistance, such as ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and Clostridioides difficile, are responsible for most HAIs. Despite the implementation of infection prevention and control intervention, globally, HAIs prevalence is stable and they are mainly due to endogenous pathogens. It is undeniable that complementary to infection prevention and control measures, prophylactic approaches by active or passive immunization are needed. Specific groups at-risk (elderly people, chronic condition as immunocompromised) and also healthcare workers are key targets. Medical procedures and specific interventions are known to be at risk of HAIs, in addition to hospital environmental exposure. Vaccines or monoclonal antibodies can be seen as attractive preventive approaches for HAIs. In this review, we present an overview of the vaccines and monoclonal antibodies in clinical development for prevention of the major bacterial HAIs pathogens. Based on the current state of knowledge, we look at the challenges and future perspectives to improve prevention by these means.

Strategies to Overcome Antimicrobial Resistance in Nosocomial Infections, A Review and Update.

Nosocomial infections, also known as healthcare-associated infections, are a significant global concern due to their strong association with high mortality and morbidity in both developed and developing countries. These infections are caused by a variety of pathogens, particularly the ESKAPE group of bacteria, which includes the six pathogens Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. These bacteria have demonstrated noteworthy resistance to different antibiotics. Antimicrobial resistance mechanisms can manifest in various forms, including restricting drug uptake, modifying drug targets, inactivating drugs, active drug efflux, and biofilm formation. Accordingly, various strategies have been developed to combat antibiotic-resistant bacteria. These strategies encompass the development of new antibiotics, the utilization of bacteriophages that specifically target these bacteria, antimicrobial combination therapy and the use of peptides or enzymes that target the genomes or essential proteins of resistant bacteria. Among promising approaches to overcome antibiotic resistance, the CRISPR/Cas system stands out and offers many advantages. This system enables precise and efficient editing of genetic material at specific locations in the genome. Functioning as a bacterial "adaptive immune system," the CRISPR/Cas system recognizes, degrades, and remembers foreign DNA sequences through the use of spacer DNA segments that are transcribed into CRISPR RNAs (crRNA). This paper has focused on nosocomial infections, specifically the pathogens involved in hospital infections, the mechanisms underlying bacterial resistance, and the strategies currently employed to address this issue. Special emphasis has been placed on the application of CRISPR/Cas technology for overcoming antimicrobial resistance.

ESKAPE Pathogens: Antimicrobial Resistance Patterns, Risk Factors, and Outcomes a Retrospective Cross-Sectional Study of Hospitalized Patients in Palestine.

Antimicrobial resistance to ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp). remains a major challenge in hospital settings. This study aimed to determine the ESKAPE antimicrobial resistance patterns and associated factors with multi-drug resistance strains among hospitalized patients in a single tertiary care medical hospital in Palestine. A single-center retrospective cross-sectional study was conducted by reviewing patients' electronic medical records and laboratory results from November 1, 2021, to November 30, 2022, at the Palestine Medical Complex in Palestine. The study included patients aged > 18 years who had been infected with ESKAPE pathogens 48 hours after hospital admission. This study included 231 patients, of whom 90.5% had MDR infections. In total, 331 clinical samples of ESKAPE pathogens were identified. A. baumannii was the most prevalent MDR pathogen (95.6%) with Carbapenem-resistant exceeding 95%, followed by K. pneumoniae (83.8%) with extended-spectrum cephalosporin resistance exceeding 90%, S. aureus (68.2) with 85% oxacillin-resistance, E. faecium (40%) with 20% vancomycin resistance, P. aeruginosa (22.6%) with 30% carbapenem resistance. Furthermore, emergent colistin resistance has been observed in A. baumannii, K. pneumoniae, and P. aerogenesis. Risk factors for MDR infection included age (p< 0.035), department (p< 0.001), and invasive procedures such as IUC (p< 0.001), CVC (p< 0.000), and MV (p< 0.008). Patients diagnosed with MDR bacteria had increased 30-day mortality (p< 0.001). The findings of this study show alarming MDR among hospitalized patients infected with ESKAPE pathogens, with resistance to first-line antimicrobial agents and emerging resistance to colistin, minimizing treatment options. Healthcare providers and the Ministry of Health must take steps, adopt policies to prevent antimicrobial resistance, adhere to infection control guidelines, implement antimicrobial stewardship programs to prevent and limit the growing health crisis, and support research to discover new treatment options.

