Antibacterial Property and Mechanisms of Au@Ag Core-Shell Nanoparticles with Near-Infrared Absorption Against E. faecalis Infection of Dentin.

Background: Enterococcus faecalis (E. faecalis) is one of the main pathogens responsible for refractory root canal infections in the teeth and shows resistance against various antibacterial managements. Effective control of E. faecalis infection is a prerequisite for successful treatment of refractory apical periodontitis. This study aimed to analyze the antibacterial activity and mechanisms of Au@Ag nanoparticles (NPs) combined with photothermal therapy (PTT) against the original and Ag+-resistant E. faecalis. Methods: Au@AgNPs with optimal shell thicknesses were synthesized and characterized. The antibacterial activity of Au@AgNPs with PTT against the original or Ag+-resistant E. faecalis was evaluated, and the antibiofilm activity was tested on E. faecalis biofilm on the dentin of teeth. The potential antibacterial mechanisms of Au@AgNPs combined with PTT against E. faecalis have also been studied. Moreover, its influence on dentin microhardness and cytotoxicity was assessed. Results: This study revealed that Au@AgNPs combined with PTT showed enhanced antibacterial and antibiofilm effects, no negative effects on dentin microhardness, and low cytotoxicity toward human periodontal ligament cells (hPDLCs). Moreover, Au@AgNPs combined with PTT effectively inhibited the growth of Ag+-resistant E. faecalis. Its antibacterial effects may be exerted through the release of silver ions (Ag+), destruction of the cell membrane, production of reactive oxygen species (ROS) and inhibition of adenosine triphosphate (ATP) production. Hyperthermia generated by Au@AgNPs with PTT reduced membrane fluidity and enhanced Ag+ sensitivity by downregulating fabF expression. The upregulated expression of heat shock genes demonstrated that the Ag+ released from Au@AgNPs compromised the heat adaptation of E. faecalis. Conclusion: PTT significantly enhanced Ag+ sensitivity of the original and Ag+-resistant E. faecalis. Au@AgNPs combined with PTT may have the potential to be developed as a new antibacterial agent to control E. faecalis infections in teeth.

A Rare Case of Enterococcus faecalis Keratitis in a Neurotrophic Cornea Successfully Treated With Topical Antibiotics and Amniotic Membrane.

A patient in his 60s presented with severe keratitis in his right eye. He had a background of diabetes, high body mass index, arthritis and limited mobility, and high alcohol intake. Examination showed lower lid tarsal ectropion, floppy eyelid syndrome, advanced meibomian gland dysfunction, moderate neurotrophia, and large inferior keratitis with hypopyon. Corneal scrapes revealed Enterococcus faecalis, sensitive to vancomycin and ciprofloxacin only. Due to poor compliance with vancomycin, he was started on topical ciprofloxacin resulting in partial improvement but a persistent epithelial defect. Inserting a dry patch of amniotic membrane on the cornea accelerated epithelialization, and 11 weeks from presentation, complete corneal healing was noted. In the presence of multiple systemic and ocular risk factors like diabetes, high body mass index, high alcohol intake, tarsal ectropion, floppy eyelid syndrome, neurotrophic cornea, blepharitis, and ocular surface inflammation, atypical keratitis, like this rare infection, should be suspected. The use of dry amniotic membrane has a role in epithelial healing in patients with neurotrophia.

Biological Traits and Comprehensive Genomic Analysis of Novel Enterococcus faecalis Bacteriophage EFP6.

