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

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

Enterococcus faecalis Infective Endocarditis Associated With Colorectal Cancer.

Enterococcus faecalis (E. faecalis) is considered the third most common source of infective endocarditis. Some of the published reports linked its origin to colorectal cancer. We report a 70-year-old male patient diagnosed with E. faecalis infective endocarditis complicated by myocardial infarction. The patient also experienced symptoms of melena and anemia, prompting a colonoscopy. A colon mass was found and a biopsy revealed adenocarcinoma. The patient underwent a left hemicolectomy. In addition to that, he was treated for his cardiac issues. Many studies suggest screening for colonoscopy in patients with E. faecalis infective endocarditis to investigate its origin and potential association with colorectal cancer.

An Ex-vivo Comparative Study to Evaluate the Efficacy of Three Root Canal Irrigation Systems in Reduction of Enterococcus Faecalis.

Aim: The purpose of this ex-vivo study is to evaluate the efficacy of three irrigation techniques in the reduction of E. faecalis in root canal. Materials and Methods: Eighty healthy maxillary anteriors were employed in this investigation. The bacteria E. faecalis was left on teeth for 7 days while they were kept. Once teeth were contaminated, they were randomly divided into three groups of 20 for experimentation and a control group of 20 for comparison. NaviTip FX was used to irrigate Group I, the Max-I-probe was used to water Group II, and the Endovac system was used to water Group III. The number of colony forming units (CFUs) was determined by growing bacteria from root canal samples for 2 days in Brain heart infusion agar after chemo-mechanical operations. Results: There was a substantial decrease in bacterial numbers across all experimental groups compared to group IV (control). Group III (Endovac) had the fewest bacterial colonies among the test groups. There were no discernible changes between Group I (the Navitip FX) and Group II (the Max I probe). Conclusion: Endovac was the most effective of the three irrigation methods for reducing CFUs. This study's findings lend credence to the idea that the apical negative pressure approach has more potential than the conventional irrigation delivery system for achieving an enhanced antibacterial impact.

Comparative analysis of proteomic adaptations in Enterococcus faecalis and Enterococcus faecium after long term bile acid exposure.

BACKGROUND: All gastrointestinal pathogens, including Enterococcus faecalis and Enterococcus faecium, undergo adaptation processes during colonization and infection. In this study, we investigated by data-independent acquisition mass spectrometry (DIA-MS) two crucial adaptations of these two Enterococcus species at the proteome level. Firstly, we examined the adjustments to cope with bile acid concentrations at 0.05% that the pathogens encounter during a potential gallbladder infection. Therefore, we chose the primary bile acids cholic acid (CA) and chenodeoxycholic acid (CDCA) as well as the secondary bile acid deoxycholic acid (DCA), as these are the most prominent bile acids. Secondly, we investigated the adaptations from an aerobic to a microaerophilic environment, as encountered after oral-fecal infection, in the absence and presence of deoxycholic acid (DCA). RESULTS: Our findings showed similarities, but also species-specific variations in the response to the different bile acids. Both Enterococcus species showed an IC50 in the range of 0.01- 0.023% for DCA and CDCA in growth experiments and both species were resistant towards 0.05% CA. DCA and CDCA had a strong effect on down-expression of proteins involved in translation, transcription and replication in E. faecalis (424 down-expressed proteins with DCA, 376 down-expressed proteins with CDCA) and in E. faecium (362 down-expressed proteins with DCA, 391 down-expressed proteins with CDCA). Proteins commonly significantly altered in their expression in all bile acid treated samples were identified for both species and represent a "general bile acid response". Among these, various subunits of a V-type ATPase, different ABC-transporters, multi-drug transporters and proteins related to cell wall biogenesis were up-expressed in both species and thus seem to play an essential role in bile acid resistance. Most of the differentially expressed proteins were also identified when E. faecalis was incubated with low levels of DCA at microaerophilic conditions instead of aerobic conditions, indicating that adaptations to bile acids and to a microaerophilic atmosphere can occur simultaneously. CONCLUSIONS: Overall, these findings provide a detailed insight into the proteomic stress response of two Enterococcus species and help to understand the resistance potential and the stress-coping mechanisms of these important gastrointestinal bacteria.

