Multidrug-resistant Enterococcus Faecium Research Articles

A Versatile Thioesterase Involved in Dimerization during Cinnamoyl Lipid Biosynthesis.

The cinnamoyl lipid compound youssoufene A1 (1), featuring a unique dearomatic carbon-bridged dimeric skeleton, exhibits increased inhibition against multidrug resistant Enterococcus faecalis as compared to monomeric youssoufenes. However, the formation process of this intriguing dearomatization/dimerization remains unknown. In this study, an unusual "gene-within-gene" thioesterase (TE) gene ysfF was functionally characterized. The gene was found to naturally encodes two proteins, an entire YsfF with α/β-hydrolase and 4-hydroxybenzoyl-CoA thioesterase (4-HBT)-like enzyme domains, and a nested YsfFHBT (4-HBT-like enzyme). Using an intracellular tagged carrier-protein tracking (ITCT) strategy, in vitro reconstitution and in vivo experiments, we found that: i) both domains of YsfF displayed thioesterase activities; ii) YsfF/YsfFHBT could accomplish the 6π-electrocyclic ring closure for benzene ring formation; and iii) YsfF and cyclase YsfX together were responsible for the ACP-tethered dearomatization/dimerization process, possibly through an unprecedented Michael-type addition reaction. Moreover, site-directed mutagenesis experiments demonstrated that N301, E483 and H566 of YsfF are critical residues for both the 6π-electrocyclization and dimerization processes. This study enhances our understanding of the multifunctionality of the TE protein family.

A Versatile Thioesterase Involved in Dimerization during Cinnamoyl Lipid Biosynthesis

AbstractThe cinnamoyl lipid compound youssoufene A1 (1), featuring a unique dearomatic carbon‐bridged dimeric skeleton, exhibits increased inhibition against multidrug resistant Enterococcus faecalis as compared to monomeric youssoufenes. However, the formation process of this intriguing dearomatization/dimerization remains unknown. In this study, an unusual “gene‐within‐gene” thioesterase (TE) gene ysfF was functionally characterized. The gene was found to naturally encodes two proteins, an entire YsfF with α/β‐hydrolase and 4‐hydroxybenzoyl‐CoA thioesterase (4‐HBT)‐like enzyme domains, and a nested YsfFHBT (4‐HBT‐like enzyme). Using an intracellular tagged carrier‐protein tracking (ITCT) strategy, in vitro reconstitution and in vivo experiments, we found that: i) both domains of YsfF displayed thioesterase activities; ii) YsfF/YsfFHBT could accomplish the 6π‐electrocyclic ring closure for benzene ring formation; and iii) YsfF and cyclase YsfX together were responsible for the ACP‐tethered dearomatization/dimerization process, possibly through an unprecedented Michael‐type addition reaction. Moreover, site‐directed mutagenesis experiments demonstrated that N301, E483 and H566 of YsfF are critical residues for both the 6π‐electrocyclization and dimerization processes. This study enhances our understanding of the multifunctionality of the TE protein family.

Multidrug-resistant Enterococcus faecium strains enter the Norwegian marine environment through treated sewage.

This study aimed to understand the antibiotic resistance prevalence among Enterococcus spp. from raw and treated sewage in Bergen city, Norway. In total, 517 Enterococcus spp. isolates were obtained from raw and treated sewage from five sewage treatment plants (STPs) over three sampling occasions, with Enterococcus faecium as the most prevalent (n = 492) species. E. faecium strains (n = 307) obtained from the influent samples, showed the highest resistance against quinupristin/dalfopristin (67.8%). We observed reduced susceptibility to erythromycin (30.6%) and tetracycline (6.2%) in these strains. E. faecium strains (n = 185) obtained from the effluent samples showed highest resistance against quinupristin/dalfopristin (68.1%) and reduced susceptibility to erythromycin (24.9%) and tetracycline (8.6%). We did not detect resistance against last-resort antibiotics, such as linezolid, vancomycin, and tigecycline in any of the strains. Multidrug-resistant (MDR) E. faecium strains were detected in both influent (2.3%) and effluent (2.2%) samples. Whole genome sequencing of the Enterococcus spp. strains (n = 25) showed the presence of several antibiotic resistance genes, conferring resistance against aminoglycosides, tetracyclines, and macrolides, as well as several virulence genes and plasmid replicons. Two sequenced MDR strains from the effluents belonged to the hospital-associated clonal complex 17 and carried multiple virulence genes. Our study demonstrates that clinically relevant MDR Enterococcus spp. strains are entering the marine environment through treated sewage.