Enterococcus faecalis is a prevalent opportunistic pathogen associated with chicken embryonic and neonatal chick mortality, posing a significant challenge in poultry farming. In the current study, E. faecalis strain EF6, isolated from a recent hatchery outbreak, served as the host bacterium for the isolation of a novel phage EFP6, capable of lysing E. faecalis. Transmission electron microscopy revealed a hexagonal head and a short tail, classifying EFP6 as a member of the Autographiviridae family. EFP6 showed sensitivity to ultraviolet radiation and resistance to chloroform. The lytic cycle duration of EFP6 was determined to be 50 min, highlighting its efficacy in host eradication. With an optimal multiplicity of infection of 0.001, EFP6 exhibited a narrow lysis spectrum and strong specificity towards host strains. Additionally, EFP6 demonstrated optimal growth conditions at 40 °C and pH 8.0. Whole genome sequencing unveiled a genome length of 18,147 bp, characterized by a GC concentration of 33.21% and comprising 25 open reading frames. Comparative genomic assessment underscored its collinearity with related phages, notably devoid of lysogenic genes, thus ensuring genetic stability. This in-depth characterization forms the basis for understanding the biological attributes of EFP6 and its potential utilization in phage therapy, offering promising prospects for mitigating E. faecalis-associated poultry infections.

Novel antimicrobial applications of copper oxide nanoparticles after combination with tissue conditioner used in complete prostheses.

BACKGROUND: Tissue conditioners are used for treating and improving the tissues supporting complete dentures. On the other hand, recent advances in nanotechnology have revolutionized various fields of science, including dentistry. The present study aimed to investigate novel antimicrobial applications of copper oxide nanoparticle-based tissue conditioner used in complete prostheses. METHODS: The present experimental study included 126 tissue conditioner samples with different concentrations of copper oxide nanoparticles (20%, 10%, 5%, 2.5%, 1.25%, 0.625%, and 0% w/w). The samples were incubated with Enterococcus faecalis, Pseudomonas aeruginosa, and Candida albicans in 24-well plates for 24 h. Then, samples from the wells were re-incubated for 24 h, and the microorganisms were counted. RESULTS: The culture media containing E. faecalis and P. aeruginosa showed significantly different growth between different nanoparticle concentrations following 24 h (P < 0.001), showing a reduction in bacterial growth with increased nanoparticle concentration. Both bacteria did not show any growth at the 20% concentration. However, C. albicans showed significant differences in growth between different nanoparticle concentrations following 48 h (P < 0.001), showing a reduction in growth with increased nanoparticle concentration. Also, the least growth was observed at the 20% concentration. CONCLUSIONS: In conclusion, the CuO nanoparticles were prepared using a green synthesis methon in the suitable sizes. Moreover, the tissue conditioners containing CuO nanoparticles showed acceptable antimicrobial properties against E. faecalis, P. aeruginosa, and C. albicans.

Comparative Evaluation of Antibacterial Efficacy, Molecular Docking of Ethanolic Extract of Blackseed, Seaweed and Calcium Hydroxide Intracanal Medicament with Enterococcus Faecalis Antigens.

Aim: To evaluate the inhibitory effect of ethanolic extract blackseed, seaweed, and calcium hydroxide intracanal medicament with Enterococcus faecalis biofilm. To study the binding interaction between the active components of blackseed and seaweed against the enterococcal surface protein of (E. faecalis) by molecular docking. Materials and Methods: The ethanolic extracts of blackseed and seaweed were prepared using the Soxhlet apparatus. They were divided into three groups, namely, |Group I: Calcium hydroxide, Group II: Blackseed, and Group III: Seaweed. The antibacterial activity of the three groups was detected employing various concentrations ranging from 250, 125, and 62.5 µg/ml and based on the zone of inhibition. The inhibitory potential of medicaments to inhibit E. faecalis growth at various stages and kinetics plate were assessed following biofilm architecture evaluation by crystal violet biofilm assay. With the Swissdock suite, the molecular docking procedure was carried out. PyMOL version 4.1.5 was the program used for visualization. Since enterococcal surface protein (Esp) is primarily involved in the formation of biofilms, it was chosen as the target protein of E. faecalis. Based on their chromatographic investigations, Group II Thymoquinone (TQ) and Group III Ledenoxide were chosen as ligands. Results: The percentage of inhibition of E. faecalis biofilm was analyzed as statistically significant observed within groups. On post-hoc analysis, significant differences were present between the groups (P < 0.05). Molecular docking reveals binding energies of thymoquinone (Group II) and ledenoxide (Group III) against the enterococcal surface protein of E. faecalis were -6.90 Kcal/mol and -6.44 Kcal/mol, respectively. Conclusion: Compared to seaweed, black seed extract exhibited higher antibacterial activity against the E. faecalis biofilm in microbial inhibition and molecular interaction.

