ARTICLE | doi:10.20944/preprints202010.0162.v1
Subject: Medicine & Pharmacology, Allergology Keywords: biofilm; Candida albicans; E-cadherin; Enterococcus faecalis; FISH; oral mucosa.
Online: 8 October 2020 (08:20:36 CEST)
Candida albicans as an opportunistic pathogen exploits the host immune system and causes a variety of life-threatening infections. The polymorphic nature of this fungus gives it tremendous advantage to breach mucosal barriers and cause a variety of oral and disseminated infections. Enterococcus faecalis, another opportunistic pathogen co-exists with C. albicans in several niches in the human body, including the oral cavity and gastrointestinal tract. However, interactions between E. faecalis and C. albicans on oral mucosal surfaces remain unknown. Here, for the first time, we comprehensively characterized the interactive profiles between laboratory and clinical isolates of C. albicans (SC5314 and BF1) and E. faecalis (OG1RF and 846) on an organotypic oral mucosal model. Our results demonstrated that the two species formed robust biofilms on the mucosal tissue surface with profound surface erosion and fungal invasion. Specifically, this effect was more pronounced in the laboratory isolates than in the clinical isolates. Notably, several genes of C. albicans involved in tissue adhesion, hyphal formation, fungal invasion, and biofilm formation were significantly upregulated in the presence of E. faecalis. This study highlights the strain-dependent cross-kingdom interactions between E. faecalis and C. albicans on oral mucosa, demonstrating the requisite to study more substrate-dependent polymicrobial interactions.
ARTICLE | doi:10.20944/preprints202009.0758.v1
Subject: Life Sciences, Biochemistry Keywords: Enterococcus faecalis; Proteus mirabilis; Polymicrobial; Biofilm; Catheter; Urinary Tract Infection
Online: 30 September 2020 (16:39:51 CEST)
Indwelling urinary catheters are common in healthcare settings and can lead to catheter-associated urinary tract infection (CAUTI). Long-term catheterization causes polymicrobial colonization of the catheter and urine, for which the clinical significance is poorly understood. Through prospective assessment of catheter urine colonization, we identified Enterococcus faecalis and Proteus mirabilis as the most prevalent and persistent co-colonizers. Clinical isolates of both species successfully co-colonized in a murine model of CAUTI, and they were observed to co-localize on catheter biofilms during infection. We further demonstrate that P. mirabilis preferentially adheres to E. faecalis during biofilm formation, and that contact-dependent interactions between E. faecalis and P. mirabilis facilitate establishment of a robust biofilm architecture that enhances antimicrobial resistance for both species. E. faecalis may therefore act as a pioneer species on urinary catheters, establishing an ideal surface for persistent colonization by more traditional pathogens such as P. mirabilis.
ARTICLE | doi:10.20944/preprints202211.0132.v1
Subject: Chemistry, Medicinal Chemistry Keywords: Enterococcus faecalis; natural products; aminoglycosides; aminoglycoside-modifying enzymes; APH(3’)-IIIa; flavone derivative
Online: 8 November 2022 (01:39:19 CET)
Enterococcus faecalis is a bacterium that can develop a multidrug resistance profile associated with the community as well as nosocomial-acquired infections. Among the treatment options for these infections are aminoglycosides combined with bacterial cell wall inhibitors such as beta-lactams, since E. faecalis is intrinsically resistant to aminoglycosides. One of its most representative resistance mechanisms is the expression of aminoglycoside-modifying enzymes, such as the aminoglycoside phosphotransferase type IIIa of E. faecalis (EfAPH(3')-IIIa). This enzyme acts by phosphorylating aminoglycosides in an ATP-dependent reaction, modifying the 3' position of hydroxyl groups of these antibiotics. Considering this scenario, 3,092 natural products obtained from the ZINC22 database were analyzed to select molecules with the highest affinity for the nucleotide-binding pocket of EfAPH(3')-IIIa, which could be potential aminoglycoside adjuvants. The molecules that showed the best-score results obtained from ensemble docking-based virtual screening were ZINC000000952700 (BS-1), ZINC000014793040 (BS-2) and ZINC000015498603 (BS-3). The most promising results were for BS-2, a flavone derivative, due to its improved stability profile in molecular dynamics simulation (average values of RMSD of 0.23 nm, and Rg of 1.94 nm), binding free energy calculations (average ΔG total of -35.3 nm), as well as better toxicological profile (lower probability of hepatotoxicity, carcinogenic, immunotoxicity, mutagenicity, and cytotoxicity effects), compared to BS-1 and BS-3. These results allow us to propose that a flavone derivative may act as an adjuvant to aminoglycosides in the treatment of E. faecalis infections, acting as an inhibitor in the nucleotide-binding pocket of EfAPH(3')-IIIa.