Antimicrobial resistance in Klebsiella pneumoniae: an overview of common mechanisms and a current Canadian perspective.

Klebsiella pneumoniae is a ubiquitous opportunistic pathogen of the family Enterobacteriaceae. K. pneumoniae is a member of the ESKAPEE pathogens (Enterococcus faecium, Staphylococcus aureus, K. pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp., and Escherichia coli), a group of bacteria that cause nosocomial infections and are able to resist killing by commonly relied upon antimicrobial agents. The acquisition of antimicrobial resistance (AMR) genes is increasing among community and clinical isolates of K. pneumoniae, making K. pneumoniae a rising threat to human health. In addition to the increase in AMR, K. pneumoniae is also thought to disseminate AMR genes to other bacterial species. In this review, the known mechanisms of K. pneumoniae AMR will be described and the current state of AMR K. pneumoniae within Canada will be discussed, including the impact of the coronavirus disease-2019 pandemic, current perspectives, and outlook for the future.

Dissecting the Enterococcal Polysaccharide Antigen (EPA) structure to explore innate immune evasion and phage specificity

Streptococci, Lactococci and Enterococci all produce L-rhamnose-containing cell wall polysaccharides which define Lancefield serotypes and represent promising candidates for the design of glycoconjugate vaccines. The L-rhamnose containing Enterococcal Polysaccharide Antigen (EPA), produced by the opportunistic pathogen Enterococcus faecalis, plays a critical role in normal growth, division, biofilm formation, antimicrobial resistance, phage susceptibility, and innate immune evasion. Despite the critical role of this polymer in E. faecalis physiology and host-pathogen interactions, little information is available on its structure and biosynthesis. Here, using an NMR approach, we elucidate the structure of EPA and propose a model for biosynthesis. We report the structure of the EPA-peptidoglycan linkage unit and reveal an unprecedented complexity of the EPA rhamnose backbone and decoration subunits. Finally, we explore the impact of several EPA structural modifications on innate immune evasion and recognition by bacteriophages. This work represents a first step towards the functional characterisation of EPA and the rational design of therapeutic strategies against a group of important pathogens.

ALAT PENYINARAN GERMISID ULTRAUNGU (UVGI) JENIS C BERJAYA MEMBASMI PERTUMBUHAN DAN MENGHALANG PENYEBARAN PATOGEN MELALUI FOMIT

The emergence of hospital-acquired or nosocomial infection caused by ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter sp.) that are resistant to antibiotics poses public healthcare concern. Transmission of the pathogens to patients and healthcare workers can occur through various types of fomites. Pathogens can be eradicated by using UV radiation type C (UVC). In this work, several fomite samples (cloth, paper, skin, and plastic) have been contaminated with pathogens. They were then irradiated with UVC using LembayUVng®. The effectiveness was quantitatively evaluated by comparing the bacterial growth on the formite samples before and after irradiation. The results show that UVC radiation has 90-100% average efficiency in pathogen eradication against several different strains. This study provides valuable information on selection of effective method for infection control.