Fe-S biogenesis by SMS and SUF pathways: A focus on the assembly step.

FeS clusters are prosthetic groups present in all organisms. Proteins with FeS centers are involved in most cellular processes. ISC and SUF are machineries necessary for the formation and insertion of FeS in proteins. Recently, a phylogenetic analysis on more than 10,000 genomes of prokaryotes have uncovered two new systems, MIS and SMS, which were proposed to be ancestral to ISC and SUF. SMS is composed of SmsBC, two homologs of SufBC(D), the scaffolding complex of SUF. In this review, we will specifically focus on the current knowledge of the SUF system and on the new perspectives given by the recent discovery of its ancestor, the SMS system.

Engineering of chimeric enzymes with expanded tolerance to ionic strength.

Antimicrobial resistance poses a significant global threat, reaching dangerously high levels as reported by the World Health Organization. The emergence and rapid spread of new resistance mechanisms, coupled with the absence of effective treatments in recent decades, have led to thousands of deaths annually from infections caused by drug-resistant microorganisms. Consequently, there is an urgent need for the development of new compounds capable of combating antibiotic-resistant bacteria. A promising class of molecules exhibiting potent bactericidal effects is peptidoglycan hydrolases. Previously, we cloned and characterized the biochemical properties of the M23 catalytic domain of the EnpA (EnpACD) protein from Enterococcus faecalis. Unlike other enzymes within the M23 family, EnpACD demonstrates broad specificity. However, its activity is constrained under low ionic strength conditions. In this study, we present the engineering of three chimeric enzymes comprising EnpACD fused with three distinct SH3b cell wall-binding domains. These chimeras exhibit enhanced tolerance to environmental conditions and sustained activity in bovine and human serum. Furthermore, our findings demonstrate that the addition of SH3b domains influences the activity of the chimeric enzymes, thereby expanding their potential applications in combating antimicrobial resistance.IMPORTANCEThese studies demonstrate that the addition of the SH3b-binding domain to the EnpACD results in generation of chimeras with a broader tolerance to ionic strength and pH values, enabling them to remain active over a wider range of conditions. Such approach offers a relatively straightforward method for obtaining antibacterial enzymes with tailored properties and emphasizes the potential for proteins' engineering with enhanced functionality, contributing to the ongoing efforts to address antimicrobial resistance effectively.

Multispecies bacterial invasion of human host cells.

Urinary tract infection (UTI), one of the most common bacterial infections worldwide, is a typical example of an infection that is often polymicrobial in nature. While the overall infection course is known on a macroscale, bacterial behavior is not fully understood at the cellular level and bacterial pathophysiology during multispecies infection is not well characterized. Here, using clinically relevant bacteria, human epithelial bladder cells and human urine, we establish co-infection models combined with high resolution imaging to compare single- and multi-species bladder cell invasion events in three common uropathogens: uropathogenic Escherichia coli (UPEC), Klebsiella pneumoniae and Enterococcus faecalis. While all three species invaded the bladder cells, under flow conditions the Gram-positive E. faecalis was significantly less invasive compared to the Gram-negative UPEC and K. pneumoniae. When introduced simultaneously during an infection experiment, all three bacterial species sometimes invaded the same bladder cell, at differing frequencies suggesting complex interactions between bacterial species and bladder cells. Inside host cells, we observed encasement of E. faecalis colonies specifically by UPEC. During subsequent dispersal from the host cells, only the Gram-negative bacteria underwent infection-related filamentation (IRF). Taken together, our data suggest that bacterial multispecies invasions of single bladder cells are frequent and support earlier studies showing intraspecies cooperation on a biochemical level during UTI.