ARTICLE | doi:10.20944/preprints202105.0304.v2
Subject: Life Sciences, Microbiology Keywords: Enterococcus; QPS; GRAS; safety; milk; cheese; mountain area
Online: 19 August 2021 (06:31:01 CEST)
The latest EU regulation on geographical indications (EU Regulation No. 1151/2012) has intro-duced a set of new tools for the protection and enhancement of food products in rural areas, under the group name of optional quality term (OQT). The Commission Delegated EU Regulation, No. 665/2014, regulated the conditions for the use of the optional quality term «mountain product» (MP), to support the implementation of a mountain value chain. This new tool is aimed at pro-moting local development, maintaining the economic activities in mountain areas and redistrib-uting wealth, whilst, at the same time, promoting the territory. Pecorino and goat cheeses are typ-ical Italian cheeses made usually with whole raw ewe's or raw goat's milk, without starter cul-ture addition. In an attempt to characterize these productions, the aim of this study was to inves-tigate the evolution of enterococci during the production and ripening of Pecorino cheese made in three different farms, located in Umbria, Italy in areas facing natural or other specific constraints as stipulated by Regulation 1305/2013 on support for rural development by the European Agri-cultural Fund for Rural Development (EAFRD). Enterococci are enteric organisms which are commonly isolated from ewe and goat's milk production in Umbria, Italy. Counts of enterococci in raw milk ranged from 1.75 for ovine milk to 3.62 for ewe milk and a marked reduction was observed after thermization especially in ovine milk. Out of 100 isolates, 69 were E. faecium, 23 E. durans, 8 E. faecalis and 2 E. casseliflavus and the distribution of species between farms and be-tween samples showed a prevalence of E. faecium in ovine farms and E. durans in ewes farms, with an equal distribution between samples. High percentages of susceptible isolates were found for amoxicillin/clavulanic acid, ampicillin, chloramphenicol, sulphamethoxazole, sulphameth-oxazole/trimethoprim, ticarcillin, vancomycin. A high prevalence of resistant strains (> 30%) was observed for amikacin, ciprofloxacin, ceftriaxone, kanamycin, tetracycline. A comparison of this results with those of previous works on similar dairy products revealed high levels of resistance to antimicrobials which needs to be addressed.
ARTICLE | doi:10.20944/preprints202111.0474.v1
Subject: Life Sciences, Microbiology Keywords: probiotic; Enterococcus faecium; antimicrobial resistance; environmental change
Online: 25 November 2021 (12:49:29 CET)
In two sequential replicates (n=90 and n=96 feedlot finisher cattle, respectively) we measured the impact of an Enterococcus faecium-based probiotic (DFM) and an altered feedlot pen environment on antimicrobial resistance among fecal enterococci in cattle fed (or, not fed) the macrolide tylosin. Diluted fecal samples were spiral-plated on plain and antibiotic-supplemented m-Enterococcus agar. In the first replicate, tylosin significantly (p<0.05) increased the relative quantity of erythromycin-resistant enterococci. This effect was diminished in cattle fed the DFM in conjunction with tylosin. A similar observed effect was not statistically significant (P > 0.05) in the second replicate. Isolates were speciated and resistance phenotypes were obtained for E. faecium and E. hirae. E. faecium isolates were whole-genome sequenced, which yielded sequence types (ST), resistance genes and phylogeny. Samples of the DFM were sequenced and found to contain E. faecium ST296, which was not present on Day 0 of either replicate. This DFM sequence type was found in fecal samples after Day 0, the majority of which were isolated from cattle in one of the DFM-fed pens. Increased prevalence of ST296 occurred with a concomitant decrease in ST240; of importance, the latter typically harbored both ermB and tet(M) genes.
ARTICLE | doi:10.20944/preprints202101.0481.v1
Subject: Materials Science, Biomaterials Keywords: Antibacterial activity; Endodontic irrigant; Enterococcus faecalis; Quercetin; Root canal
Online: 25 January 2021 (10:54:58 CET)
(1) Background: Bacterial reinfection and root fracture are the main culprits related to root canal treatment failure. This study aimed to assess the utility of quercetin solution as an adjunctive endodontic irrigant that strengthen root canal dentin with commitment anti-biofilm activity and bio-safety. (2) Methods: Based on a noninvasive dentin infection model, dentin tubules infected with Enterococcus faecalis (E. faecalis) were irrigated with sterile water (control group), and 0, 1, 2, 4 wt% quercetin-containing ethanol solutions. The live and dead bacteria proportions within E. fae-calis biofilms were analyzed using confocal laser scanning microscopy (CLSM). Elastic modulus and hydroxyproline release and X-ray photoelectron spectroscopy (XPS) characterization was tested on irrigant-treated demineralized dentin to evaluate irrigants’ biostability. The cytotoxicity of irrigants was tested by CCK-8 assay. (3) Results: Quercetin increased the proportion of dead bacteria volumes within E. faecalis, and improved the flexural strength of dentin collagen com-pared to control group. The XPS characterization revealed an increase in C-O peak area under both C1s and O1s narrow-scan spectra. The CCK-8 assay confirmed no cytotoxicity of quercetin solutions. (4) Conclusions: Quercetin exhibited anti-biofilm activity, collagen-stabilizing effect as well as cytocompatibility, supporting quercetin as a potential candidate for endodontic irrigant.
