Pathogenicity of Enterococci

Redesigning oxazolidinones as carbonic anhydrase inhibitors against vancomycin-resistant enterococci

The rise of vancomycin-resistant enterococci (VRE) as a leading cause of hospital-acquired infections underscores the urgent need for new treatment strategies. In fact, resistance has developed not only to vancomycin but also to other clinically used agents, such as daptomycin and linezolid. We propose a novel drug design approach merging tedizolid, a second-generation oxazolidinone used as an unapproved salvage therapy in clinical settings, with carbonic anhydrase inhibitors (CAIs) recently validated as functioning decolonization agents. These sulfonamide derivatives showed potent inhibition of the carbonic anhydrases from Enterococcus faecium, with KI values in the range of 14.6-598 nM and 63.2-798 nM against EfCAα and EfCAγ. Computational simulations elucidated the binding mode of these dual-action antibiotics to the peptidyl transferase center (PTC) of the 50S ribosome subunit and bacterial CAs. A subset of six derivatives showed potent PTC-related anti-enterococcal effects against multidrug-resistant E. faecalis and E. faecium strains with some compounds outperforming both the oxazolidinone and CA inhibitor drugs (MIC values in the range 1-4 μg/mL).

Sequencing and genome-scale virulome reconstruction of Enterococcus faecalis clinical isolates delineate genes involved in gelatinase activity and biofilm formation

INTRODUCTION

Enterococci are a leading cause of nosocomial infections with a wide array of virulence factors. Clinically isolated enterococci vary in gelatinase activity and biofilm-forming ability, yet the genetic basis for this variation is not fully understood.

AIM

This study aimed to identify genetic factors associated with the discrepancy in biofilm formation and gelatinase activity.

METHODS

Biofilm formation was quantified by the crystal violet assay and the gelatinase activity was determined on gelatin agar plates. The genomes of 33 clinical Enterococcus faecalis isolates were sequenced by Illumina HiSeq and annotated by the Rapid Annotations using Subsystems Technology tool kit (RASTtk) and tools within the Bacterial Viral Bioinfromatic Resource Center (BV-BRC). Virulence factors and prophages were predicted, and genotype-phenotype associations were statistically assessed.

RESULTS

All isolates formed biofilms with different intensities, with the majority (65 %) forming moderate to strong biofilms. Gelatinase activity was detected in 39 % of isolates. The hyaluronic acid precursor gene (EF0818), adhesion protein gene (prgB/asc10), manganese uptake gene (psaA), enterococcal surface protein gene (esp), and the complete capsule locus (cps) were significantly positively correlated with biofilm intensity (p < 0.05), while the quorum sensing genes, fsrA and fsrB, collagen adhesion gene (ace), and capsule gene, cpsF, were significantly positively correlated with gelatinase activity (p < 0.05). Prophage content was positively associated with biofilm formation.

CONCLUSION

Whole-genome sequencing identified genes and prophages linked to biofilm formation and gelatinase activity in E. faecalis. Future studies will experimentally confirm the role of identified genes in virulence and their possible anti-virulence intervention potential.

Occurrence and assessment of antibiotic resistance and virulence of Enterococcus spp. strains isolated from fecal samples of wild animals

About 60% of the etiological agents of human infections are of animal origin, and the microorganisms causing them can be isolated not only from farmed and domestic animals, but also from wildlife. Enterococcus spp. may exhibit intrinsic or acquired resistance to many antibiotic groups, posing significant therapeutic challenges. The aim of this study was to identify and assess the antibiotic resistance and virulence genes of Enterococcus strains isolated from fecal samples of wild animals. The 118 strains were obtained from deer (n = 38), wild boar (n = 29), hare (n = 19), roe deer (n = 12), fallow deer (n = 5), raccoon dog (n = 4), fox (n = 4), moose (n = 2), polecat (n = 2), rabbit (n = 1), wolf (n = 1) and marten (n = 1). Antibiotic resistance assessments were performed using the disk diffusion method following the recommendations of the European Committee on Antimicrobial Susceptibility Testing (EUCAST). The frequency of occurrence of vancomycin-resistant enterococci (VRE) phenotypes, high-level streptomycin resistance (HLSR), high-level gentamicin resistance (HLGR), and high-level aminoglycoside resistance (HLAR) was also determined. The PCR was used to detect virulence genes (VGs) (agg, gelE, EfaAfs, ace, pil, ebpA, ebpB, ebpC, srtA, hyl, asa, cylA and cylB). The study revealed a high species diversity of Enterococcus spp. Among the 118 strains collected, 70 were resistant to at least one antibiotic. The majority of strains exhibited resistance to eravacycline, while the least resistance was observed against ampicillin. Strains with VRE, HLSR, HLGR, and HLAR phenotypes were identified. Multidrug resistant (MDR) strains were detected. However, extensively drug-resistant (XDR) and pandrug-resistant (PDR) strains were not observed. The virulence factors were present in the tested strains, and the most frequently detected gene was agg encoding aggregation substance. We have provided evidence that healthy wild animals can be reservoirs of pathogenic Enterococcus strains, including MDR strains and with many VGs, which can be transmitted to humans.

Microbiota mechanisms in cancer progression and therapy

The composition of the microbiota in patients has been shown to correlate with cancer progression and response to therapy, highlighting unique opportunities to improve patient outcomes. In this review, we discuss the challenges and advancements in understanding the chemical mechanisms of specific microbiota species, pathways, and molecules involved in cancer progression and treatment. We also describe the modulation of cancer and immunotherapy by the microbiota, along with approaches for investigating microbiota enzymes and metabolites. Elucidating these specific microbiota mechanisms and molecules should offer new opportunities for developing enhanced diagnostics and therapeutics to improve outcomes for cancer patients. Nonetheless, many microbiota mechanisms remain to be determined and require innovative chemical genetic approaches.

Staphylococcus aureus Endocarditis Immunothrombosis

Background: Infective endocarditis continues to represent a challenge for healthcare systems, requiring careful management and resources. Recent studies have indicated a shift in the predominant pathogens of concern, with Streptococcus sp. a being superseded by Staphylococcus sp. and Enterococcus sp. as the leading causes of concern. This shift is of concern as it is associated with Staphylococcus Aureus which has a high virulence rate and a tendency to form a biofilm, meaning that non-surgical therapy may not be effective. It is imperative to deliberate on the likelihood of platelet blood clot formation, which may be accompanied by bacterial infestation and the development of a biofilm. Methods: MEDLINE, Embase, and Pubmed were searched using terms relating to 'endocarditis' and 'Staphilococcus aureus', along with 'epidemiology', 'pathogenesis', 'coagulation', 'platelet', 'aggregation', and 'immunity'. The search focused on publications from the past 15 years, but excluded older, highly regarded articles. We also searched the reference lists of relevant articles. Recommended review articles are cited for more details. Results: An endocarditis lesion is believed to be a blood clot infected with bacteria that adheres to the heart valves. Infective endocarditis is a good example of immunothrombosis, where the coagulation system, innate immunity and the function of coagulation in isolating and eliminating pathogens interact. However, in the context of infective endocarditis, immunothrombosis unintentionally establishes an environment conducive to bacterial proliferation. The process of immunothrombosis impedes the immune system, enabling bacterial proliferation. The coagulation system plays a pivotal role in the progression of this condition. Conclusion: The coagulation system is key to how bacteria attach to the heart valves, how vegetations develop, and how complications like embolisation and valve dysfunction occur. Staphylococcus aureus, the main cause of infective endocarditis, can change blood clotting, growing well in the fibrin-rich environment of vegetation. The coagulation system is a good target for treating infective endocarditis because of its central role in the disease. But we must be careful, as using blood-thinning medicines in patients with endocarditis can often lead to an increased risk of bleeding.

Medicinal plants: bioactive compounds, biological activities, combating multidrug-resistant microorganisms, and human health benefits - a comprehensive review

In recent years, medicinal plants have gained significant attention in modern medicine due to their accessibility, affordability, widespread acceptance, and safety, making herbal remedies highly valued globally. Consequently, ensuring medicinal plants' quality, efficacy, and safety has become a critical concern for developed and developing nations. The emergence of multidrug-resistant microorganisms poses a serious global health threat, particularly in low-income regions, despite significant advancements in antimicrobial drugs and medical research over the past century. The rapid spread of these multidrug-resistant infections is primarily attributed to improper prescriptions, overuse, and unregulated access to antibiotics. Addressing these challenges, the standardization of plant-derived pharmaceuticals could pave the way for a transformative era in healthcare. Preserving and leveraging the historical knowledge of medicinal plants is essential before such valuable information is lost. Recently, there has been growing interest among natural and pharmaceutical scientists in exploring medicinal plants as potential sources of antimicrobial agents. This current review aims to identify the most common pathogens threatening human health, analyze the factors contributing to the rise of drug-resistant microorganisms, and evaluate the widespread use of medicinal plants across various countries as alternative antibiotics, highlighting their unique mechanisms of antimicrobial resistance.