Membrane Lipids Augment Cell Envelope Stress Signaling via the MadRS System to Defend Against Antimicrobial Peptides and Antibiotics in Enterococcus faecalis.

Enterococci have evolved resistance mechanisms to protect their cell envelopes against bacteriocins and host cationic antimicrobial peptides (CAMPs) produced in the gastrointestinal environment. Activation of the membrane stress response has also been tied to resistance to the lipopeptide antibiotic daptomycin. However, the actual effectors mediating resistance have not been elucidated. Here, we show that the MadRS (formerly YxdJK) membrane antimicrobial peptide defense system controls a network of genes, including a previously uncharacterized three gene operon (madEFG) that protects the E. faecalis cell envelope from antimicrobial peptides. Constitutive activation of the system confers protection against CAMPs and daptomycin in the absence of a functional LiaFSR system and leads to persistence of cardiac microlesions in vivo. Moreover, changes in the lipid cell membrane environment alter CAMP susceptibility and expression of the MadRS system. Thus, we provide a framework supporting a multilayered envelope defense mechanism for resistance and survival coupled to virulence.

Analysis of the Cadmium Removal Mechanism of Human Gut Bacteria Enterococcus faecalis Strain ATCC19433 from a Genomic Perspective.

Cadmium (Cd) is one of the most well-known toxic metals capable of entering the human body via the food chain, leading to serious health problems. Human gut microbes play a pivotal role in controlling Cd bioavailability and toxicity within the human gastrointestinal tract, primarily due to their capacity for Cd adsorption and metabolism. In this work, a Cd-resistant bacterial strain, Enterococcus faecalis strain ATCC19433 was isolated from human gut microbiota. Cd binding assays and comprehensive characterization analyses were performed, revealing the ability of strain ATCC19433 to remove Cd from the solution. Cd adsorption primarily occurred on the bacterial cell walls, which was ascribed to the exciting of functional groups on the bacterial surfaces, containing alkyl, amide II, and phosphate groups; meanwhile, Cd could enter cells, probably through transport channels or via diffusion. These results indicated that Cd removal by the strain was predominantly dependent on biosorption and bioaccumulation. Whole-genome sequencing analyses further suggested the probable mechanisms of biosorption and bioaccumulation, including Cd transport by transporter proteins, active efflux of Cd by cadmium efflux pumps, and mitigating oxidative stress-induced cell damage by DNA repair proteases. This study evaluated the Cd removal capability and mechanism of Enterococcus faecalis strain ATCC19433 while annotating the genetic functions related to Cd removal, which may facilitate the development of potential human gut strains for the removal of Cd.

Sortase-encoding genes, srtA and srtC, mediate Enterococcus faecalis OG1RF persistence in the Helicoverpa zea gastrointestinal tract.

Enterococcus faecalis is a commensal and opportunistic pathogen in the gastrointestinal (GI) tract of mammals and insects. To investigate mechanisms of bacterial persistence in the gastrointestinal tract (GIT), we developed a non-destructive sampling model using Helicoverpa zea, a destructive agricultural pest, as host to study the role of bacterial sortase enzymes in mitigating persistence in the gastrointestinal tract. E. faecalis OG1RF ΔsrtA and E. faecalis OG1RF ΔsrtC, isogenic E. faecalis OG1RF sortase mutants grew similarly under planktonic growth conditions relative to a streptomycin-resistant E. faecalis OG1RFS WT in vitro but displayed impaired biofilm formation under, both, physiological and alkaline conditions. In the H. zea GI model, both mutants displayed impaired persistence relative to the WT. This represents one of the initial reports in which a non-destructive insect model has been used to characterize mechanisms of bacterial persistence in the Lepidopteran midgut and, furthermore, sheds light on new molecular mechanisms employed by diverse microorganisms to associate with invertebrate hosts.

Enterococcus faecalis provides protection during scavenging in carrion crow ( Corvus corone).