REVIEW | doi:10.20944/preprints202007.0393.v1
Subject: Life Sciences, Microbiology Keywords: Enterococcus; antibiotic resistance; vancomycin resistance; public health; nosocomial opportunists
Online: 17 July 2020 (15:32:54 CEST)
Enterococci are gastrointestinal commensals whose hardiness allowed them to colonize very diverse environments, including soils, water, food and feed. This ability to overcome adverse conditions makes enterococci problematic once they colonize hospital niches. Together with the malleability of their genomes, the capacity to acquire and disseminate determinants of antibiotic resistance have contributed to convert what was once just another opportunistic pathogen into a first-class clinical problem. This review discusses the dimension of the emergence of enterococcal resistance to key antimicrobial agents, the dissemination of this resistance and its significance in terms of public health, with the aim of raising the awareness to the need to devise and implement monitoring programmes and effective antibiotic usage guidelines.
ARTICLE | doi:10.20944/preprints202111.0540.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: Probiotics; Dysbiosis; Obesity; High Fat Diet; Lactobacillus plantarum; Enterococcus faecium
Online: 29 November 2021 (12:59:43 CET)
Fat reduction and anti-inflammation are commonly claimed properties of probiotics. Lactobacillus plantarum and Enterococcus faecium were tested in high fat-induced obesity mice and in vitro experiments. After 16 weeks of probiotics, L. plantarum outperforms E. faecium on the anti-obesity property as indicated by body weight, regional fat accumulation, serum cholesterol, inflammatory cytokines (in blood and colon tissue), and gut barrier defect (FITC-dextran assay). With fecal microbiome analysis, L. plantarum but not E. faecium reduced fecal abundance of pathogenic Proteobacteria without an alteration in total Gram-negative bacteria when compared with non-probiotics obese mice. With palmitic acid induction, the condition media from both probiotics similarly attenuated supernatant IL-8, improved enterocyte integrity and down-regulated cholesterol absorption-associated genes in Caco-2 cell (an enterocyte cell line) and reduced supernatant cytokines (TNF-α and IL-6) with normalization of cell energy status (extracellular flux analysis) in bone-marrow-derived macrophages. Because the anti-inflammatory effect of the condition media of both probiotics on palmitic acid-activated enterocytes was neutralized by amylase, the active anti-inflammatory molecules might, partly, be exopolysaccharides. As L. plantarum out-performed E. faecium in anti-obesity property, possibly through the reduced fecal Proteobacteria, with a similar anti-inflammatory exopolysaccharide; L. plantarum is a potentially better option for anti-obesity than E. faecium.
ARTICLE | doi:10.20944/preprints202103.0225.v1
Subject: Medicine & Pharmacology, Allergology Keywords: Allergic rhinitis; Probiotics; Bifidobacterium animalis subsp lactis BB12; Enterococcus faecium L3; children
Online: 8 March 2021 (13:47:51 CET)
BACKGROUND: Probiotics may prevent the allergic response’s development due to their anti-inflammatory and immunomodulatory effects. The aim of this study is to determine if the prophylactic treatment with a mixture of Bifidobacterium animalis subsp. Lactis BB12 and Enterococcus faecium L3, would reduce symptoms and need for drug use in children with allergic rhinitis (AR). METHODS: The study included 250 children aged from 6 to 17 years, affected by AR. Patients were randomly assigned to the intervention group (117) or to the placebo group (86). Patients of the intervention group, in addition to conventional therapy (local corticosteroids and/or antihistamines), were treated, in the 3 months preceding the development of AR symptoms, with a daily oral administration of a probiotic mixture containing the Bifidobacterium animalis subsp Lactis BB12 DSM 15954 and the Enterococcus faecium L3 LMG P-27496 strain. Nasal Symptoms Score(NSS) was used to evaluate AR severity before and after the treatment with probiotics or placebo. RESULTS: 96% of the patients in the intervention group showed a significant decrease in their NSS after the probiotic treatment as well as a decrease in the intake of pharmacological therapy. GPower software was used to calculate the test power. Given the probability of error α = 0.05, the total sample size n = 117 and the effect size ρ = 2.0651316, the power of the test is 1 - β = 1. CONCLUSIONS: When administered as a prophylactic treatment the mixture of BB12 and L3 statistically decrease signs and symptoms of AR and reduces significantly the need of drugs.