Inhibiting Peptidoglycan Hydrolase Alleviates MRSA Pneumonia Through Autolysin-Mediated MDP-NOD2 Pathway.

Methicillin-resistant Staphylococcus aureus (MRSA) is a cause of staph infection that is difficult to treat because of resistance to some antibiotics. A recent study indicated that diarylurea ZJ-2 is a novel antibacterial agent against multi-drug resistant Enterococcus faecium. In this work, we refined the bactericidal mechanism of ZJ-2 as a peptidoglycan (PG) hydrolase by affecting AtlA-mediated PG homeostasis. A wild-type strain (WT) and a mutant strain (ΔatlA) were used to investigate the effects of ZJ-2 on the cell wall, PG, and autolysin regulatory system by antimicrobial susceptibility testing, hemolytic toxin assay, microanalysis, autolysis assay, qRT-PCR, ELISA and mouse model of pneumonia. The results revealed that ZJ-2 down-regulated the expression of genes related to peptidoglycan hydrolase (PGH) (sprX, walR, atlA, and lytM), and reduced the levels of PG, muramyl dipeptide (MDP), cytokines, and hemolytic toxin, while ΔatlA interfered with the genes regulation and PG homeostasis. In the mouse MRSA pneumonia model, the same trend was observed in the nucleotide oligomerization domain protein 2 (NOD2) and relative proinflammatory factors. ZJ-2 may act as a novel inhibitor of PG hydrolyse, disrupting autolysin-mediated PG homeostasis, and reducing inflammation by down-regulating the MDP-NOD2 pathway.

Comparative study on Antibacterial efficacy of a series of chromone sulfonamide derivatives against drug-resistant and MDR-isolates.

Sulfonamide derivatives have numerous pharmaceutical applications having antiviral, antibacterial, antifungal, antimalarial, anticancer, and antidepressant activities. The structural flexibility of sulfonamide derivatives makes them an excellent candidate for the development of new multi-target agents, although long-time exposure to sulfonamide drugs results in many toxic impacts on human health. However, sulfonamides may be functionalized for developing less toxic and more competent drugs. In this work, sulfonamides including Sulfapyridine (a), Sulfathiazole (b), Sulfamethoxazole (c), and Sulfamerazine (d) are used to synthesize Schiff bases of 7-hydroxy-4-methyl-2-oxo-2H-chromene-8-carbalde-hyde (1a-1d). The synthesized compounds were spectroscopically characterized and tested against hospital isolates of three Gram-positive (Methicillin-resistant Staphylococcus aureus PH217, Ampicillin-resistant Coagulase-negative Staphylococcus aureus, multidrug-resistant (MDR) Enterococcus faecalis PH007R) and two Gram-negative bacteria (multidrug-resistant Escherichia coli, and Salmonella enterica serovar Typhi), compared to the quality control strains from ATCC (S. aureus 29213, E. faecalis 25922, E. coli 29212) and MTCC (S. Typhi 734). Two of the four Schiff bases 1a and 1b are found to be more active than their counterpart 1c and 1d; while 1a have showed significant activity by inhibiting MRSA PH217 and MDR isolates of E. coli at the minimum inhibitory concentration (MIC) of 150μg/mL and 128μg/mL with MBC of 1024µg/mL, respectively. On the other hand, the MIC of 1b was 150μg/mL against both S. aureus ATCC 29213 and Salmonella Typhi MTCC 734, compared to the control antibiotics Ampicillin and Gentamycin. Scanning electron microscopy demonstrated the altered surface structure of bacterial cells as a possible mechanism of action, supported by the in-silico molecular docking analysis.