Complete genome sequence of the linezolid-resistant clinical Enterococcus faecalis N23-3408 linked to a livestock lineage in Switzerland.

Here, we report the complete genome of human clinical linezolid-resistant Enterococcus faecalis N23-3408. N23-3408 harbored a 59.5 kb plasmid with antimicrobial resistance genes cat, erm(B), fexA, optrA, tet(L), and tet(M). Closely related E. faecalis harboring this plasmid was previously obtained from livestock animals and pet food in Switzerland.

Antibacterial Activity and Action Mechanism of Bacteriocin Paracin wx7 as a Selective Biopreservative against Vancomycin-Resistant Enterococcus faecalis in Fresh-Cut Lettuce.

Fresh-cut vegetables are widely consumed, but there is no food preservative available to selectively inhibit vancomycin-resistant E. faecalis, which is a serious health menace in fresh-cut vegetables. To develop a promising food biopreservative, a bacteriocin, paracin wx7, was synthesized, showing selective inhibition against E. faecalis with MIC values of 4-8 µM. It showed instant bactericidal mode within 1 h at high concentrations with concomitant cell lysis against vancomycin-resistant E. faecalis. Its lethal effect was visualized in a dose-dependent manner by PI/SYTO9 staining observation. The results of an in vivo control experiment carried out on E. faecalis in fresh-cut lettuce showed that 99.97% of vancomycin-resistant E. faecalis were dead after 64 µM paracin wx7 treatment for 7 days without influencing total bacteria. Further, the action mechanism of paracin wx7 was investigated. Confocal microscopy showed that paracin wx7 was located both on the cell envelope and in cytoplasm. For the cell envelope, the studies of membrane permeability using SYTOX Green dyeing and DNA leakage revealed that paracin wx7 damaged the membrane integrity of E. faecalis. Simultaneously, it exhibited membrane depolarization after analysis using DiSC3(5). Damage to the cell envelope resulted in cell deformation observed by scanning electron microscopy. On entering the cytoplasm, the paracin wx7 induced the production of endogenous reactive oxygen species.

Decoding the complexity of delayed wound healing following Enterococcus faecalis infection.

Wound infections are highly prevalent and can lead to delayed or failed healing, causing significant morbidity and adverse economic impacts. These infections occur in various contexts, including diabetic foot ulcers, burns, and surgical sites. Enterococcus faecalis is often found in persistent non-healing wounds, but its contribution to chronic wounds remains understudied. To address this, we employed single-cell RNA sequencing (scRNA-seq) on infected wounds in comparison to uninfected wounds in a mouse model. Examining over 23,000 cells, we created a comprehensive single-cell atlas that captures the cellular and transcriptomic landscape of these wounds. Our analysis revealed unique transcriptional and metabolic alterations in infected wounds, elucidating the distinct molecular changes associated with bacterial infection compared to the normal wound healing process. We identified dysregulated keratinocyte and fibroblast transcriptomes in response to infection, jointly contributing to an anti-inflammatory environment. Notably, E. faecalis infection prompted a premature, incomplete epithelial-mesenchymal transition in keratinocytes. Additionally, E. faecalis infection modulated M2-like macrophage polarization by inhibiting pro-inflammatory resolution in vitro, in vivo, and in our scRNA-seq atlas. Furthermore, we discovered macrophage crosstalk with neutrophils, which regulates chemokine signaling pathways, while promoting anti-inflammatory interactions with endothelial cells. Overall, our findings offer new insights into the immunosuppressive role of E. faecalis in wound infections.