Food, Health, and Environmental Impact of Lactic Acid Bacteria: The Superbacteria for Posterity

Lactic acid bacteria (LAB) are Gram-positive cocci or rods that do not produce spores or respire. Their primary function is to ferment carbohydrates and produce lactic acid. The two primary forms of LAB that are currently recognized are homofermentative and heterofermentative. This review discusses the evolutionary diversity and the biochemical and biophysical conditions required by LAB for their metabolism. Next, it concentrates on the applications of these bacteria in gut health, cancer prevention, and overall well-being and food systems. There are numerous uses for LAB, including the food and dairy sectors, as probiotics to improve human and animal gut-health, as anti-carcinogenic agents, and in food safety as biopreservatives, pathogen inhibitors, and reducers of anti-nutrients in foods. The group included many genera, including Aerococcus, Carnobacterium, Enterococcus, Lactobacillus, Lactococcus, Leuconostoc, Streptococcus, Tetragenococcus, Vagococcus, and Weissella. Numerous species of Lactobacillus and Bifidobacterium genera as well as other microbes have been suggested as probiotic strains, or live microorganisms added to meals to improve health. LAB can colonize the intestine and take part in the host's physiological processes. This review briefly highlights the role of these bacteria in food safety and security as well as aspects of regulation and consumer acceptance. Finally, the recent innovations in LAB fermentations and the limitations and challenges of the applications of LAB in the food industry are discussed. Notwithstanding recent developments, the study of LAB and their functional components is still an emerging topic of study that has not yet realized its full potential.

Emergence of transferable daptomycin resistance in Gram-positive bacteria

Daptomycin (DAP) is a last-resort antibiotic to treat infections by multiresistant Gram-positive pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci. DAP resistance and clinical treatment failure has been associated with adaptive chromosomal mutations, but so far not with transmissible resistance traits. Here we report for the first time an acquired DAP-R determinant (named drc) that we detected in a livestock-associated Mammaliicoccus sciuri isolate. drc consists of a two-gene operon (drcAB) that is controlled by an adjacent two-component system (drcRS). The DrcAB proteins, which mediate DAP inactivation, are similar to BceAB-like antimicrobial peptide transporters of Gram-positives, but are distinct from currently known systems. The mobile drc locus is functional in various bacterial backgrounds, including MRSA. It circulates primarily among Gram-positives in the environment, but also in commensal staphylococci and enterococci, suggesting a risk of transmission into pathogens and emphasizing the importance of low and apathogenic microorganisms as resistance gene reservoirs.

A novel thermostable lytic phage vB_EF_Enf3_CCASU-2024-3 against clinical Enterococcus faecium and Enterococcus faecalis

Enterococci, Gram-positive bacteria, have become a major concern in healthcare settings due to their significant virulence and antibiotic resistance. This research focuses on isolating, phenotypic, and genotypic analysis of enterococci-specific lytic phages to be used as potential candidates in combating multidrug-resistant (MDR) Enterococcus clinical isolates. The virulence of Enterococcus isolates was analyzed by testing for gelatinase and biofilm formation. The phage(s) was isolated from a sewage sample, then purified, propagated, and physiochemically analyzed. The phage was examined using transmission electron microscopy, and the whole genome sequence (WGS) was performed. Sixety-five clinical enterococci including, 27 (41.5%), 33 (50.7%) 3 (4.6%), and 2 (3%) E. faecalis, E. faecium, E. avium, and E. durans, respectively were isolated. Linezolid, teicoplanin, chloramphenicol, and vancomycin exhibited the lowest resistance. Twenty-five (38.5%) isolates were both gelatinase- and biofilm-producers. A novel lytic vB_EF_Enf3 phage belonging to Caudoviricetes class, characterized by an icosahedral head with a diameter of 100 ± 5 nm and a tail measuring 70 ± 5 nm in length was isolated. The phage demonstrated good thermal stability, and viability across various pH levels and exhibited a broad- spectrum of activity against E. faecium and E. faecalis. The vB_EF_Enf3 phage (36,202 bp length) harbored 36 open reading frames (ORFs) with a GC content of 34.4% (GenBank accession, PP747318). In conclusion, a novel thermostable lytic bacteriophage vB_EF_Enf3, belonging to class Caudoviricetes, was isolated from sewage showing broad-spectrum potent lytic activity against E. faecium and E. faecalis and maintained stability under various extreme conditions, including temperature, and pH fluctuations.

Genomic Characterization of Enterococcus casseliflavus Isolated from Beef Cows and Calves

Enterococcus species are used as One Health indicators of antimicrobial resistance (AMR) in humans, animals, and the environment. A surveillance study in beef cows and calves isolated Enterococcus casseliflavus along with E. faecium, E. faecalis, and E. hirae. Given the high prevalence of E. casseliflavus, we elected to characterize this species to better understand its role in the antimicrobial resistance of enterococci in cows and calves. Almost 12% of E. casseliflavus isolates exhibited multidrug resistance with the majority being resistant to lincomycin (99%), followed by quinupristin-dalfopristin (34%), ciprofloxacin (9.6%), tylosin (4.5%), erythromycin (2.7%), tetracycline (1.8%), tigecycline (1.5%), daptomycin (0.6%), streptomycin (0.3%), and kanamycin (0.3%). All E. casseliflavus were susceptible to chloramphenicol, penicillin, streptomycin, nitrofurantoin, gentamicin, and linezolid. Whole genome antimicrobial resistance gene profiling identified vanC-type intrinsic vancomycin resistance genes in all E. casseliflavus, with the vanC4XYT gene cluster being dominant (67%) followed by vanC2XYT (31%) and vanC3XYT (1.5%). Resistance genes for erythromycin (ermB) and tetracycline (tetM) were rarely identified (2.1% and 1.2%, respectively) within E. casseliflavus genomes. No resistance genes were identified to explain either the quinupristin-dalfopristin or ciprofloxacin resistance in these isolates. A core genome phylogenetic tree revealed two clades that exhibited no distinct association with the age of the host, time of sample collection, or the farm sampled. The open nature of the E. casseliflavus pan-genome highlighted its intraspecies diversity. These findings suggest that E. casseliflavus is likely a low-risk species in terms of contributing to antimicrobial resistance in the cow-calf sector.

Tetracyclines at subinhibitory concentrations are lethal for NADH peroxidase-deficient mutants of Enterococcus faecium

OBJECTIVES

Tigecycline is a bacteriostatic antibiotic member of the glycylcycline family that inhibits protein synthesis. Tigecycline is a last-line treatment for infections caused by MDR pathogens like vancomycin-resistant Enterococcus faecium (VR-Efm). We recently explored oxidative stress defences in E. faecium and we here aimed to assess their role in antibiotic resistance.

METHODS

Antibiotic susceptibility was evaluated in mutants deficient in primary oxidative stress defences by monitoring bacterial survival after a 24 h treatment. Hydrogen peroxide (H2O2) levels were quantified to link bacterial survival to oxidative stress.

RESULTS

Unexpectedly, tigecycline and other tetracyclines were lethal for VR-Efm AUS0004 mutants deficient in NADH peroxidase (Npr) at concentrations below their MICs. Lethality seemed to correlate with increased H2O2 accumulation in the Δnpr mutant. H2O2 production in Efm AUS0004 was mainly mediated by lactate oxidase Lox1, whereas Lox2 and pyruvate oxidase (Pox) had minor or no roles. Tigecycline was not lethal for a ΔnprΔlox1 double mutant, suggesting lethality results from both antibiotic effect and peroxide accumulation.

CONCLUSIONS

This study might pave the way to develop strategies aimed at potentiating tigecycline action by increasing endogenous H2O2 production and/or impairing H2O2 detoxification, potentially improving treatment efficiencies for VR-Efm infections with this last-line antibiotic.

Global trends in antimicrobial resistance of Enterococcus faecium: a systematic review and meta-analysis of clinical isolates

Background

Multidrug-resistant bacteria are associated with a high number of deaths and pose a significant global concern. In recent decades, among these resistant bacteria, Enterococcus faecium, a hospital-acquired pathogen, has attracted more attention.

Objective

The present study aims to document the current state of resistance in E. faecium globally by considering several variables, including geographical locations, temporal trends, and sources of infection.

Methods

We searched studies in PubMed, Scopus, and Web of Science (30 November 2022). All statistical analyses were carried out using the statistical package R.

Results

Our meta-analysis of antibiotic resistance across various clinical isolates revealed substantial heterogeneity and variability. The average resistance proportions ranged from 2% for linezolid to 62.8% for erythromycin, with significant differences observed across different time periods, countries, and World Health Organization regional offices.

Conclusion

Our findings confirm the high antibacterial activity of linezolid against E. faecium isolates. Additionally, our investigation reveals a gradual increase and a concerning upward trend in resistance rates for nearly all agents in recent years. However, the significant reduction in resistance rates for certain antibiotics suggests that these drugs could potentially regain their effectiveness in the future.

Description of an Enterococcus faecium genotype vanB outbreak in a hospitalization ward

BACKGROUND AND OBJECTIVES

Vancomycin-resistant Enterococcus faecium (VRE) infections have increased in the last years. Hospital outbreaks have been described with a challenging microbiological diagnosis and control of the transmission.

METHODS

This is a prospective study of a nosocomial outbreak of VRE in a conventional hospitalization ward. Three clinical samples of VRE genotype vanB (vanB VRE) were detected in two surgical wards. Epidemiological control measures were implemented, including contact isolation, patients from clean surgery ward transferred to other wards, staff training, weekly screening with rectal swab and environmental study.

RESULTS

In a 3-month follow-up period, rectal screening was performed on a total of 314 patients, being positive for vanB VRE 51 patients (16.2%). A study of the surface of the common areas with exclusive use by healthcare personnel detected vanB VRE in 28% of the samples. All the strains of VRE analyzed by MLST were ST117, which belongs to clonal complex 17. Hand hygiene observations show proper adherence in 56% of the events monitored. Notwithstanding the large number of colonized patients, just one patient had a relevant infection requiring treatment, with good evolution.