The gut microbiota significantly influences host physiology and provides essential ecosystem services. While diet can affect the composition of the gut microbiota, the gut microbiota can also help the host adapt to specific dietary habits. The carrion crow ( Corvus corone), an urban facultative scavenger bird, hosts an abundance of pathogens due to its scavenging behavior. Despite this, carrion crows infrequently exhibit illness, a phenomenon related to their unique physiological adaptability. At present, however, the role of the gut microbiota remains incompletely understood. In this study, we performed a comparative analysis using 16S rRNA amplicon sequencing technology to assess colonic content in carrion crows and 16 other bird species with different diets in Beijing, China. Our findings revealed that the dominant gut microbiota in carrion crows was primarily composed of Proteobacteria (75.51%) and Firmicutes (22.37%). Significant differences were observed in the relative abundance of Enterococcus faecalis among groups, highlighting its potential as a biomarker of facultative scavenging behavior in carrion crows. Subsequently, E. faecalis isolated from carrion crows was transplanted into model mice to explore the protective effects of this bacterial community against Salmonella enterica infection. Results showed that E. faecalis down-regulated the expression of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α), interferon gamma (IFN-γ), and interleukin 6 (IL-6), prevented S. enterica colonization, and regulated the composition of gut microbiota in mice, thereby modulating the host's immune regulatory capacity. Therefore, E. faecalis exerts immunoregulatory and anti-pathogenic functions in carrion crows engaged in scavenging behavior, offering a representative case of how the gut microbiota contributes to the protection of hosts with specialized diets.

Evaluation of minimum inhibitory concentration and minimum bactericidal concentration of royal jelly against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans.

Objective: The objective of this study was to ascertain the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of royal jelly (RJ) against three microorganisms frequently linked with endodontic infections: Staphylococcus aureus, Enterococcus faecalis, and Candida albicans. Materials and Methods: Freshly harvested RJ was prepared at different concentrations (20%, 10%, 5%, 2.5%, and 1.25%) in distilled water. The microbial cultures of the target organisms were prepared. MIC was determined using a broth dilution technique, monitoring microbial growth. MBC was determined by inoculating agar plates with samples from tubes showing no apparent growth and evaluating the presence of bacterial or fungal growth following the incubation period. Results: For S. aureus, the MIC and MBC were 5 mg/ml of RJ. For E. faecalis, the MIC and MBC were 10 mg/ml of RJ. For C. albicans, both MIC and MBC were 10 mg/ml of RJ. The findings demonstrated RJ's potential to inhibit and eliminate these pathogenic microorganisms, making it a potential candidate for endodontic infection control. Conclusion: The antimicrobial properties of RJ against S. aureus, E. faecalis, and C. albicans present a promising avenue for enhancing infection control in endodontics. Additional investigations are needed to refine its use in clinical settings, especially in cases with mixed microbial infections.

Prevalence and virulence factors of haemolytic Enterococcus faecalis isolated from root filled teeth associated with periradicular lesions: A laboratory investigation in Thailand.

AIM: Previous endodontic research has provided limited understanding of the prevalence and roles of haemolytic and non-haemolytic Enterococcus faecalis strains in root filled teeth. This study aimed to determine the prevalence of these strains in root filled teeth with periradicular lesions and investigate their associated virulence factors. METHODOLOGY: A total of 36 root canal samples were collected from 36 subjects. The prevalence of E. faecalis was determined using culture and PCR methods. Antibiotic susceptibility of haemolytic and non-haemolytic E. faecalis strains was assessed using the broth dilution assay. The cytokine stimulation in periodontal ligament (PDL) cells and neutrophil migration were evaluated using real-time PCR and migration assay, respectively. Cell invasion ability of the strains was assessed using a cell culture model. Additionally, the virulence gene expression of the haemolytic and non-haemolytic strains was investigated using real-time PCR. The Mann-Whitney U and Spearman's ρ tests were used to examine the significant difference between the two strains and to analyse the correlation between phenotype and gene expression, respectively. RESULTS: Enterococcus faecalis was detected in 33.3% and 88.9% of samples by culture and real-time PCR, respectively. Haemolytic strains were found in 36.4% of subjects. Non-haemolytic strains exhibited susceptibility to erythromycin and varying susceptibility to tetracycline, while all haemolytic strains were resistant to both antibiotics. Haemolytic strains significantly upregulated the expression of IL-8, OPG and RANKL in PDL cells (p < .05). Notably, the fold increases in these genes were higher: IL-8 (556.1 ± 82.9 vs. 249.6 ± 81.8), OPG (2.2 ± 0.5 vs. 1.3 ± 0.2) and RANKL (1.8 ± 0.3 vs. 1.2 ± 0.1). Furthermore, haemolytic strains had a greater effect on neutrophil migration (68.7 ± 15.2% vs. 46.9 ± 11.4%) and demonstrated a higher level of internalization into oral keratinocyte cells (68.6 ± 0.4% vs. 33.8 ± 0.5%) (p < .05). They also showed enhanced expression of virulence genes associated with haemolysin, surface proteins, collagen-binding and aggregation substances. Gelatinase activity was only detectable in non-haemolytic strains. CONCLUSIONS: This study revealed that haemolytic strains E. faecalis possessed enhanced abilities in host invasion and a higher abundance of virulence factors, suggesting their potential contribution to more severe disease manifestations.