An enterococcal phage-derived enzyme suppresses graft-versus-host disease

Changes in the gut microbiome have pivotal roles in the pathogenesis of acute graft-versus-host disease (aGVHD) after allogenic haematopoietic cell transplantation (allo-HCT)1–6. However, effective methods for safely resolving gut dysbiosis have not yet been established. An expansion of the pathogen Enterococcus faecalis in the intestine, associated with dysbiosis, has been shown to be a risk factor for aGVHD7–10. Here we analyse the intestinal microbiome of patients with allo-HCT, and find that E. faecalis escapes elimination and proliferates in the intestine by forming biofilms, rather than by acquiring drug-resistance genes. We isolated cytolysin-positive highly pathogenic E. faecalis from faecal samples and identified an anti-E. faecalis enzyme derived from E. faecalis-specific bacteriophages by analysing bacterial whole-genome sequencing data. The antibacterial enzyme had lytic activity against the biofilm of E. faecalis in vitro and in vivo. Furthermore, in aGVHD-induced gnotobiotic mice that were colonized with E. faecalis or with patient faecal samples characterized by the domination of Enterococcus, levels of intestinal cytolysin-positive E.faecalis were decreased and survival was significantly increased in the group that was treated with the E. faecalis-specific enzyme, compared with controls. Thus, administration of a phage-derived antibacterial enzyme that is specific to biofilm-forming pathogenic E. faecalis—which is difficult to eliminate with existing antibiotics—might provide an approach to protect against aGVHD.

Enterococcus faecium: evolution, adaptation, pathogenesis and emerging therapeutics.

The opportunistic pathogen Enterococcus faecium colonizes humans and a wide range of animals, endures numerous stresses, resists antibiotic treatment and stubbornly persists in clinical environments. The widespread application of antibiotics in hospitals and agriculture has contributed to the emergence of vancomycin-resistant E. faecium, which causes many hospital-acquired infections. In this Review, we explore recent discoveries about the evolutionary history, the environmental adaptation and the colonization and dissemination mechanisms of E. faecium and vancomycin-resistant E. faecium. These studies provide critical insights necessary for developing novel preventive and therapeutic approaches against vancomycin-resistant E. faecium and also reveal the intricate interrelationships between the environment, the microorganism and the host, providing knowledge that is broadly relevant to how antibiotic-resistant pathogens emerge and endure.

Current trends in antimicrobial resistance of ESKAPEEc pathogens from bloodstream infections – Experience of a tertiary care centre in North India

IntroductionBloodstream infections (BSI) due to ESKAPEEc pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanni, Pseudomonas aeruginosa, Enterobacter spp. and Escherichia coli), cause significant mobility and mortality worldwide and are among the most common healthcare associated infections. Rising rates of antimicrobial resistance (AMR) in India are alarming, because of the high infection rates and poor control of antibiotic use. This single-centre, retrospective study was undertaken to identify the patterns of distribution and antimicrobial resistance of ESKAPEEc pathogens in bloodstream infections. MethodologyBlood samples from patients with suspected BSI were cultured and antimicrobial susceptibility testing was performed on automated systems (BD Bactec Fx/BactAlert 3D and Vitek2). The microbiological data on bacterial BSI was retrieved from the laboratory records and antimicrobial resistance profiles were analysed. Results10.7% of the blood culture samples showed bacterial growth during the study period (adult > paediatric and intensive care unit (ICU) > ward > outpatient department (OPD)). E. coli (24%) and K. pneumoniae (20.5%) were the predominant species isolated, followed by S. aureus (9.5%) and A. baumanni (9%). High rates of resistance to third generation cephalosporins, β-lactam-β-lactamase inhibitor combinations (BL-BLI) and carbapenems was observed, in Gram-negative isolates, especially from ICU patients. Methicillin-resistant S. aureus (MRSA) isolates increased from 67% to 88% over the five-year period. Vancomycin-resistance among Enterococcus isolates also escalated to 40% in 2022 with 11% linezolid resistance. ConclusionThe study revealed that more than 77% of bloodstream infections were caused by ESKAPEEc pathogens, with high rates of resistance to most antimicrobials. This reinforces the importance of monitoring the frequency of bacteria and antibiograms in individual treatment and hospital infection control programs.