CONCLUSIONS

The survival of VRE on surfaces and the poor adherence to hand hygiene might have contributed to repetitively infect surfaces, perpetuating the outbreak. After 10 months without positive clinical samples, it was decided to suspend the screening, even though there were still screening positive results. Despite its spread, the clinical impact was low, possibly because the outbreak took place in a ward without severe immunosuppressed patients. The frequent isolation of VRE on surfaces which were exclusive from healthcare personnel areas, indicates how important is the disinfection of these areas.

Development and Application of Optimized Isolation Methods and Diagnostic PCR Protocols for the Detection of Pathogenic Enterococcus cecorum Isolated from Broiler Chickens

Enterococcus cecorum (EC) is a dominant enteric commensal in broiler chickens. However, pathogenic strains of EC cause increased morbidity and mortality from septicemic disease in broiler production worldwide. EC infections can present as pericarditis and paralytic spinal lesions from which pathogenic EC can be isolated. However, the inability to distinguish between commensal and pathogenic EC strains has confounded the search for the source of pathogenic EC in environmental or hatchery samples. This issue is exacerbated by poor sensitivity of standard sampling and culture methods. Comparative genomic analysis of EC isolates previously identified a conserved capsule region in pathogenic EC strains that is absent or variable in commensal strains. Based on a capsular synthesis gene, cpsO, and EC species-specific sodA primers, we designed a standard multiplex PCR to distinguish pathogenic EC from commensal EC strains. To allow for increased sample throughput, a real-time PCR protocol was developed in tandem based on detection of these genes. To increase the culture sensitivity, a selective enrichment protocol using Todd-Hewitt Broth with 1% yeast extract and four antibiotics enabled the isolation of pathogenic EC from egg transfer residue and culled eggs at hatcheries. Pulsed-field gel electrophoresis was used to genotype recovered hatchery isolates, which identified clonal pathogenic EC strains isolated from hatchery residue and a spinal lesion of a broiler. The ability to distinguish pathogenic EC from commensal EC coupled with modified culture methods will facilitate improved surveillance of pathogenic EC throughout broiler production, ideally leading to decreased incidence or eradication of this disease.

Postoperative delirium after cardiac surgery associated with perioperative gut microbiota dysbiosis: Evidence from human and antibiotic-treated mouse model

BACKGROUND

Research links gut microbiota to postoperative delirium (POD) through the gut-brain axis. However, changes in gut microbiota and fecal short-chain fatty acids (SCFAs) in POD patients during the perioperative period and their association with POD are unclear.

METHODS

We conducted a nested case-control study among patients undergoing off-pump coronary artery bypass grafting, focusing on POD as the main outcome. POD patients were matched 1:1 with non-POD patients based on sociodemographic characteristics, health, and diet. Fecal samples were collected pre- and post-surgery to assess gut microbiota and SCFAs changes. Postoperative fecal samples were transplanted into antibiotic-treated mice to evaluate delirium-like behavior and neuroinflammation.

RESULTS

Out of 120 patients, 60 were matched. Before surgery, gut microbiota in both groups was similar. After surgery, POD patients had lower alpha diversity and distinct microbiota compared to non-POD patients. LEfSe analysis showed POD was linked to increased opportunistic pathogens (Enterococcus) and decreased SCFAs producers (Bacteroides, Ruminococcus, etc.). SCFAs were significantly reduced in POD patients and negatively correlated with delirium severity and plasma inflammation. Mice receiving fecal transplants from POD patients exhibited delirium-like behavior and neuroinflammation.

CONCLUSIONS

Postoperative delirium is associated with gut microbiota dysbiosis, marked by an increase in opportunistic pathogens and a decrease in SCFA-producing genera.

REGISTRATION

Chinese Clinical Trial Registry ChiCTR2300070477.

Review of Enterococcus faecalis Infections of Poultry

Enterococcus faecalis organisms are Gram-positive cocci that are ubiquitous in the environment, occurring in water and soil, and are commensal inhabitants of the intestinal tracts of both vertebrate and invertebrate animals. They are considered opportunists and possess many virulence-encoding traits, including the formation of biofilms and toxins. Enterococcus faecalis produces cytolysin, which is a unique toxin having activity against both eukaryotic and prokaryotic cells. Cytolysin causes hemolysis of red blood cells and has also been termed hemolysin. Enterococcus faecalis organisms are intrinsically resistant to some antibiotics and can transmit antimicrobial resistance to other microorganisms. In poultry, there is ample evidence to indicate that E. faecalis can be egg transmitted, causing decreased hatchability of eggs. Enterococcus faecalis has been found to rapidly spread among hatchlings that are exposed in the hatcher. In older birds, some E. faecalis isolates cause amyloid arthropathy. Various methods have been developed to assess E. faecalis isolates for virulence-encoding traits, including Multilocus sequence typing and embryo lethality assays. However, much variability occurs in interpreting the results of these methods and the correlation between genotypes, phenotypes, and virulence has not been well established. The virulence traits and pathogenesis of E. faecalis in poultry need to be elucidated further.

Insights into ecology, pathogenesis, and biofilm formation of Enterococcus faecalis from functional genomics

SUMMARYEnterococcus faecalis is a significant resident of the gastrointestinal tract of most animals, including humans. Although generally non-pathogenic in healthy hosts, this microbe is adept at the exploitation of compromises in host immune functions, resulting in life-threatening opportunistic infections whose treatments are complicated by a high degree of intrinsic and acquired resistance to antimicrobial chemotherapy. Historically, progress in enterococcal research was limited by a lack of experimental models that replicate natural infection pathways and the relevance of in vitro studies to the natural biology of the organism. In this review, we summarize the history of enterococcal research during the 20th and early 21st centuries and describe more recent genetic and genomic tools and screens developed to address challenges in the field. We also describe how the results of recent studies reveal the importance of previously uncharacterized enterococcal genes, and we provide examples of interesting determinants that have emerged as important contributors to enterococcal biology. These factors may also serve as targets for future vaccines and chemotherapeutic agents to combat life-threatening hospital infections.

Lasso peptides sviceucin and siamycin I exhibit anti-virulence activity and restore vancomycin effectiveness in vancomycin-resistant pathogens

Antibiotic resistance is a major threat to human health and new drugs are urgently needed. Ideally, these drugs should have several cellular targets in pathogens, decreasing the risk of resistance development. We show here that two natural ribosomally synthesized lasso peptides (LPs), sviceucin and siamycin I, (1) abolish bacterial virulence of pathogenic enterococci, (2) restore vancomycin clinical susceptibility of vancomycin-resistant (VR) enterococci in vitro and in a surrogate animal model, and (3) re-sensitize VR Staphylococcus aureus. Mode of action (MoA) analyses showed that they do so by inhibiting the histidine kinases (HKs) FsrC and VanS controlling these phenotypes. Strains resistant to the vancomycin/LP combination were difficult to obtain, and were still fully susceptible to the anti-virulence effect of the LPs, highlighting the advantage of multiple targets. Together with the highly sought-after MoA as HK inhibitors, such properties make these lasso peptides promising candidates for the development of next generation antibiotics.

The Evolving Landscape of Infective Endocarditis: Difficult-to-Treat Resistance Bacteria and Novel Diagnostics at the Foreground

Infective endocarditis (IE) is a relatively rare but potentially life-threatening disease characterized by substantial mortality and long-term sequelae among the survivors. In recent decades, a dramatic change in the profile of patients diagnosed with IE has been observed primarily in developed countries, most likely due to an aging population and a recent increase in invasive medical procedures. Nowadays, the typical IE patient is usually older, with complex comorbidities, and a history significant for cardiac disease, including degenerative heart valve disease, prosthetic valves, or cardiovascular implantable electronic devices (CIEDs). Moreover, as patient risk factors change, predisposing them to more healthcare-associated IE, the microbiology of IE is also shifting; there are growing concerns regarding the rise in the incidence of IE caused by difficult-to-treat resistance (DTR) bacteria in at-risk patients with frequent healthcare contact. The present review aims to explore the evolving landscape of IE and summarize the current knowledge on novel diagnostics to ensure timely diagnosis and outline optimal therapy for DTR bacterial IE.

Vancomycin-Resistant Enterococci: Screening Efficacy and the Risk of Bloodstream Infections in a Specialized Healthcare Setting

Background: Vancomycin-resistant enterococci (VRE) rectal colonization represents a critical risk factor for subsequent bloodstream infections (BSIs), posing a serious concern in healthcare settings. This study aims to investigate the association between the presence of VRE in rectal swabs and the occurrence of BSIs, highlighting the challenges of rapid detection and patient care implications in an infectious disease hospital setting. Methods: We performed a retrospective analysis of cultural rectal swab screening and molecular assays (MAs) for VRE detection between January 2020 and December 2023. All adult patients admitted with at least one rectal swab screening performed during hospitalization were included. All blood cultures that yielded VRE were identified, and the first Enterococcus-positive blood sample for each patient with at least one prior rectal swab per year was analyzed. Results: The results showed a 15.4% positivity rate for VRE in cultural screening, predominantly Enterococcus faecium. MA showed a higher prevalence of 49.4%, with a significant discordance between MA rectal swab screening and cultural testing. Patients with VRE intestinal colonization by E. faecium were significantly more likely to develop E. faecium BSI, with a risk ratio of 9.78 (p < 0.001). Conclusions: The study identified a strong correlation between VRE rectal colonization and the risk of developing BSI, emphasizing the need for effective screening and infection control measures. The results support the inclusion of molecular testing in VRE detection protocols and highlight the importance of ongoing surveillance for antimicrobial resistance.