If wounds get infected, they heal much more slowly, sometimes leading to skin damage and other complications, including disseminated infections or even amputation. Infections can happen in many types of wounds, ranging from ulcers in patients with diabetes to severe burns. If infections are not cleared quickly, the wounds can become 'chronic' and are unable to heal without intervention. Enterococcus faecalis is a type of bacteria that normally lives in the gut. Within that environment, in healthy people, it is not harmful. However, if it comes into contact with wounds ­ particularly diabetic ulcers or the site of a surgery ­ it can cause persistent infections and prevent healing. Although researchers are beginning to understand how E. faecalis initially colonises wounds, the biological mechanisms that transform these infections into chronic wounds are still largely unknown. Celik et al. therefore set out to investigate exactly how E. faecalis interferes with wound healing. To do this, Celik et al. looked at E. faecalis-infected wounds in mice and compared them to uninfected ones. Using a genetic technique called single-cell RNA sequencing, Celik et al. were able to determine which genes were switched on in individual skin and immune cells at the site of the wounds. This in turn allowed the researchers to determine how those cells were behaving in both infected and uninfected conditions. The experiments revealed that when E. faecalis was present in wounds, several important cell types in the wounds did not behave normally. For example, although the infected skin cells still underwent a change in behaviour required for healing (called an epithelial-mesenchymal transition), the change was both premature and incomplete. In other words, the skin cells in infected wounds started changing too early and did not finish the healing process properly. E. faecalis also changed the way macrophages and neutrophils worked within the wounds. These are cells in our immune system that normally promote inflammation, a process involved in both uninfected wounds or during infections and is a key part of wound healing when properly controlled. In the E. faecalis-infected wounds, these cells' inflammatory properties were suppressed, making them less helpful for healing. These results shed new light on how E. faecalis interacts with skin cells and the immune system to disrupt wound healing. Celik et al. hope that this knowledge will allow us to find new ways to target E. faecalis infections, and ultimately develop treatments to help chronic wounds heal better and faster.

Epidemiological trends and susceptibility patterns of bloodstream infections caused by Enterococcus spp. in six German university hospitals: a prospectively evaluated multicentre cohort study from 2016 to 2020 of the R-Net study group.

PURPOSE: To analyse recent epidemiological trends of bloodstream infections (BSI) caused by Enterococcus spp. In adult patients admitted to tertiary care centres in Germany. METHODS: Epidemiological data from the multicentre R-NET study was analysed. Patients presenting with E. faecium or E. faecalis in blood cultures in six German tertiary care university hospitals between October 2016 and June 2020 were prospectively evaluated. In vancomycin-resistant enterococci (VRE), the presence of vanA/vanB was confirmed via molecular methods. RESULTS: In the 4-year study period, 3001 patients with BSI due to Enterococcus spp. were identified. E. faecium was detected in 1830 patients (61%) and E. faecalis in 1229 patients (41%). Most BSI occurred in (sub-) specialties of internal medicine. The pooled incidence density of enterococcal BSI increased significantly (4.0-4.5 cases per 10,000 patient days), which was primarily driven by VRE BSI (0.5 to 1.0 cases per 10,000 patient days). In 2020, the proportion of VRE BSI was > 12% in all study sites (range, 12.8-32.2%). Molecular detection of resistance in 363 VRE isolates showed a predominance of the vanB gene (77.1%). CONCLUSION: This large multicentre study highlights an increase of BSI due to E. faecium, which was primarily driven by VRE. The high rates of hospital- and ICU-acquired VRE BSI point towards an important role of prior antibiotic exposure and invasive procedures as risk factors. Due to limited treatment options and high mortality rates of VRE BSI, the increasing incidence of VRE BSI is of major concern.

Interaction of selected alkoxy naringenin oximes with model and bacterial membranes.