Assessing the impact of positive cultures in preservation fluid on renal transplant outcomes: a scoping review.

Infection following kidney transplantation is a significant risk factor for adverse outcomes. While the donor may be a source of infection, microbiological assessment of the preservation fluid (PF) can mitigate potential recipient contamination and help curb unnecessary antibiotic use. This scoping review aimed to describe the available literature on the association between culture-positive preservation fluid, its clinically relevant outcomes, and management. Following the Joanna Briggs Institute's scoping review recommendations, a comprehensive search in databases (EMBASE, MEDLINE, and gray literature) was conducted, with data independently extracted by two researchers from selected studies. We analysed 24 articles involving 12,052 samples, predominantly published post-2000, 91%of whichretrospective. The prevalence of culture-positive preservation fluid varied from 0.86 to 77.8%. Coagulase-negative staphylococci emerged as the most frequently isolated pathogen in 14 studies. The presence of ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species), observed in two studies involving 1074 donors, was significantly associated with an increased risk of probable donor-derived infections (p-DDI). Of the reviewed articles, 14 reported on probable donor-derived infections, while 19 addressed the topic of preemptive antibiotic therapy. Routine culturing of preservation fluid is crucial for the identification of pathogenic organisms, facilitates targeted treatment and prevents probable donor-derived infections. Furthermore, this approach helps avoid the treatment of low-virulence contaminants, thereby reducing unnecessary antimicrobial use and the risk of antibiotic resistance. In cases where ESKAPE or Candida species are detected, preemptive therapy appears to be an important strategy. Given that the current evidence primarily stems from retrospective studies, there is a pressing need for large-scale, prospective trials to corroborate these recommendations. This scoping review currently represents the most thorough compilation of evidence on how contamination of preservation fluids affects kidney transplant management.

Navigating ESKAPE Pathogens: Considerations and Caveats for Animal Infection Models Development.

The misuse of antibiotics has led to the global spread of drug-resistant bacteria, especially multi-drug-resistant (MDR) ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). These opportunistic bacteria pose a significant threat, in particular within hospitals, where they cause nosocomial infections, leading to substantial morbidity and mortality. To comprehensively explore ESKAPE pathogenesis, virulence, host immune response, diagnostics, and therapeutics, researchers increasingly rely on necessitate suitable animal infection models. However, no single model can fully replicate all aspects of infectious diseases. Notably when studying opportunistic pathogens in immunocompetent hosts, rapid clearance by the host immune system can limit the expression of characteristic disease symptoms. In this study, we examine the critical role of animal infection models in understanding ESKAPE pathogens, addressing limitations and research gaps. We discuss applications and highlight key considerations for effective models. Thoughtful decisions on disease replication, parameter monitoring, and data collection are crucial for model reliability. By meticulously replicating human diseases and addressing limitations, researchers maximize the potential of animal infection models. This aids in targeted therapeutic development, bridges knowledge gaps, and helps combat MDR ESKAPE pathogens, safeguarding public health.

Epidemiology and genetic diversity of linezolid-resistant Enterococcus clinical isolates in Belgium from 2013 to 2021