Investigating the phytochemical profile, biological potentials, morphological, and anatomical characteristics of Cyclotrichium origanifolium (Labill.) Manden. & Scheng. (Lamiaceae) from Turkey

Cyclotrichium origanifolium, a plant widely used in Eastern and Southern Anatolia for culinary purposes, was subject of this study, which aimed to comprehensively evaluate its potential therapeutic applications. This research stands out due to its holistic approach, combining morpho-anatomical studies, chemical, and biological analyses to explore antioxidant, antidiabetic, anticholinesterase, genotoxic, and anti-genotoxic effects of methanolic and aqueous extracts, as well as flowering aerial part essential oil. It is a perennial plant, typically ranging from 10 to 40 cm in height, with a suffrutescent and highly branched growth habit. Essential oils are produced within glandular trichomes. Oil, analyzed via GC-MS/MS, revealed 24 compounds accounting for 96.4% of oil, with isomenthone (52.4%), pulegone (23.4%), and β-pinene (9.5%) as predominant components. These findings are significant as they provide new insights into chemical composition of oils, particularly highlighting pharmacologically active compounds. Methanol extract exhibited superior antioxidant activity, correlated with high phenol and tannin content. Essential oil showed moderate inhibition of α-amylase (49.54%) and mild inhibition of acetylcholinesterase (11.84%) and butyrylcholinesterase (16.93%), suggesting potential in managing oxidative stress and neurodegenerative diseases. Study also conducted biosafety evaluations using Ames/Salmonella and Allium tests, essential for assessing genotoxic and antigenotoxic potential of natural products. Notably, significant antimicrobial effects were identified, particularly against Pseudomonas aeruginosa and Enterococcus faecalis. Comprehensive analysis and discovery of significant bioactivities position this research as a valuable contribution to field, distinguishing it from previous studies on similar species. This study provides a foundational understanding of morpho-anatomical, pharmacological, biological properties of plant, opening avenues for future research.

Antibacterial and antibiofilm potential of Thuja orientalis L. extract targeting cariogenic Enterococcus faecalis ATCC 29212: A combined in-vitro, in-silico study, and cytotoxicity screening

OBJECTIVES

In this study, we explored the efficacy of methanolic extract of Thuja orientalis (TOME) as a novel antibacterial and antibiofilm agent against a cariogenic bacterium, Enterococcus faecalis ATCC 29212.

DESIGN

Antibacterial susceptibility studies were conducted and surface morphology analysis was performed using field emission scanning electron microscopy (FESEM). Antibiofilm activity was evaluated through both qualitative and quantitative biofilm inhibition assays and validated by microscopic analysis. In-silico molecular docking studies were conducted using the EDock server. The effectiveness of TOME was substantiated by biofilm model on dentin discs and cytotoxicity towards the HaCaT cell line was assessed using the MTT assay.

RESULTS

TOME exhibited significant bactericidal activity with minimum inhibitory concentration of 12.5 mg/mL and additionally, it effectively compromised bacterial cell wall integrity. Qualitative, quantitative and microscopic studies depicted the inhibition of biofilm formation. TOME significantly impacted the production of extracellular polymeric substance and extracellular DNA. Molecular docking studies identified beta-caryophyllene as a potent inhibitor of the Enterococcal surface protein (Esp). Biofilm model depicted the reduction of bacterial load on dentin discs. Additionally, TOME showed reduced cytotoxicity on HaCaT cells, indicating its potential as a safe therapeutic agent.

CONCLUSION

These findings highlight TOME's promise for developing novel treatments for dental infections and biofilm-associated diseases. Further research should focus on isolating and characterizing the active compounds within TOME, particularly beta-caryophyllene, to elucidate their precise mechanisms of action.

Vancomycin-resistant Enterococcus (VRE) isolates from dogs and cats in veterinary hospitals in Brazil

BACKGROUND

In veterinary medicine, particularly concerning dogs and cats, there is limited data regarding vancomycin-resistant Enterococcus (VRE). However, multidrug-resistant Enterococcus is frequently identified, raising concerns about the potential for spreading these resistant microorganisms to humans due to their zoonotic nature. This study aimed to identify VRE colonizing animals admitted to a veterinary hospital and to determine the presence of the major resistance genes responsible for vancomycin resistance.

RESULTS

Enterococcus was found to carry the vanA gene in 52.54% of cases, the vanB gene in 23.73%, the vanC gene in 20.34%, and the vanE gene in 3.39%. The antimicrobials with the lowest resistance were chloramphenicol (5.08%) and ampicillin (6.78%). In contrast, the highest resistance was observed with enrofloxacin (79.66%), rifampicin (67.80%), and ciprofloxacin (61.02%). Seven Enterococcus isolates showed resistance to vancomycin as well as high-level aminoglycoside resistance (HLAR).

CONCLUSION

A total of 46 animals were found to be colonized by VRE, of which 16 were healthy. The vanA gene was the most commonly isolated (52.54%), followed by vanB (23.73%), vanC (20.34%), and vanE (3.39%). This represents the first report of the vanE gene being identified in a dog in Brazil. Among the 59 Enterococcus isolates, 84.75% (n = 50) were found to be multidrug resistant. The colonization of VRE and Enterococcus HLAR in dogs and cats poses a public health concern, as it increases the risk of environmental dissemination and has implications for One Health.

Gut Dysbiosis Exacerbates Intestinal Absorption of Cadmium and Arsenic from Cocontaminated Rice in Mice Due to Impaired Intestinal Barrier Functions

Globally, humans face gut microbiota dysbiosis; however, its impact on the bioavailability of cadmium (Cd) and arsenic (As) from rice consumption─a major source of human exposure to these metals─remains unclear. In this study, we compared Cd and As accumulation in the liver and kidneys of mice with disrupted gut microbiota (administered cefoperazone sodium), restored microbiota (administered probiotics and prebiotics following antibiotic exposure), and normal microbiota, all after consuming cocontaminated rice. Compared to normal mice, microbiota-disrupted mice exhibited 30.9-119% and 30.0-100% (p < 0.05) higher Cd and As levels in tissues after a 3 week exposure period. The increased Cd and As bioavailability was not due to changes in the duodenal expression of Cd-related transporters or As speciation biotransformation in the intestine. Instead, it was primarily attributed to a damaged mucus layer and depleted tight junctions associated with gut dysbiosis, which increased intestinal permeability. These mechanisms were confirmed by observing 34.3-74.3% and 25.0-75.0% (p < 0.05) lower Cd and As levels in the tissues of microbiota-restored mice with rebuilt intestinal barrier functions. This study enhances our understanding of the increased risk of dietary metal(loid) exposure in individuals with gut microbiota dysbiosis due to impaired intestinal barrier functions.

Plasma cell-free DNA Droplet Digital PCR provides rapid and efficient infectious microbiology diagnosis for febrile haematological patients

Background

Febrile haematological patients are at high risk for potential bloodstream infections, the rapid and accurate identification of pathogens is crucial for clinical diagnosis and treatment. Droplet Digital PCR (ddPCR) is a novel and ultra-sensitively molecular technique for the rapid detection of pathogens. We evaluated the ability of ddPCR to identify infectious etiologies to discuss the applicability of ddPCR in the diagnosis and treatment of infections for febrile haematological patients.

Methods

This study enrolled and analyzed 89 ddPCR tests performed on 71 febrile haematological patients. We conducted a comparison between ddPCR results, blood culture (BC), and conventional microbiological testing (CMT). Additionally, we analyzed the correlation between ddPCR results and inflammatory factors, as well as their impact on antimicrobial therapy.

Results

DdPCR detected 113 pathogens in 72 plasma samples, while CMT identified 39 pathogens in 32 plasma samples. The detection rate of bacteria and viruses using ddPCR was significantly higher than that of CMT (p <0.0001). The turnaround time (TAT) for pathogenic diagnosis was significantly shorter with ddPCR compared to CMT (p <0.0001). When we used the CMT as reference standard, the sensitivity and specificity of ddPCR were 93.8%, 26.3%, respectively. We observed a positive correlation between the ddPCR results and CRP, PCT and IL-6, and ddPCR (AUC=0.771) has better diagnostic performance. The anti-infective treatment strategies were adjusted for 30 patients based on the positive ddPCR results, with 86.7% (26/30) of these cases demonstrating effectiveness in the anti-infective treatment.

Conclusion

DdPCR has the potential to enhance pathogen detection in febrile haematological patients by offering high sensitivity, rapid, precise results, it demonstrates better diagnostic performance compared to inflammatory factors and can contribute to the real-time clinical optimization of antimicrobial regimens, thereby enhancing the efficacy of anti-infective therapy.