Naringenin is a flavonoid found in many fruits and herbs, most notably in grapefruits. In recent years, this compound and its derivatives have been of great interest due to their high biological activity, including fungicidal and bactericidal effects, also in relation to multidrug-resistant bacteria. Membrane interactions of naringenin oxime (NO) and its 7-O-alkyl (7-alkoxy) derivatives, such as methyl (7MENO), ethyl (7ETNO), isopropyl (7IPNO), n-butyl (7BUNO) and n-pentyl (7PENO) were studied. Thermotropic properties of model membranes were investigated via differential scanning calorimetry (DSC), the influence on lipid raft mimicking giant unilamellar vesicles (GUVs) via fluorescence microscopy, and membrane permeability via measuring calcein leakage from liposomes. Molecular calculations supplemented the study. The influence of naringenin oximes on two strains of multidrug resistant bacteria: Staphylococcus aureus KJ and Enterococcus faecalis 37VRE was also investigated. In DSC studies all compounds reduced the temperature and enthalpy of main phase transition and caused disappearing of the pretransition. NO was the least active. The reduction in the area of surface domains in GUVs was observed for NO. Compounds NO and 7BUNO resulted in very low secretion of calcein from liposomes (permeability < 3 %). The highest results were observed for 7MENO (88.4 %) and 7IPNO (78.5 %). When bacterial membrane permeability was investigated all compounds caused significant release of propidium iodide from S. aureus (31.6-87.0 % for concentration 128 µg/mL). In the case of E. faecalis, 7ETNO (75.7 %) and NO (28.8 %) were the most active. The rest of the tested compounds showed less activity (permeability < 13.9 %). The strong evidence was observed that antibacterial activity of the tested compounds may be associated with their interaction with bacterial membrane.

Evaluation of Antimicrobial Effectiveness of Root Canal Sealers Modified with Various Herbal Extracts against Candida Albicans and E Faecalis.

Objectives: The aim of the study was to assess the effectiveness of ZOE-based, calcium hydroxide, and epoxy resin-based sealers on modification with three herbal extracts. Materials and Methods: Methanolic extracts of selected herbs were combined with ZOE-based, calcium hydroxide, and epoxy resin-based sealers. Cultures were prepared from E. faecalis and C. albicans and agar plates prepared. Prepared mixtures were inoculated in punched holes, and inhibitory zones were measured. Results: No statistical significance was obtained on comparing mean scores of test groups. Conclusion: None of the combinations used was found to be significantly better than others.

Enhancing Antimicrobial Efficacy and Synergistic Effects of Nano-Silica-Based Combinations With Doxycycline, Metronidazole, and Ciprofloxacin Against Enterococcus faecalis Biofilms.

BACKGROUND:  Enterococcus faecalis biofilm formation within root canals poses a challenging problem in endodontics, often leading to treatment failure. To combat this issue, nanotechnology offers a promising avenue for enhancing antimicrobial efficacy. This study explores the potential synergistic effects of combining nanoscale silica particles with conventional antibiotics, including doxycycline, metronidazole, and ciprofloxacin, against E. faecalis biofilms. The unique characteristics of silica nanoparticles, such as their increased reactivity and ability to be functionalized with other compounds, make them ideal candidates for augmenting antibiotic efficacy. This research investigates the antimicrobial properties of these silica-based combinations and their potential to eliminate or inhibit E. faecalis biofilms more effectively than conventional treatments.  Methodology: The methods involved the preparation of nanostructured silica particles and their combination with doxycycline, Flagyl, and ciprofloxacin at subinhibitory concentrations. These combinations were then tested against E. faecalis biofilms using the agar well diffusion technique. RESULTS: Preliminary results suggested that the synergistic interactions between silica nanoparticles and antibiotics can significantly enhance antimicrobial efficacy. The combined treatment exhibited superior inhibitory effects on E. faecalis compared to antibiotics or silica nanoparticles alone (P < 0.05).  Conclusions: This study sheds light on the potential of nanoscale silica-based combinations to address the challenges posed by E. faecalis biofilms in endodontics. Understanding the mechanisms of synergy between nanoparticles and antibiotics can pave the way for the development of more effective and targeted strategies for root canal disinfection, ultimately improving the success rates of endodontic treatments.

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.

The Effect of Different Compositions and Concentrations of Etidronate-Containing Irrigants on the Antibacterial Activity of Sodium Hypochlorite against Enterococcus faecalis and Candida albicans.