Current Knowledge of Enterococcal Endocarditis: A Disease Lurking in Plain Sight of Health Providers.

Enterococcus faecalis is a bacterial pathogen that can cause opportunistic infections. Studies indicate that initial biofilm formation plays a crucial regulatory role in these infections, as well as in colonising and maintaining the gastrointestinal tract as a commensal member of the microbiome of most land animals. It has long been thought that vegetation of endocarditis resulting from bacterial attachment to the endocardial endothelium requires some pre-existing tissue damage, and in animal models of experimental endocarditis, mechanical valve damage is typically induced by cardiac catheterisation preceding infection. This section reviews historical and contemporary animal model studies that demonstrate the ability of E. faecalis to colonise the undamaged endovascular endothelial surface directly and produce robust microcolony biofilms encapsulated within a bacterially derived extracellular matrix. This report reviews both previous and current animal model studies demonstrating the resilient capacity of E. faecalis to colonise the undamaged endovascular endothelial surface directly and produce robust microcolony biofilms encapsulated in a bacterially derived extracellular matrix. The article also considers the morphological similarities when these biofilms develop on different host sites, such as when E. faecalis colonises the gastrointestinal epithelium as a commensal member of the common vertebrate microbiome, lurking in plain sight and transmitting systemic infection. These phenotypes may enable the organism to survive as an unrecognised infection in asymptomatic subjects, providing an infectious resource for subsequent clinical process of endocarditis.

Fully Characterized Effective Bacteriophages Specific against Antibiotic-Resistant Enterococcus faecalis, the Causative Agent of Dental Abscess.

Background and Objectives: Enterococcus faecalis (E. faecalis) is a primary pathogen responsible for dental abscesses, which cause inflammation and pain when trapped between the crown and soft tissues of an erupted tooth. Therefore, this study aims to use specific phages as an alternative method instead of classical treatments based on antibiotics to destroy multidrug-resistant E. faecalis bacteria for treating dental issues. Materials and Methods: In the current study, twenty-five bacterial isolates were obtained from infected dental specimens; only five had the ability to grow on bile esculin agar, and among these five, only two were described to be extensive multidrug-resistant isolates. Results: Two bacterial isolates, Enterococcus faecalis A.R.A.01 [ON797462.1] and Enterococcus faecalis A.R.A.02, were identified biochemically and through 16S rDNA, which were used as hosts for isolating specific phages. Two isolated phages were characterized through TEM imaging, which indicated that E. faecalis_phage-01 had a long and flexible tail, belonging to the family Siphoviridae, while E. faecalis_phage-02 had a contractile tail, belonging to the family Myoviridae. Genetically, two phages were identified through the PCR amplification and sequencing of the RNA ligase of Enterococcus phage vB_EfaS_HEf13, through which our phages shared 97.2% similarity with Enterococcus phage vB-EfaS-HEf13 based on BLAST analysis. Furthermore, through in silico analysis and annotations of the two phages' genomes, it was determined that a total of 69 open reading frames (ORFs) were found to be involved in various functions related to integration excision, replication recombination, repair, stability, and defense. In phage optimization, the two isolated phages exhibited a high specific host range with Enterococcus faecalis among six different bacterial hosts, where E. faecalis_phage-01 had a latent period of 30 min with 115.76 PFU/mL, while E. faecalis_phage-02 had a latent period of 25 min with 80.6 PFU/mL. They were also characterized with stability at wide ranges of pH (4-11) and temperature (10-60 °C), with a low cytotoxic effect on the oral epithelial cell line at different concentrations (1000-31.25 PFU/mL). Conclusions: The findings highlight the promise of phage therapy in dental medicine, offering a novel approach to combating antibiotic resistance and enhancing patient outcomes. Further research and clinical trials will be essential to fully understand the therapeutic potential and safety profile of these bacteriophages in human populations.