Multi-omic signatures of host response associated with presence, type, and outcome of enterococcal bacteremia

Despite the prevalence and severity of enterococcal bacteremia (EcB), the mechanisms underlying systemic host responses to the disease remain unclear. Here, we present an extensive study that profiles molecular differences in plasma from EcB patients using an unbiased multi-omics approach. We performed shotgun proteomics and metabolomics on 105 plasma samples, including those from EcB patients and healthy volunteers. Comparison between healthy volunteer and EcB-infected patient samples revealed significant disparities in proteins and metabolites involved in the acute phase response, inflammatory processes, and cholestasis. Several features distinguish these two groups with remarkable accuracy. Cross-referencing EcB signatures with those of Staphylococcus aureus bacteremia revealed shared reductions in cholesterol metabolism proteins and differing responses in platelet alpha granule and neutrophil-associated proteins. Characterization of Enterococcus isolates derived from patients facilitated a nuanced comparison between EcB caused by Enterococcus faecalis and Enterococcus faecium, uncovering reduced immunoglobulin abundances in E. faecium cases and features capable of distinguishing the underlying microbe. Leveraging extensive patient metadata, we now have identified features associated with mortality or survival, revealing significant multi-omic differences and pinpointing histidine-rich glycoprotein and fetuin-B as features capable of distinguishing survival status with excellent accuracy. Altogether, this study aims to culminate in the creation of objective risk stratification algorithms-a pivotal step toward enhancing patient management and care. To facilitate the exploration of this rich data source, we provide a user-friendly interface at https://gonzalezlab.shinyapps.io/EcB_multiomics/.

IMPORTANCE

Enterococcus infections have emerged as the second most common nosocomial infection, with enterococcal bacteremia (EcB) contributing to thousands of patient deaths annually. To address a lack of detailed understanding regarding the specific systemic response to EcB, we conducted a comprehensive multi-omic evaluation of the systemic host response observed in patient plasma. Our findings reveal significant features in the metabolome and proteome associated with the presence of infection, species differences, and survival outcome. We identified features capable of discriminating EcB infection from healthy states and survival from mortality with excellent accuracy, suggesting potential practical clinical utility. However, our study also established that systemic features to distinguish Enterococcus faecalis from Enterococcus faecium EcB show only a moderate degree of discriminatory accuracy, unlikely to significantly improve upon current diagnostic methods. Comparisons of differences in the plasma proteome relative to healthy samples between bacteremia caused by Enterococcus and Staphylococcus aureus suggest the presence of bacteria-specific responses alongside conserved inflammatory reactions.

Vitamin B6 Alleviates Aflatoxin B1-Induced Impairment of Testis Development by Activating the PI3K/Akt Signaling Pathway

Aflatoxin B1 (AFB1) is a harmful environmental contaminant known to disrupt gut microbiota and cause health problems. In recent years, the role of vitamin B6 (VB6) in maintaining intestinal and reproductive health has attracted much attention. AFB1 has been found to damage the intestinal barrier and cause inflammation by disrupting the intestinal microbiota, particularly by increasing the abundance of Enterococcus. In mice treated with AFB1, serum metabolites were disturbed, VB6 serum levels were reduced, and testicular inflammation was exacerbated. Enterococcus exposure in mice leads to a reduction in serum VB6 levels, which is accompanied by intestinal and testicular damage. However, VB6 supplementation significantly ameliorated AFB1-induced intestinal and testicular injury. Transcriptomics and Western blotting showed that after AFB1 exposure, VB6 could increase the expression of phosphoinositide 3-kinase (PI3K) and kinase B (AKT) as well as their phosphorylated forms in the testes of mice. Based on the results, AFB1 leads to intestinal and testicular damage by disturbing the gut microbiota, and VB6 represents a potential therapeutic to counteract this damage. In conclusion, supplementation with adequate VB6 can ameliorate AFB1-induced intestinal and testicular damage, emphasizing the importance of VB6 intervention and providing a new perspective for the prevention and treatment of AFB1-related health issues.

An Insight into the Presence of Antimicrobial Resistance Genes in Opportunistic Pathogenic Bacteria Isolated from Farm-Reared Crickets

To support the role of insects as sustainable feed and food ingredients, evaluating their potential microbiological risk and safety is crucial. In this study, we investigated the presence of antimicrobial resistance (AMR) genes in selected live opportunistic pathogenic bacteria isolated during the rearing process from clinically healthy farm-reared crickets. Molecular analysis was performed by wholegenome sequencing of a total of 14 of these bacterial strains, 7 from house crickets (Acheta domesticus) and 7 from banded crickets (Gryllodes sigillatus), belonging to Enterobacteriaceae, Staphylococcaceae, Enterococcaceae, and Bacillaceae families. The β-lactam AMR genes (blaOXY2-6, blaACT-16, and blaSHV variants) were the most predominant genes identified, mainly in Enterobacteriaceae strains and in association with fosfomycin (fosA) and oqxAB efflux pump complexes. In addition, blaZ and mecA genes were detected in Bacillus cereus and Mammaliicoccus sciuri strains isolated from both insect species. Genetic mobile elements including IncFIA, IncFIB, IncHI1A, IncHI1B, rep13, and Col3M-like plasmids were detected in Klebsiella pneumoniae, Enterobacter hormaechei, Staphylococcus arlettae, and B. cereus, respectively. The results indicate that, not only in the final product but also during the insect-rearing process, microbial safety control, regarding the presence of pathogenic bacteria and AMR genes, is essential for effectively decreasing the microbiological risk between cricket batches within their environment and in terms of the related feed and food chain.

N-terminal domain swapping: A new paradigm for spermidine/spermine N-acetyltransferase (SSAT) protein structures?

Enterococcus faecalis is a multi-drug-resistant human pathogen that is found in a variety of environments and is challenging to treat. Under stress conditions, some bacteria regulate intracellular polyamine concentrations via polyamine acetyltransferases to reduce their toxicity. The E. faecalis genome encodes two polyamine acetyltransferases: PmvE and BltD. Both of these proteins belong to the Gcn5-related N-acetyltransferase (GNAT) superfamily. It is unclear why there are two enzymes with similar substrate specificities in this organism. To better understand the structure/function relationship of the E. faecalis BltD enzyme, we determined its crystal structure and performed additional assays to explore its oligomeric state and enzymatic activity. The goal was to determine whether there were structural or catalytic differences between this enzyme and other polyamine acetyltransferases that could explain this redundancy and be exploited for future development of targeted inhibitors for this important human pathogen. We found the BltD enzyme was structurally unique due to its N-terminal domain swapped dimer. However, this enzyme adopts a catalytically active monomer rather than dimer in solution. This indicates the crystal structure we obtained may represent a state that forms at high protein and salt concentrations and at low pH used during crystallization. The BltD dimer found in the crystal may represent a unique view of how an inhibitory peptide or molecule could be designed to occupy its active site. Additionally, this structure shows the extensive flexibility of the N-terminal portion of the E. faecalis BltD enzyme.

Antimicrobial Resistance Characteristics of Fecal Escherichia coli and Enterococcus Species in U.S. Goats: 2019 National Animal Health Monitoring System Enteric Study

Escherichia coli and Enterococcus species are normal bacteria of the gastrointestinal tract and serve as indicator organisms for the epidemiology and emergence of antimicrobial resistance in their hosts and the environment. Some E. coli serovars, including E. coli O157:H7, are important human pathogens, although reservoir species such as goats remain asymptomatic. We describe the prevalence and antimicrobial resistance of generic E. coli, E. coli O157:H7, and Enterococcus species collected from a national surveillance study of goat feces as part of the National Animal Health Monitoring System (NAHMS) Goat 2019 study. Fecal samples were collected from 4918 goats on 332 operations across the United States. Expectedly, a high prevalence of E. coli (98.7%, 4850/4915) and Enterococcus species (94.8%, 4662/4918) was found. E. coli O157:H7 prevalence was low (0.2%; 10/4918). E. coli isolates, up to three per operation, were evaluated for antimicrobial susceptibility and 84.7% (571/674) were pansusceptible. Multidrug resistance (MDR; ≥3 classes) was uncommon among E. coli, occurring in 8.2% of isolates (55/674). Resistance toward seven antimicrobial classes was observed in a single isolate. Resistance to tetracycline alone (13.6%, 92/674) or to tetracycline, streptomycin, and sulfisoxazole (7.0% 47/674) was the most common pattern. All E. coli O157:H7 isolates were pansusceptible. Enterococcus isolates, up to four per operation, were prioritized by public health importance, including Enterococcus faecium and Enterococcus faecalis and evaluated. Resistance to lincomycin (93.8%, 1232/1313) was most common, with MDR detected in 29.5% (388/1313) of isolates. The combination of ciprofloxacin, lincomycin, and quinupristin resistance (27.1%, 105/388) was the most common pattern detected. Distribution and characteristics of antimicrobial resistance in E. coli and Enterococcus in the U.S. goat population from this study can inform stewardship considerations and public health efforts surrounding goats and their products.

Treatment of Complicated Gram-Positive Bacteremia and Infective Endocarditis

The Gram-positive cocci Staphylococcus aureus, Streptococcus spp., and Enterococcus spp. are the most frequent causative organisms of bloodstream infections and infective endocarditis. "Complicated bacteremia" is a term used in S. aureus bloodstream infections and originally implied the presence of metastatic infectious foci (i.e. complications of S. aureus bacteremia). These complications demand longer antimicrobial treatment durations and, frequently, interventional source control. Several risk factors for the incidence of bacteremia complications have been identified and are often used for the definition of complicated bacteremia. Here, we discuss management and diagnostic approaches and treatment options for patients with complicated bacteremia, with particular focus on infective endocarditis. We also summarize the available evidence regarding imaging modalities and the choice of antimicrobial mono- or combination therapy according to resistance patterns for these pathogens as well as treatment durations and optimized application routes. Finally, we synopsize current and future areas of research in complicated bacteremia and infective endocarditis.

zol and fai: large-scale targeted detection and evolutionary investigation of gene clusters

Many universally and conditionally important genes are genomically aggregated within clusters. Here, we introduce fai and zol, which together enable large-scale comparative analysis of different types of gene clusters and mobile-genetic elements, such as biosynthetic gene clusters (BGCs) or viruses. Fundamentally, they overcome a current bottleneck to reliably perform comprehensive orthology inference at large scale across broad taxonomic contexts and thousands of genomes. First, fai allows the identification of orthologous instances of a query gene cluster of interest amongst a database of target genomes. Subsequently, zol enables reliable, context-specific inference of ortholog groups for individual protein-encoding genes across gene cluster instances. In addition, zol performs functional annotation and computes a variety of evolutionary statistics for each inferred ortholog group. Importantly, in comparison to tools for visual exploration of homologous relationships between gene clusters, zol can scale to handle thousands of gene cluster instances and produce detailed reports that are easy to digest. To showcase fai and zol, we apply them for: (i) longitudinal tracking of a virus in metagenomes, (ii) performing population genetic investigations of BGCs for a fungal species, and (iii) uncovering evolutionary trends for a virulence-associated gene cluster across thousands of genomes from a diverse bacterial genus.