ObjectivesLinezolid-resistant opportunistic human pathogens Enterococcus faecalis and Enterococcus faecium are emerging health threats as limited therapeutic options remain. The aim of this study was to investigate the epidemiology, resistance mechanisms, and genetic diversity of linezolid-resistant enterococci (LRE) isolated between 2013 and 2021 and received at the Belgian National Reference Centre (NRC) for Enterococci. MethodsLinezolid susceptibility testing was performed upon request on 2458 submitted enterococci strains. Whole-genome sequencing was performed on all LRE strains. ResultsSeventy-eight LRE human isolates, of which 63 (81%) E. faecalis and 15 (19%) E. faecium strains, were submitted to the Belgian NRC for Enterococci. Of the linezolid-resistant E. faecalis strains, 97% harboured the optrA gene (56% wild-type pE349) and 3% the poxtA gene. Of the linezolid-resistant E. faecium strains, 54% harboured the G2576T point mutation in the V domain of the 23S rRNA genes, 23% the poxtA, and 23% the optrA gene. Furthermore, two E. faecium strains were identified with a combination of two resistance mechanisms ([i] optrA and poxtA, and [ii] cfr(B) and G2576T point mutation, respectively). Vancomycin resistance was observed in 15% (n = 12) of the LRE. ST480 (n = 42/63 typed strains, 67%) was the most frequently detected sequence type (ST) in linezolid-resistant E. faecalis strains, while ST203 (n = 5/15 typed strains, 33%) was the most frequently detected ST in linezolid-resistant E. faecium strains. ConclusionsE. faecalis isolates harbouring optrA were the predominant LRE in Belgium, with ST480 as the most prominent multilocus sequence typing. Linezolid resistance in E. faecium could be attributed to either chromosomal mutations or transferable resistance determinants.

Chemosensory detection of polyamine metabolites guides C. elegans to nutritive microbes.

Much is known about molecular mechanisms by which animals detect pathogenic microbes, but how animals sense beneficial microbes remains poorly understood. The roundworm Caenorhabditis elegans is a microbivore that must distinguish nutritive microbes from pathogens. We characterized a neural circuit used by C. elegans to rapidly discriminate between nutritive bacteria and pathogens. Distinct sensory neuron populations responded to chemical cues from nutritive Escherichia coli and pathogenic Enterococcus faecalis, and these neural signals are decoded by downstream AIB interneurons. The polyamine metabolites cadaverine, putrescine, and spermidine produced by E. coli activate this neural circuit and elicit positive chemotaxis. Our study shows how polyamine odorants can be sensed by animals as proxies for microbe identity and suggests that, hence, polyamines might have widespread roles brokering host-microbe interactions.

Novel bioactive nanospheres show effective antibacterial effect against multiple endodontic pathogens

AimThe current study evaluated the antibacterial activity of a newly developed quaternary ammonium polymethacrylate (QAPM)-containing bioactive glasses (BGs) via a two-step method by our group, namely BGs-HAEMB, and explored its cytotoxicity and biocompatibility. MethodsThe antibacterial effects of the BGs-HAEMB against planktonic bacteria, bacterial biofilm formation, and experimental root canal biofilms of persistent pathogens (Enterococcus faecalis, Streptococcus sanguis and Porphyromonas endodontalis) associated with endodontic infection were evaluated in vitro by agar diffusion tests, direct contact tests and live/dead staining. The cytotoxicity and biocompatibility of BGs-HAEMB were evaluated by CCK-8 assays in vitro and a skin implantation model in vivo. ResultsCompared to three clinically used endodontic sealers (Endofill, AH Plus, and iRoot SP), BGs-HAEMB exhibited the relatively strongest antibacterial effect against E. faecalis, S. sanguis and P. endodontalis after sitting for 14 and 28 days (P < 0.01). SEM images and CLSM images also showed that for each tested bacteria, BGs-HAEMB killed the most microorganism among all the experimental groups, regardless of treatment for 7 days or 28 days (P < 0.05). Besides, the BGs-HAEMB-treated groups showed a relatively low cytotoxicity (RGRs ranging from 88.6% to 102.9%) after 1, 3, and 7 days of exposure. Meanwhile, after 28 days of implantation, the inflammatory grade in BGs-HAEMB treated group was assessed as Grade I, in which the average numbers of inflammatory cells (6.7 ± 2.1) were less than 25. ConclusionsBGs-HAEMB exerted a long-term and stable antibacterial effect. The remarkable biocompatibility of BGs-HAEMB in vitro and in vivo confirmed its possible clinical application as a potential alternative in the development of the next generation of endodontic sealers.