ARTICLE | doi:10.20944/preprints202010.0242.v1
Subject: Medicine & Pharmacology, Allergology Keywords: lactic acid bacteria; enterococcus faecalis; dispersion; viral infection; particle size; Peyer's patch
Online: 12 October 2020 (13:09:21 CEST)
We evaluated the change in water dispersibility of lactic acid bacteria (LAB, Enterococcus faecalis KH2) upon powderization and its influence on their efficacy. When cultured LAB are washed, heat-killed, and powdered, adhesion between LAB occurs and they form aggregation (non-treated LAB, n-LAB). However, a dispersed LAB (d-LAB) powder with less aggregates can be prepared by treating them with a high-pressure homogenizer and adding an excipient during powdering. n-LAB or d-LAB was administered to mice and the Peyer's patches in the small intestine were observed. n-LAB administration showed a high amount of aggregated LAB drifting in the intestinal mucosa, whereas d-LAB reached the Peyer's patches and was taken up into the Peyer's patches. Evaluation in a mouse influenza virus infection model showed that d-LAB was more effective than n-LAB in influenza yield of bronchoalveolar lavage fluids (BALFs) on day 3 post-infection, neutralizing antibody titers of sera and influenza virus-specific IgA in the feces on day 14 post-infection. Thus, the physical properties of LAB affect their efficacy; controlling their water dispersibility can improve their effectiveness.
ARTICLE | doi:10.20944/preprints202108.0081.v1
Subject: Life Sciences, Biochemistry Keywords: heteroaromatic stilbene derivatives; antimicrobial activity; Staphylococcus aureus; Enterococcus faecalis; Escherichia coli; Pseudomonas aeruginosa; Acinetobacter baumannii; Klebsiella pneumoniae.
Online: 3 August 2021 (13:32:14 CEST)
The widespread use of antibiotics has led to a gradual increase in drug-resistant bacterial infections, which severely weakens the clinical efficacy of antibacterial therapies. In recent decades, stilbenes aroused great interest because of their high bioavailability, as well as for their manifold biological activity. Our research efforts are focused on synthetic heteroaromatic stilbene deriva-tives as they represent a potentially new type of antibiotic with a wide antibacterial spectrum. Herein, a preliminary molecular modeling study and a versatile synthetic scheme allowed us to define eight heteroaromatic stilbene derivatives with potential antimicrobial activity. In order to evaluate our compound’s activity spectrum and antibacterial ability, Minimum Inhibitory Con-centration (MIC) and Minimum Bactericidal Concentration (MBC) tests have been performed on Gram-positive and Gram-negative ATCC strains. Compounds PB4, PB5, PB7 and PB8 showed the best values in terms of MIC and were also evaluated for MBC, which however was found to be greater than MIC, confirming a bacteriostatic activity. For all compounds, we evaluated toxici-ty on colon-rectal adenocarcinoma cells tumor cells (CaCo2), once established that the whole se-lected set was more active than 5-Fluorouracil in reducing CaCo-2 cells viability. To the best of our knowledge, the biological assays have shown for these derivatives an excellent bacteriostatic activity, compared to similar molecular structures previously reported, thus paving the way for a new class of antibiotic compounds.
ARTICLE | doi:10.20944/preprints202209.0488.v1
Subject: Medicine & Pharmacology, Nutrition Keywords: carrot juice; human gut microbiota; fermentation; prebiotic; lactate; Lactobacillus fermentum; Lactobacillus salivarius; Lactobacillus mucosae; Bacteroides uniformis; Enterococcus faecium
Online: 30 September 2022 (11:19:07 CEST)
Carrot juice and its associated beverage products are well-known healthy drinks all over the world. However, what effect carrot juice has on the human gut microbiota and how it is fermented by the intestinal microbes have not been studied. Here, using an in vitro model of anaerobic fermentation, we demonstrated that carrot juice could be fermented into lactate and acetate by the human gut microbiota. 16S high-throughput sequencing and bioinformatic analyses indicated that fermentation of carrot juice could significantly change the composition of the human gut microbiome. Interestingly, carrot juice remarkably increased the abundances of beneficial bacteria, including Lactobacillus fermentum, Lactobacillus salivarius, Lactobacillus mucosae and Bacteroides uniformis and decreased the population of opportunistic pathogenic bacteria, such as Enterococcus faecium in the gut. Collectively, our study illustrates a favorable effect of carrot juice on the human gut microbiota and lays a foundation for the development of carrot juice as a novel prebiotic agent.