A mouse model of immunosuppression facilitates oral Candida albicans biofilms, bacterial dysbiosis and dissemination of infection

Opportunistic pathogens are a major threat to people, especially those with impaired immune systems. Two of the most important microbes in this category are the fungus Candida albicans and Gram-positive bacteria of the genus Enterococcus, which share overlapping niches in the oral cavity, gastrointestinal and urogenital tracts. The clinical importance of oral C. albicans biofilm and its interaction with the host under immunosuppressive conditions remains largely understudied. Here, we used a mouse model of oropharyngeal candidiasis (OPC) with cortisone acetate injection on alternate days and a continuous supply of C. albicans in drinking water for three days, resulting in immunosuppression. Results showed abundant growth of resident oral bacteria and a strong C. albicans biofilm on the tongue consisting of hyphae which damaged papillae, the epidermal layer, and invaded tongue tissue with the accumulation of inflammatory cells as demonstrated by Grocott's methenamine silver and hematoxylin and eosin staining, respectively. The dispersed microbes from the oral biofilm colonized the gastrointestinal (GI) tract and damaged its integrity, disseminating microbes to other organs. Although no visible damage was observed in the kidney and liver, except increased lipid vacuoles in the liver cells, C. albicans was found in the liver homogenate. Intriguingly, we found co-occurrence of Enterococcus faecalis in the tongue, liver, and stool of immunosuppressed control and C. albicans infected organs. Targeted 16S rRNA and ITS2 amplicon sequencing of microbes from the fecal samples of mice confirmed the above results in the stool samples and revealed an inverse correlation of beneficial microbes in the dysbiosis condition. Our study shows that mucosal-oral infection of C. albicans under immunosuppressed conditions causes tissue damage and invasion in local and distant organs; the invasion may be aided by the overgrowth of the resident endogenous Enterobacteriaceae and other members, including the opportunistic pathogen Enterococcus faecalis.

Invasion of pancreatic ductal epithelial cells by Enterococcus faecalis is mediated by fibronectin and enterococcal fibronectin-binding protein A

The poor prognosis of pancreatic cancer is often attributed to difficulties of early detection due to a lack of appropriate risk factors. Previously, we demonstrated the presence of Enterococcus faecalis (E. faecalis) in pancreatic juice and tissues obtained from patients with cancers of the duodeno-pancreato-biliary region, suggesting the possible involvement of this bacterial species in chronic and malignant pancreatic diseases. However, it remains unclear if and how E. faecalis can infect pancreatic ductal cells. In this study, we used immortalized normal human pancreatic ductal epithelial cells (iPDECs) and pancreatic ductal cancer cell lines to demonstrate that E. faecalis adheres to and invades pancreatic ductal lineage epithelial cells. Inhibitors of micropinocytosis or clathrin- or caveolae-mediated endocytosis suppressed iPDEC invasion by E. faecalis. Mechanistically, bacterial expression of enterococcal fibronectin-binding protein A (EfbA) was correlated with adhesive potential of E. faecalis strains. Knockout of fibronectin 1, a binding partner of EfbA, in iPDECs resulted in suppressed E. faecalis adhesion and invasion, suggesting the importance of the EfbA-fibronectin axis in infection of pancreatic ductal epithelial lineage cells. Overall, these results suggest that E. faecalis can colonize pancreatic tissue by infecting iPDECs, at least in part, via the expression of the cell adhesion factor EfbA.

First Detection and Genomic Characterization of Linezolid-Resistant Enterococcus faecalis Clinical Isolates in Bulgaria

Linezolid is an oxazolidinone antibiotic and is considered a last-resort treatment option for serious infections caused by problematic Gram-positive pathogens, including vancomycin-resistant enterococci. The present study aimed to explore the linezolid resistance mechanisms and genomic characteristics of two vancomycin-susceptible Enterococcus faecalis isolates from Bulgaria. The strains designated Efs2503-bg (inpatient from Pleven) and Efs966-bg (outpatient from Varna) were recovered from wounds in 2018 and 2023, respectively. Antimicrobial susceptibility testing, whole-genome sequencing, multilocus sequence typing, and phylogenomic analysis based on 332 linezolid-resistant E. faecalis genomes were performed. Efs2503-bg was high-level resistant to linezolid (MIC > 256 mg/L) and displayed the G2576T mutation affecting three of the four 23S rDNA loci. Efs966-bg (MIC = 8 mg/L) carried a plasmid-located optrA determinant surrounded by fexA and ermA. No mutations in the genes encoding for ribosomal proteins L3, L4, and L22 were detected. The isolates belonged to the sequence types ST6 (Efs2503-bg) and ST1102 (Efs966-bg). Phylogenomic analysis revealed that Efs2503-bg and Efs966-bg are genetically distinct, with a difference of 12,051 single-nucleotide polymorphisms. To our knowledge, this is the first report of linezolid-resistant enterococci in Bulgaria. Although the global incidence of linezolid-resistant enterococci is still low, their emergence is alarming and poses a growing clinical threat to public health.

Electroacupuncture may protect pulmonary dysplasia in offspring with perinatal nicotine exposure by altering maternal gut microbiota and metabolites

Background

Perinatal nicotine exposure (PNE) induces pulmonary dysplasia in offspring and it increases the risk of respiratory diseases both in offspring and across generations. The maternal gut microbiota and its metabolites, such as short-chain fatty acids (SCFAs), can regulate fetal lung development and are susceptible to nicotine exposure. Therefore, modulation of PNE-induced changes in maternal gut microbiota and SCFAs may prevent the occurrence of pulmonary dysplasia in offspring.

Objective

Our previous studies demonstrated that electroacupuncture (EA) ameliorated PNE-induced impairment in offspring lung development. To further our study, we aimed to determine whether the protective effect of EA is associated with the modulation of changes in maternal gut microbiota and SCFAs.

Methods

We observed changes in maternal gut microbiota and serum SCFA levels in both mother and offspring after EA treatment using a PNE rat model. Furthermore, using broad-spectrum antibiotics, we established a pseudo-germ-free PNE rat model to explore whether EA can protect offspring's pulmonary function and lung morphology in the presence of depleted maternal gut microbiota.

Results

Our study revealed that EA increased the community richness (Sobs index) of perinatal nicotine-exposed maternal gut microbiota and the abundance of beneficial bacteria (RF39, Clostridia, Oscillospirales, etc.). This was accompanied by an upregulated serum levels of acetate, butyrate, and total SCFAs in both mother and offspring rats, as well as stimulated expression of SCFA receptors (GPR41 and GPR43) in the lung tissue of offspring rats. However, the beneficial effects of EA on offspring pulmonary function (FVC, PEF, PIF, and Cdyn) and lung morphology (alveolar number and MLI) were lost after maternal gut microbiota depletion.

Conclusion

These findings suggest that EA may exert its therapeutic effects on PNE-induced lung phenotype by altering maternal gut microbiota. The likely mechanism involves the associated improvement in serum SCFA levels in both mother and offspring, as well as the upregulation of SCFA receptors in the lung tissue of offspring.

Effects of antibiotic therapy on the early development of gut microbiota and butyrate-producers in early infants

Background

Antibiotics, as the most commonly prescribed class of drugs in neonatal intensive care units, have an important impact on the developing neonatal gut microbiota. Therefore, comprehending the effects of commonly used antibiotic therapy on the gut microbiota and butyrate-producers in early infants could provide information for therapeutic decision-making in the NICU.

Objectives

To explore the effects of antibiotic therapy on the early development of gut microbiota and butyrate-producers in early infants.

Methods

A total of 72 infants were included in the study. We performed 16S rRNA sequencing on stool swab samples collected from neonatal intensive care unit patients who received amoxicillin-clavulanic acid (AC, n = 10), moxalactam (ML, n = 28) and non-antibiotics (NA, n = 34). We then compared the taxonomic composition between treatment regimens, focusing on differences in butyrate-producers.

Results

Our study showed that there were significant differences in Shannon index (p = 0.033) and Beta diversity (p = 0.014) among the three groups. At the family level, compared with the other two groups, the relative abundance of Clostridiaceae (p < 0.001) and Veillonellaceae (p = 0.004) were significantly higher, while the relative abundance of Enterococcidae (p < 0.001) was significantly lower in the NA group. The relative abundance of Enterobacteriaceae (p = 0.022) in the AC group was greater than that in the other two groups. Additionally, butyrate-producers (p < 0.001), especially Clostridiaceae (p < 0.001), were noticeably more abundant in the NA group. The relative abundance of Clostridiaceae and butyrate-producers were the lowest in the ML group (p < 0.001).