In vitro antibiofilm effect of different irradiation doses in infected root canal model.

BACKGROUND: Eradication of endodontic biofilms from the infected root canal system is still the main concern in endodontics. In this study, the role of the power density parameter in the efficacy of antimicrobial photodynamic therapy (PDT) with toluidine blue O (TBO) and phycocyanin (PC) activated by a 635 nm diode laser (DL) against Enterococcus faecalis biofilm in the root canal model was investigated. MATERIALS AND METHODS: The E. faecalis biofilm in the root canal was treated with TBO and PC with different power densities (636, 954, 1273, and 1592 W/cm2). The untreated biofilm represented the control group. After the treatments, the biofilms were analyzed based on the number of colonies per milliliter. RESULTS: TBO and PC activated with 635 nm DL with a power density of 1592 W/cm2 were more efficient in removing E. faecalis biofilms within the root canals than those with a power density of 636 W/cm2 (p = 0.00). CONCLUSION: The light power density optimized the bacterial reduction of E. faecalis biofilms in the root canal spaces. These results provide information on the decisive parameters for performing PDT on intracanal biofilms.

Comparative evaluation of antimicrobial efficacy of triple antibiotic paste and amoxicillin clavulanate paste as an intracanal medicament against Enterococcus faecalis: An in vitro study.

Background: Triple antibiotic paste (TAP) is the commonly used intracanal medicament against Enterococcus faecalis. Amoxicillin clavulanate paste (ACP) is recommended as a "fall-back" antibiotic when traditional dental antibiotics fail. Literature comparing the antimicrobial efficacy of TAP and ACP in eradicating E. faecalis from the root canal system is sparse; hence, this in vitro study was conducted to evaluate and compare the antimicrobial efficacy of TAP and ACP as an intracanal medicament for endodontic treatment of single-rooted permanent teeth against E. faecalis. Materials and Methods: This in vitro, experimental study evaluated 60 root samples obtained from extracted single-rooted human permanent teeth. The canal diameter was enlarged and subsequently infected with E. faecalis for 21 days. Four groups of the contaminated samples were treated with TAP, ACP, calcium hydroxide (positive control), and saline (negative control), respectively. Dentinal shavings were collected at the end of the 1st, 7th, and 10th day and inoculated in agar plates. The number of colony-forming units was determined, and the data were statistically analyzed using the Kolmogorov-Smirnov and Shapiro-Wilks test. P <0.05 was considered statistically significant. Results: The mean number of E. faecalis colony counts across all 3 test days demonstrated that TAP exhibited the highest inhibition of bacterial growth, followed by ACP which is not statistically significant (P = 1.00). Conclusion: Considering the limitations of this in vitro study, the findings suggest that ACP could be an effective alternative intracanal medicament to TAP for endodontic therapy.

Characteristics of Enterococcus species bloodstream infections among adults with and without onco-hematological malignancies: Experiences from the national center of Hungary.

Introduction: Over the past decade, enterococcal bloodstream infection (BSI) shows increasing incidence globally among the elderly and in patients with comorbidities. In this study, we aimed to assess microbiological and clinical characteristics and long-term outcomes of BSIs caused by Enterococcus spp. in adult patients with and without active onco-hematological malignancies hospitalized at a national referral institute. Methods: A prospective analysis of consecutive enterococcal BSI cases was conducted in the National Institute of Hematology and Infectious Diseases (Budapest, Hungary) between December 2019 and April 2022. We compared characteristics and outcomes at 30-days and 1 year after diagnosis among patients with and without onco-hematological malignancies. Results: In total, 141 patients were included (median age 68 ± 21 years, female sex 36.9%), 37% (52/141) had active onco-hematological malignancies. The distribution of species was as follows: 50.4% Enterococcus faecalis, 46.1% Enterococcus faecium, 1.4% Enterococcus avium and Enterococcus gallinarum, and 0.7% Enterococcus raffinosus. No statistically significant differences in all-cause mortality rates were observed between patient subgroups at 30 days (32.7 vs. 28.1%; P = 0.57) and 1 year (75.0 vs. 60.7%; P = 0.09). Conclusion: Enterococcal bloodstream infections yielded a relevant burden of morbidity, but with no statistical difference in long-term outcomes of adult patients with and without active onco-hematological malignancies.