We assessed the effect of different compositions and concentrations of two etidronate-containing irrigants on the antibacterial activity of sodium hypochlorite (SH) against Enterococcus faecalis and Candida albicans in vitro. Pure cultures of C. albicans and E. faecalis were isolated from root canal samples. The disc diffusion method was used to compare the antibacterial effect of pure SH and SH mixed with 9%, 15%, and 18% etidronate of two manufactures (dual rinse (DR); IsraDent (ID)) and EDTA. The pH and temperature of the solutions were measured immediately after mixing and within 40 min. The ANOVA revealed a significant influence of the type of irrigating solution on the C. albicans and E. faecalis inhibition zone diameters that ranged from 6.6 to 51.6 mm and from 6.4 to 12.4 mm, respectively. SH with DR 9% exhibited the highest effect against C. albicans. The antifungal activity of the other irrigants was SH = SH + DR15% = SH + DR18% = SH + ID9% > SH + EDTA > SH + ID15% > SH + ID18%. No significant differences in the anti-E. faecalis effect were revealed between the tested solutions except for the mixtures of SH and 15% and 18% ID, which exhibited no antiseptic effect. There was a strong positive correlation between antiseptic activity against both microorganisms and the pH values of the tested solutions. In conclusion, most etidronate formulations did not significantly hamper sodium hypochlorite activity against C. albicans and E. faecalis. The effect was concentration- and manufacturer-dependent.

Antimicrobial Resistance in Enterococcus spp. Isolates from Red Foxes (Vulpes vulpes) in Latvia.

Antimicrobial resistance (AMR) is an emerging public health threat and is one of the One Health priorities for humans, animals, and environmental health. Red foxes (Vulpes vulpes) are a widespread predator species with great ecological significance, and they may serve as a sentinel of antimicrobial resistance in the general environment. The present study was carried out to detect antimicrobial resistance, antimicrobial resistance genes, and genetic diversity in faecal isolates of red foxes (Vulpes vulpes). In total, 34 Enterococcus isolates, including E. faecium (n = 17), E. faecalis (n = 12), E. durans (n = 3), and E. hirae (n = 2), were isolated. Antimicrobial resistance to 12 antimicrobial agents was detected with EUVENC panels using the minimum inhibitory concentration (MIC). The presence of antimicrobial resistance genes (ARGs) was determined using whole-genome sequencing (WGS). Resistance to tetracycline (6/34), erythromycin (3/34), ciprofloxacin (2/34), tigecycline (2/34), and daptomycin (2/34) was identified in 44% (15/34) of Enterococcus isolates, while all the isolates were found to be susceptible to ampicillin, chloramphenicol, gentamicin, linezolid, teicoplanin, and vancomycin. No multi-resistant Enterococcus spp. were detected. A total of 12 ARGs were identified in Enterococcus spp., with the presence of at least 1 ARG in every isolate. The identified ARGs encoded resistance to aminoglycosides (aac(6')-I, ant(6)-Ia, aac(6')-Iih and spw), tetracyclines (tet(M), tet(L) and tet(S)), and macrolide-lincosamide-streptogramin AB (lnu(B,G), lsa(A,E), and msr(C)), and their presence was associated with phenotypical resistance. Core genome multilocus sequence typing (cgMLST) revealed the high diversity of E. faecalis and E. faecium isolates, even within the same geographical area. The distribution of resistant Enterococcus spp. in wild foxes in Latvia highlights the importance of a One Health approach in tackling AMR.