The impact of COVID-19 on microbiological profile and antibiotic consumption in ICU: a retrospective study in an infectious disease hospital in Brazil

BackgroundThe COVID-19 pandemic has triggered crises in the public health sector that have complex and multifaceted interrelationships with antimicrobial resistance. It is important to evaluate the impact of COVID-19 on microbiological profile, antibiotic and alcohol gel consumption in Intensive Care Units (ICU). MethodsThis is a retrospective study undertaken in an infectious disease hospital located in Bahia/Brazil during three periods: from March 2019 to February 2020; from March 2020 to February 2021; and from March 2021 to February 2022. It was evaluated the incidence density of Candida spp and of multidrug-resistant Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species (ESKAPE group) in blood, urine and tracheal secretion isolated 48 h after the patient's admission to the ICU, as well as the use of alcohol gel (in milliliters) and consumption of antibiotics in Defined Daily Dose (DDD) per 1,000 ICU patient-days in the previous year and in the first two years of COVID-19 pandemic. ResultsThere was an increase in Candida spp. (5.81, p < 0.001, IRR = 10.47, 95 % CI 2.57‒42.62) and in carbapenem-resistant A. baumannii in clinical cultures (4.71, p < 0.001, IRR = 8.46, 95 % CI 2.07‒34.60), the latter mainly in tracheal secretions (3.18, p= 0.02, IRR = 11.47, 95 % CI 1.58‒83.39). A rise in the consumption of ceftriaxone and piperacillin-tazobactam, along with an increase in the utilization of alcohol gel were observed. ConclusionThe shifting microbiological profile can be attributed to both the unique characteristics of patients with COVID-19 and the adjustments made to healthcare facilities' structural and work routines. Understanding these changes is essential in addressing the accelerated impact of antimicrobial resistance during the pandemic. Therefore, conducting thorough reviews of institutional practices and routines becomes critical in mitigating the consequences of antimicrobial resistance and its implications for patient care.

Comparative Study on the Antimicrobial Activities and Metabolic Profiles of Five Usnea Species from the Philippines.

The rapid emergence of resistant bacteria is occurring worldwide, endangering the efficacy of antibiotics. Hence, there is a need to search for new sources of antibiotics that either exhibit novel structures or express a new mechanism of action. The lichen Usnea, with its wide range of unique, biologically potent secondary metabolites, may solve this problem. In this study, Usnea species were collected in the Northern Philippines, identified through combined morphological and biochemical characterization, and tested for antimicrobial activities against the multidrug-resistant ESKAPE pathogens, i.e., Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter cloacae, two standard antibiotic-sensitive test bacteria, and a yeast. A total of 46 lichen specimens were collected and later identified as Usnea baileyi (10), U. diffracta (10), U. glabrata (12), U. longissima (4), and U. rubicunda (10). The results show that the crude extracts of the Usnea species exhibited promising in vitro inhibitory activities against standard antibiotic-sensitive (E. faecalis ATCC 29212) and multidrug-resistant (methicillin-resistant S. aureus and E. faecalis) Gram-positive bacteria. Additionally, lichen compounds of representative specimens per species were identified and profiled using thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). The detection of lichen acids (LA) via HPLC showed the presence of 24 peaks of lichen acids. TLC-bioautography identified the bioactive lichen acids as alectronic acid, connorstictic acid, consalazinic acid, diffractaic acid, echinocarpic acid, erythrin acid, galbinic acid, hypoconstictic acid, hyposalazinic acid, hypostictic acid, lobaric acid, menegazzaic acid, micareic acid, pannarin, salazinic acid, stictic acid, and usnic acid. Our study highlighted the wide spectrum of opportunities for using lichens for the discovery of potential antimicrobial agents.