Repurposing fusidic acid as an antimicrobial against enterococci with a low probability of resistance development.

Drug repurposing constitutes a strategy to combat antimicrobial resistance, by using agents with known safety, pharmacokinetics, and pharmacodynamics. Previous studies have implemented new fusidic acid (FA) front-loading-dose regimens, allowing higher serum levels than those achievable with ordinary doses. As susceptibility breakpoints are affected by serum level, we evaluated the repurposing of FA as an antimicrobial product against enterococci. FA minimum inhibitory concentrations (MICs) against standard enterococci strains; Enterococcus faecalis ATCC 29212 and Enterococcus faecium ATCC 27270 were 2 and 4 µg/mL, respectively. The MIC against 98 enterococcal clinical isolates was ≤ 8 µg/mL; all would be susceptible if categorized according to recalculated breakpoints (≥ 16 µg/mL), based on the serum level achieved using the front-loading regimen. FA administration in vivo, using the BALB/c mouse infection model, significantly reduced bacterial burden by two to three log10 units in the liver and spleen of mice infected with vancomycin-susceptible and -resistant strains. Exposure of the standard enterococcal strains to increasing, but not fixed, FA concentrations resulted in resistant strains (MIC = 128 µg/mL), with thicker cell walls and slower growth rates. Only one mutation (M651I) was detected in the fusA gene of the resistant strain derived from serial passage of E. faecium ATCC 27270, which was retained in the revertant strain after passage in the FA-free medium. In conclusion, FA can be repurposed as an antimicrobial drug against enterococci with a low probability of mutational resistance development, and can be employed for treatment of infections attributable to vancomycin-resistant enterococci.

An essential protease, FtsH, influences daptomycin resistance acquisition in Enterococcus faecalis.

Daptomycin is a last-line antibiotic commonly used to treat vancomycin-resistant Enterococci, but resistance evolves rapidly and further restricts already limited treatment options. While genetic determinants associated with clinical daptomycin resistance (DAPR) have been described, information on factors affecting the speed of DAPR acquisition is limited. The multiple peptide resistance factor (MprF), a phosphatidylglycerol-modifying enzyme involved in cationic antimicrobial resistance, is linked to DAPR in pathogens such as methicillin-resistant Staphylococcus aureus. Since Enterococcus faecalis encodes two paralogs of mprF and clinical DAPR mutations do not map to mprF, we hypothesized that functional redundancy between the paralogs prevents mprF-mediated resistance and masks other evolutionary pathways to DAPR. Here, we performed in vitro evolution to DAPR in mprF mutant background. We discovered that the absence of mprF results in slowed DAPR evolution and is associated with inactivating mutations in ftsH, resulting in the depletion of the chaperone repressor HrcA. We also report that ftsH is essential in the parental, but not in the ΔmprF, strain where FtsH depletion results in growth impairment in the parental strain, a phenotype associated with reduced extracellular acidification and reduced ability for metabolic reduction. This presents FtsH and HrcA as enticing targets for developing anti-resistance strategies.

Lipopeptide biosurfactant as a potential root canal irrigation agent: Antimicrobial and anti-biofilm evaluation.