Comparación de la actividad antimicrobiana de cementos selladores en endodoncia / Comparison of the antimicrobial activity of sealing cements in endodontics

Introducción: la persistencia de microorganismos en los conductos radiculares es uno de los principales factores del fracaso endodóncico. Por ello la importancia de conocer las propiedades antimicrobianas de los distintos tipos de selladores. Objetivo: realizar una comparación con base en la evidencia disponible sobre la actividad antimicrobiana de los diferentes cementos selladores en endodoncia. Material y métodos: la información fue recopilada de las bases de datos PubMed y Google Académico en el idioma inglés y español, publicados en el periodo 2014-2023. Resultados: un gran número de microorganismos se encuentran presentes en los diferentes tipos de infecciones de origen endodóncico, se han identificado más de 500 especies microbianas, entre ellas bacterias, hongos, arqueas y virus. Los cementos selladores se pueden clasificar según su composición química, en cementos a base de óxido de zinc-eugenol, hidróxido de calcio, a base de ionómero de vidrio, silicona, resina y biocerámicos. Conclusión: los cementos selladores que mostraron mayor actividad antimicrobiana contra los microorganismos persistentes fueron los cementos a base de óxido de zinc-eugenol, resina y biocerámicos. Sin embargo, se identificó que cada autor utilizó diferentes métodos y tiempos, por lo tanto, no es posible lograr definir con exactitud qué cemento sellador posee la mejor capacidad antimicrobiana (AU)

Introduction: the persistence of microorganisms in root canals is one of the main factors of endodontic failure. Therefore, the importance of knowing the antimicrobial properties of the different types of sealants. Objective: to make a comparison based on the available evidence on the antimicrobial activity of the different endodontics sealers. Material and methods: the information was collected from PubMed and Google Academic databases in English and Spanish, published in the period 2014-2023. Results: a large number of microorganisms are present in the different types of infections of endodontic origin, more than 500 microbiological species have been identified, including bacteria, fungi, archaea and viruses. Sealer cements can be classified according to their chemical composition, into cements based on zinc oxide-eugenol, calcium hydroxide, based on glass ionomer, silicone, resin and bioceramics. Conclusion: sealer cements that showed the highest antimicrobial activity against persistent microorganisms were zinc oxide-eugenol, resin, and bioceramic-based cements. However, it was identified that each author used different methods and times, therefore, it is not possible to accurately define which sealer cement has the best antimicrobial capacity (AU)

The effect of the enzymes trypsin and DNase I on the antimicrobial efficiency of root canal irrigation solutions.

The purpose of this study was to evaluate the antibacterial efficacy of using 2.5% NaOCl, 2% chlorhexidine (CHX), Irritrol, and chitosan-coated silver nanoparticles (AgCNPs) alone or in combination with deoxyribonuclease I (DNase I) and trypsin pre-enzyme applications in dentin samples contaminated with Enterococcus faecalis (E. faecalis) by CLSM. 144 dentin blocks with confirmed E. faecalis biofilm formation were divided randomly according to the irrigation protocol (n = 12): NaOCl, CHX, Irritrol, AgCNPs, trypsin before NaOCl, CHX, Irritrol, AgCNPs, and DNase I before NaOCl, CHX, Irritrol, AgCNPs. Dentin blocks were stained with the Live/Dead BacLight Bacterial Viability Kit and viewed with CLSM after irrigation applications. The percentage of dead and viable bacteria was calculated using ImageJ software on CLSM images. At a significance level of p < 0.05, the obtained data were analyzed using one-way Anova and post-hoc Tukey tests. In comparison with NaOCl, CHX had a higher percentage of dead bacteria, both when no pre-enzyme was applied and when DNase I was applied as a pre-enzyme (p < 0.05). There was no difference in the percentage of dead bacteria between the irrigation solutions when trypsin was applied as a pre-enzyme (p > 0.05). AgCNPs showed a higher percentage of dead bacteria when trypsin was applied as a pre-enzyme compared to other irrigation solutions (p < 0.05), while the pre-enzyme application did not affect the percentage of dead bacteria in NaOCl, CHX, and Irritrol (p > 0.05). No irrigation protocol tested was able to eliminate the E. faecalis biofilm. While the application of trypsin as a pre-enzyme improved the antimicrobial effect of AgCNPs, it did not make any difference over other irrigation solutions.