Conclusion

We found that antibiotic therapy had an adverse impact on the initial development of gut microbiota and leaded to a reduction in the abundance of butyrate-producers, particularly Clostridiaceae. Furthermore, moxalactam had a more pronounced effect on the gut microbiota compared to amoxicillin-clavulanic acid.

The prevalence of optrA-carrying Enterococci in the vaginal micro-ecology of pregnant women in late pregnancy

The colonization of Enterococcus in the female vagina leads to neonatal and pediatric enterococcal septicemia. Linezolid (LZD) is a kind of mainstream drug for treating multidrug-resistant Gram-positive infections. OptrA is the main LZD-resistance gene at Enterococci in human isolates. It is essential to explore the prevalence of optrA-carrying Enterococcus in vaginal secretions of late pregnant women and the drug resistance of optrA. From May to June 2023, this study recruited 340 volunteers in late pregnancy (35-40 weeks of pregnancy) to provide non-repetitive vaginal discharge samples. Luria-Bertani broth and florfenicol (10 µg/mL) were used to enrich bacteria. Enterococci was identified through time-of-flight mass spectrometry. Additionally, antimicrobial susceptibility, polymerase chain reaction, and next-generation sequencing assays were applied to this study. Fifty-four optrA-carrying Enterococcus strains were obtained, the proportion of the whole vagina of late pregnant women was 15.88% (54 out of 340), and Enterococcus faecalis account the highest proportion. All optrA-carrying Enterococcus were resistant to at least three drugs. Tetracycline, chloramphenicol, erythromycin, and LZD have higher bacterial resistance rates. Genetic environment analysis revealed that IS1216E, fexA, and erm(A) may synergistically exert multidrug resistance with optrA. It is necessary to strengthen the surveillance of optrA-carrying Enterococcus in pregnant women. This study provides scientific support for controlling hospital infections and managing antibiotic-resistant bacteria, and provides a scientific basis for rational clinical medication.IMPORTANCEThe disruption of cervicovaginal microbiota homeostasis is considered a key factor in causing imbalance in the microenvironment, leading to inflammation, transmission of infections, and illness. Enterococcus is considered a major cause of healthcare-related infections globally. It has resistance to multiple antimicrobial drugs, which pose significant challenges for clinical treatment. Therefore, it is crucial to assess the prevalence of optrA-carrying Enterococcus in vaginal secretions of late pregnant women and the drug resistance of optrA. This study detected 15.88% of optrA-carried Enterococci in 340 pregnant women. Furthermore, we found that optrA-carrying Enterococcus strains are highly resistant to tetracycline, chloramphenicol, erythromycin, and Linezolid. Additionally, genetic environment analysis revealed that IS1216E, fexA, and erm(A) may synergistically exert multidrug resistance with optrA. This study provides scientific support for controlling hospital infections and managing antibiotic-resistant bacteria and provides a scientific basis for rational clinical medication.

Encapsulation of Hydrogen Peroxide in PVA/PVP Hydrogels for Medical Applications

Researchers have been investigating the physical and morphological properties of biodegradable polymer and copolymer films, blending them with other chemicals to solve challenges in medical, industrial, and eco-environmental fields. The present study introduces a novel, straightforward method for preparing biodegradable hydrogels based on polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) for medical applications. The resulting PVA/PVP-based hydrogel uniquely combines the water absorbency, biocompatibility, and biodegradability of the polymer composite. For hygiene products and medical uses, such as wound healing, hydrogen peroxide (HP) was encapsulated in the PVA/PVP hydrogels for controlled release application. Incorporating PVP into PVA significantly enhances the hydrogel water absorbency and improves the mechanical properties. However, to mitigate the disadvantage of high water absorbency which could result in undesired early dissolution, efforts were made to increase the water resistance and the mechanical characteristics of these hydrogels using freeze-thaw (F/T) cycles and chemical crosslinking PVA chains with trisodium trimetaphosphate (STMP). The resulting hydrogels serve as environmentally friendly bio-based polymer blends, broadening their applications in medical and industrial products. The structural and morphological properties of the hydrogel were characterized using Fourier transform infrared spectroscopy (FTIR), environmental scanning electron microscope analysis (E-SEM), and water-swelling tests. The HP controlled release rate was evaluated through kinetic release experiments using the ex vivo skin model. The antibacterial activity of the hydrogel films was examined on four medically relevant bacteria: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa, with an adapted disk diffusion assay. Using this assay, we also evaluated the antibacterial effect of the hydrogel films over the course of days, demonstrating the HP controlled release from these hydrogels. These findings support further in vivo investigation into controlled HP release systems for improved wound-healing outcomes.

From Isolation to Application: Utilising Phage-Antibiotic Synergy in Murine Bacteremia Model to Combat Multidrug-Resistant Enterococcus faecalis

Enterococcus species, natural inhabitants of the human gut, have become major causes of life-threatening bloodstream infections (BSIs) and the third most frequent cause of hospital-acquired bacteremia. The rise of high-level gentamicin resistance (HLGR) in enterococcal isolates complicates treatment and revives bacteriophage therapy. This study isolated and identified forty E. faecalis clinical isolates, with 30% exhibiting HLGR. The HLGR5 isolate, resistant to fosfomycin, vancomycin, and linezolid, was used to isolate the vB_EfaS_SZ1 phage from effluent water. This phage specifically lysed 42% of HLGR isolates. vB_EfaS_SZ1 demonstrated beneficial traits, including thermal stability, acid-base tolerance, a short latent period, and a large burst size. The phage genome comprises a 40,942 bp linear double-stranded DNA with 65 open reading frames (ORFs). The genome closely resembled Enterococcus phages, classifying it within the Efquatrovirus genus. Phage-antibiotic synergy was assessed using checkerboard assays and time-killing analyses, revealing enhanced bacteriolytic activity of ampicillin and fosfomycin, with significant reductions in minimum inhibitory concentration values. In a mouse bacteremia model, phage-antibiotic combinations significantly reduced E. faecalis liver burden compared to monotherapies. Histopathological analysis confirmed therapeutic synergy, showing reduced inflammation and improved hepatocyte regeneration. These findings underscore the potential of phage vB_EfaS_SZ1 as an adjunct to antibiotic therapy for resistant enterococcal bacteremia.

High prevalence and plasmidome diversity of optrA-positive enterococci in a Shenzhen community, China

Background

The emergence of optrA, which can confer resistance to phenicols and oxazolidinones in Enterococcus spp., poses a growing public health threat.

Methods

102 optrA-positive enterococci (OPEs) including various species were isolated from feces of 719 healthy volunteers in a Shenzhen community, China. Antimicrobial susceptibility of these isolates was tested. Whole-genome sequencing and bioinformatics analysis were performed to characterize molecular epidemiology of OPEs.

Results

Compared to optrA-negative enterococci (ONEs), antimicrobial resistance (linezolid, florfenicol, doxycycline, erythromycin and ciprofloxacin) and presence of antimicrobial resistance genes (ARGs) (fexA, cat, tet(M), erm(A), erm(B) and etc) were higher in OPEs. Phylogenetic analysis revealed that high similarly (19-338 SNPs) was observed between the optrA-positive E. faecalis from community and the strains from patients, animals, and environment. In 102 OPEs, the optrA gene was detected on the chromosome (n = 36), on plasmids (n = 62), or both (n = 4). A diverse range of optrA-carrying plasmid types was identified. The rep9-plasmid replicons were widely detected in E. faecalis (44/66), whereas repUS1-plasmid replicons were widely identified in other enterococcal species (7/66). Most of all ARGs harbored by isolates were co-existed on optrA-carrying plasmids, suggesting that the acquisition of optrA-carrying plasmids will pose a greater threat to public health. Notably, the pAD1 (rep9 family) + DOp1-type plasmids should receive more attention for the transfer of optrA given their high prevalence (36.36%), high number of co-located ARGs with optrA (83.87% of total ARGs) and presence in multiple sources. Tn6674, IS1216E, ISEnfa1 and ISEnfa5 are related to the transfer of chromosomal and plasmids-derived optrA, respectively. The bcrABDR gene cluster, fexA, and erm(A) were frequently identified surrounding optrA and may be transferred with optrA via IS1216E or ISEnfa1.

Conclusion

The transfer of optrA gene is related to a variety of mobile elements (including plasmids, insertion sequences, transposons), which will promote the horizontal transfer of optrA. Moreover, many ARGs co-exist with optrA and could co-transfer with optrA. The acquisition of OPEs and optrA-carrying plasmids will pose a greater threat to public health and should be obtained more attention, especially optrA-positive E. faecalis and pAD1 + DOp1-type plasmids.

Metals in the gut: microbial strategies to overcome nutritional immunity in the intestinal tract

Trace metals are indispensable nutritional factors for all living organisms. During host-pathogen interactions, they serve as crucial resources that dictate infection outcomes. Accordingly, the host uses a defense strategy known as nutritional immunity, which relies on coordinated metal chelation to mitigate bacterial advances. In response, pathogens employ complex strategies to secure these resources at sites of infection. In the gastrointestinal (GI) tract, the microbiota must also acquire metals for survival, making metals a central line of competition in this complex ecosystem. In this minireview, we outline how bacteria secure iron, zinc, and manganese from the host with a focus on the GI tract. We also reflect on how host dietary changes impact disease outcomes and discuss therapeutic opportunities to target bacterial metal uptake systems. Ultimately, we find that recent discoveries on the dynamics of transition metals at the host-pathogen-microbiota interface have reshaped our understanding of enteric infections and provided insights into virulence strategies, microbial cooperation, and antibacterial strategies.