OBJECTIVES: Lipopeptide Biosurfactant (LB) is a bacteria derived compound able to reduce surface tension between water and hydrophobic substances and exhibit antimicrobial and anti-biofilm properties. This study aimed to investigate the antimicrobial and anti-biofilm effect of a Lipopeptide Biosurfactant (LB) on Enterococcus faecalis, and its potential use in root canal treatment, either as a standalone irrigation solution or in conjunction with sodium hypochlorite (NaOCl). METHODS: LB was extracted from Bacillus clausii isolate and the dry extract was diluted in deionized water. The antimicrobial effect of LB against planktonic E. faecalis was evaluated by determining the Minimal Inhibitory Concentration (MIC50). The anti-biofilm effect was evaluated by Minimal Biofilm Inhibitory Concentration (MBIC50) and Minimal Biofilm Eradication Concentration (MBEC50) assays on biofilm grown on dentin specimen surface. To evaluate the effectiveness of LB as a single irrigation solution and as a pre-irrigation prior to NaOCl, live and dead bacterial cells were quantified using Confocal Laser Scanning Microscopy (CLSM), and cell biomass was assessed. RESULTS: LB exhibited an MIC50 and MBIC50 of 100 ppm, with an MBEC50 of 1000 ppm, resulting in 52.94 % biofilm inhibition and 60.95 % biofilm eradication on dentin specimens. The effectiveness was concentration-dependent, at 500 ppm, LB demonstrated comparable antimicrobial efficacy to 2.5 % NaOCl. Pre-irrigation with LB resulted in lower biofilm biomass compared to NaOCl alone. CONCLUSION: Pre-irrigation with LB enhanced the antimicrobial effect when followed by NaOCl irrigation. Consequently, LB shows promise as both a standalone root canal irrigation solution and as an adjunct to NaOCl in root canal treatment. CLINICAL SIGNIFICANCE: The study highlights the potential of Lipopeptide Biosurfactant (LB) as an environmentally friendly irrigation solution for root canal treatment, demonstrating potent antimicrobial and anti-biofilm properties against Enterococcus faecalis. LB exhibits concentration-dependent efficacy comparable to 2.5 % NaOCl and can be used as a standalone irrigation solution or in conjunction with NaOCl.

Study on Biofilm Formation Among Enterococcus Isolates and Association With Their Antibiotic Resistance Patterns.

Background Enterococci are a part of the normal intestinal flora of humans. They have emerged as one of the leading causes of nosocomial infection. The evolved antibiotic resistance mechanisms coupled with the virulence properties of enterococci have made it a successful pathogen. Aim This study aimed to determine the ability of biofilm formation among the clinical enterococci isolates and the antimicrobial resistance pattern of the strains. Materials and methods Clinical samples of patients who attended Saveetha Medical College and Hospital, Chennai, India, over six months. Identification and characterization of Enterococcus species were done using various biochemical tests. Antibiotic susceptibility patterns for each isolate were performed using the Kirby- Bauer disc diffusion method. Results The formation of biofilm formation was detected using the microtiter plate method. In total, 90 Enterococcus species were isolated; Enterococcus faecalis were 63 (70%), Enterococcus faecium were 25 (28%) and Enterococcus gallinarum were 2 (2%)independently. E. faecalis displayed advanced resistance rates compared to other Enterococcus species. Resistance against penicillin was found in 42 strains (47%) and resistance to ampicillin was observed in 39 strains (43%). This was followed by resistance to high-level gentamicin in 35 strains (39%) and resistance to ciprofloxacin in 32 strains (36%). Resistance to vancomycin and linezolid also were noted in some strains. Conclusion Our results indicate that E. faecalis exhibits an increasing rate of antimicrobial resistance but lower biofilm conformation. The unique traits of E. faecalis raise concerns for the associated infections, especially hospital-acquired infections.

Genome-wide analysis of acid tolerance genes of Enterococcus faecalis with RNA-seq and Tn-seq.

Enterococcus faecalis, a formidable nosocomial and community-acquired opportunistic pathogen, can persist a wide range of extreme environments, including low pH and nutrient deficiency. Clarifying the survival mechanism of E. faecalis in low-pH conditions is the key to combating the infectious diseases caused by E. faecalis. In this study, we combined transcriptome profiling (RNA-seq) and transposon insertion sequencing (TIS) to comprehensively understand the genes that confer these features on E. faecalis. The metadata showed that genes whose products are involved in cation transportation and amino acid biosynthesis were predominantly differentially expressed under acid conditions. The products of genes such as opp1C and copY reduced the hydrion concentration in the cell, whereas those of gldA2, gnd2, ubiD, and ubiD2 mainly participated in amino metabolism, increasing matters to neutralize excess acid. These, together with the folE and hexB genes, which are involved in mismatch repair, form a network of E. faecalis genes necessary for its survival under acid conditions.

IMPORTANCE: As a serious nosocomial pathogen, Enterococcus faecalis was considered responsible for large numbers of infections. Its ability to survive under stress conditions, such as acid condition and nutrient deficiency was indispensable for its growth and infection. Therefore, understanding how E. faecalis survives acid stress is necessary for the prevention and treatment of related diseases. RNA-seq and TIS provide us a way to analyze the changes in gene expression under such conditions.