In vitro probiotic potential of lactic acid bacteria isolated from the intestines of Muscovy ducks

The current study was conducted to isolate, test and characterize molecularly and physiologically lactic acid bacteria from the intestines of Muscovy ducks to evaluate their probiotic potential for poultry farming. Three hundred lactic acid bacteria from the gastrointestinal tract of Muscovy ducks were isolated. The strains were phenotypically characterized by observing cell morphology, performing Gram staining, catalase production, and testing their ability to grow in MRS broth at different temperatures, pH values, NaCl concentrations, bile concentration, and in compatibility tests between strains. Nine strains were selected based on their resilience. Eight strains were identified using molecular techniques. These strains exhibited significant tolerance to acidic pH, bile salts, and NaCl, essential for probiotic function. All isolates inhibited the growth of Salmonella enterica serotype Typhimurium (DT104) and Enteropathogenic Escherichia coli serotype O86:H34 (EPEC), showcasing their antimicrobial potential. Antibiotic susceptibility testing revealed 100% resistance to clindamycin and erythromycin but high susceptibility to ampicillin and vancomycin. Growth was observed at various temperatures, indicating mesophilic characteristics. Compatibility tests confirmed their suitability for probiotic formulations. Genomic analysis identified the strains primarily as Enterococcus. Conclusively, the study identified eight out of nine selected lactic acid bacteria strains from Muscovy ducks as autochthonous probiotics, showing resilience to treatments and compatibility for consortium formulation. These strains are suitable for in vivo testing for potential poultry farming applications. Further research on their molecular mechanisms and in vivo effects is needed.

Isolation, Genomics-Based and Biochemical Characterization of Bacteriocinogenic Bacteria and Their Bacteriocins, Sourced from the Gastrointestinal Tract of Meat-Producing Pigs

Antimicrobial resistance (AMR) poses a significant challenge to animal production due to the widespread use of antibiotics. Therefore, there is an urgent need for alternative antimicrobial strategies to effectively manage bacterial infections, protect animal health, and reduce reliance on antibiotics. This study evaluated the use of emerging approaches and procedures for the isolation, identification, and characterization of bacteriocin-producing bacteria and their bacteriocins, sourced from the gastrointestinal tract (GIT) of meat-producing pigs. Out of 2056 isolates screened against Gram-positive and Gram-negative indicator strains, 20 of the most active antimicrobial isolates were subjected to whole genome sequencing (WGS) for the prediction of coding DNA sequences (CDS) and the identification of bacteriocin gene clusters (BGC) and their functions. The use of an in vitro cell-free protein synthesis (IV-CFPS) protocol and the design of an IV-CFPS coupled to a split-intein mediated ligation (IV-CFPS/SIML) procedure made possible the evaluation of the production and antimicrobial activity of described and putatively novel bacteriocins. A colony MALDI-TOF MS procedure assisted in the identification of class I, II, and III lanthipeptides. MALDI-TOF MS and a targeted proteomics, combined with a massive peptide analysis (LC-MS/MS) approach, has proven valuable for the identification and biochemical characterization of previously described and novel bacteriocins encoded by the isolated bacteriocin-producing strains.

Comparative analysis of the postadmission and antemortem oropharyngeal and rectal swab microbiota of ICU patients

Shotgun metabarcoding was conducted to examine the microbiota in a total of 48 samples from 12 critically ill patients, analyzing samples from both the oropharynx and rectum. We aimed to compare their postadmission microbiota, characterized as moderately dysbiotic, with the severely dysbiotic antemortem microbiota associated with patients' deaths. We found that, compared with postadmission samples, patient antemortem swab samples presented moderate but not significantly decreased diversity indices. The antemortem oropharyngeal samples presented an increase in biofilm-forming bacteria, including Streptococcus oralis, methicillin-resistant Staphylococcus aureus (MRSA), and Enterococcus faecalis. Although the septic shock rate was 67%, no significant differences were detected in the potential pathogen ratios when the microbiota was analyzed. A notable strain-sharing rate between the oropharynx and intestine was noted. By comparing postadmission and antemortem samples, microbial biomarkers of severe dysbiosis were pinpointed through the analysis of differentially abundant and uniquely emerging species in both oropharyngeal and rectal swabs. Demonstrating strong interconnectivity along the oral-intestinal axis, these biomarkers could serve as indicators of the progression of dysbiosis. Furthermore, the microbial networks of the oropharyngeal microbiota in deceased patients presented the lowest modularity, suggesting a vulnerable community structure. Our data also highlight the critical importance of introducing treatments aimed at enhancing the resilience of the oral cavity microbiome, thereby contributing to better patient outcomes.

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.

Enterococcus faecalis co-cultured with oral cancer cells exhibits higher virulence and promotes cancer cell survival, proliferation, and migration: an in vitro study

Introduction. Enterococcus faecalis is a common pathogen associated with many oral diseases and is often isolated from oral cancer patients. However, limited information is available on its key virulence gene expression in oral cancer cell microenvironment and cancer cell behaviour in co-culture studies.Hypothesis. E. faecalis overexpresses virulence genes when co-cultured with oral cancer cells and possibly alters the tumour microenvironment, promoting oral cancer proliferation and survival.Aim. To investigate altered virulence gene expression in E. faecalis and oral cancer cell behaviour using in vitro co-culture experiments.Methodology. Cal27 cells were co-cultured with E. faecalis and assessed for their cell proliferation, apoptosis, migration and clonogenicity using standard cell culture assays. The levels of reactive oxygen species (ROS) and inflammatory cytokines, along with proliferative, angiogenic and apoptotic biomarker expressions, were also assessed. E. faecalis adherence to cancer cells was demonstrated by the gentamicin protection assay. Real time-PCR was used to analyse the expression of virulence genes.Results. Co-culture of Cal27 cells with E. faecalis showed significantly higher cell proliferation, migration and clonogenicity compared to the control (P<0.01). A significant increase in the levels of ROS and inflammatory cytokines and overexpression of Ki67, vascular endothelial growth factor, extracellular signal-regulated kinase 1/2, phosphoinositide 3 kinase and Akt was observed in the co-culture group. E. faecalis also downregulated p53 and Bax genes while upregulated Bcl-2. The virulence genes GelE, Asa and Ace were overexpressed in E. faecalis co-cultured with Cal27 cells.Conclusion. The results from this study indicate the possible risks of E. faecalis infection in oral cancer. An effective antibiotic strategy against E. faecalis to prevent complications associated with oral diseases, including cancer, is needed.

Bacteriocin distribution patterns in Enterococcus faecium and Enterococcus lactis: bioinformatic analysis using a tailored genomics framework

Multidrug-resistant Enterococcus faecium strains represent a major concern due to their ability to thrive in diverse environments and cause life-threatening infections. While antimicrobial resistance and virulence mechanisms have been extensively studied, the contribution of bacteriocins to E. faecium's adaptability remains poorly explored. E. faecium, within the Bacillota phylum, is a prominent bacteriocin producer. Here, we developed a tailored database of 76 Bacillota bacteriocins (217 sequences, including 40 novel bacteriocins) and applied it to uncover bacteriocin distribution patterns in 997 quality-filtered E. faecium and Enterococcus lactis (former E. faecium clade B) genomes. Curated using computational pipelines and literature mining, our database demonstrates superior precision versus leading public tools in identifying diverse bacteriocins. Distinct bacteriocin profiles emerged between E. faecium and E. lactis, highlighting species-specific adaptations. E. faecium strains from hospitalized patients were significantly enriched in bacteriocins as enterocin A and bacteriocins 43 (or T8), AS5, and AS11. These bacteriocin genes were strongly associated with antibiotic resistance, particularly vancomycin and ampicillin, and Inc18 rep2_pRE25-derivative plasmids, classically associated with vancomycin resistance transposons. Such bacteriocin arsenal likely enhances the adaptability and competitive fitness of E. faecium in the nosocomial environment. By combining a novel tailored database, whole-genome sequencing, and epidemiological data, our work elucidates meaningful connections between bacteriocin determinants, antimicrobial resistance, mobile genetic elements, and ecological origins in E. faecium and provides a framework for elucidating bacteriocin landscapes in other organisms. Characterizing species- and strain-level differences in bacteriocin profiles may reveal determinants of ecological adaptation, and translating these discoveries could further inform strategies to exploit bacteriocins against high-risk clones.

IMPORTANCE

This work significantly expands the knowledge on the understudied bacteriocin diversity in opportunistic enterococci, revealing their contribution in the adaptation to different environments. It underscores the importance of placing increased emphasis on genetic platforms carrying bacteriocins as well as on cryptic plasmids that often exclusively harbor bacteriocins since bacteriocin production can significantly contribute to plasmid maintenance, potentially facilitating their stable transmission across generations. Further characterization of strain-level bacteriocin landscapes could inform strategies to combat high-risk clones. Overall, these insights provide a framework for unraveling the therapeutic and biotechnological potential of bacteriocins.

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

BACKGROUND

The 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.

METHODS

In 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.

RESULTS

The 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).

CONCLUSION

Polidocanol appears to be a promising option for treating of E. faecalis infections by targeting the fsr QS system and exhibiting anti-biofilm activity.