Important Features for Protein Foldings in Two Acyl Carrier Proteins from Enterococcus faecalis.

The emergence of multi-drug resistant Enterococcus faecalis raises a serious threat to global public health. E. faecalis is a gram-positive intestinal commensal bacterium found in humans. E. faecalis can endure extreme environments such as high temperature, pressure, and high salt, which facilitates them to cause infection in hospitals. E. faecalis has two acyl carrier proteins, AcpA (EfAcpA) in de novo fatty acid synthesis (FAS) and AcpB (EfAcpB) which utilizes exogenous fatty acids. Previously, we determined the tertiary structures of these two ACPs and investigated their structure-function relationships. Solution structures revealed that overall folding of these two ACPs is similar to those of other bacterial ACPs. However, circular dichroism (CD) experiments showed that the melting temperature of EfAcpA is 76.3°C and that of EfAcpB is 79.2°C, which are much higher than those of other bacterial ACPs. In this study, to understand the origin of their structural stabilities, we verified the important residues for stable folding of these two ACPs by monitoring thermal and chemical denaturation. Hydrogen/deuterium exchange and chemical denaturation experiments on wild-type and mutant proteins revealed that Ile10 of EfAcpA and Ile14 of EfAcpB mediate compact intramolecular packing and promote high thermostability and stable folding. E. faecalis may maximize efficiency of FAS and increase adaptability to the environmental stress by having two thermostable ACPs. This study may provide insight into bacterial adaptability and development of antibiotics against multi-drug-resistant E. faecalis.

Potential of phage EF-N13 as an alternative treatment strategy for mastitis infections caused by multidrug-resistant Enterococcus faecalis

Bovine mastitis is the most common and costly disease affecting dairy cattle throughout the world. Enterococcus faecalis is one of the environmental origin mastitis-causing pathogens. The treatment of bovine mastitis is primarily based on antibiotics. Due to the negative impact of developing antibiotic resistance and adverse effects on soil and water environments, the trend toward use of nonantibiotic treatments is increasing. Phages may represent a promising alternative treatment strategy. However, it is unknown whether phages have therapeutic effects on E. faecalis-induced mastitis. Thus, the objective of this study was to investigate the degree of protection conferred by a phage during murine mastitis caused by multidrug-resistant E. faecalis. Enterococcus faecalis was isolated from the milk of dairy cows with mastitis, and a phage was isolated using the E. faecalis isolates as hosts. The bactericidal ability of the phage against E. faecalis and the ability to prevent biofilm formation were determined in vitro. The therapeutic potential of the phage on murine mastitis was evaluated in vivo. We isolated 14 strains of E. faecalis from the milk of cows with mastitis, all of which exhibited multidrug resistance, and most (10/14) could form strong biofilms. Subsequently, a new phage (EF-N13) was isolated using the multidrug-resistant E. faecalis N13 (isolated from mastitic milk) as the host. The phage EF-N13 belongs to the family Myoviridae, which has short latent periods (5 min) and high bursts (284 pfu/cell). The genome of EF-N13 lacked bacterial virulence-, antibiotic resistance-, and lysogenesis-related genes. Furthermore, bacterial loading in the raw milk medium was significantly reduced by EF-N13 and was unaffected by potential IgG antibodies. In fact, EF-N13 could effectively prevent the formation of biofilm by multidrug-resistant E. faecalis. All of these characteristics suggest that EF-N13 has potential as mastitis therapy. In vivo, 1 × 105 cfu/gland of multidrug-resistant E. faecalis N13 resulted in mastitis development within 24 h. A single dose of phage EF-N13 (1 × 104, 1 × 105, or 1 × 106 pfu/gland) could significantly decrease bacterial counts in the mammary gland at 24 h postinfection. Histopathological observations demonstrated that treatment with phage EF-N13 effectively alleviated mammary gland inflammation and damage. This effect was confirmed by the lower levels of proinflammatory cytokines IL-6, IL-1β, and tumor necrosis factor-α in the mammary gland treated with phage EF-N13 compared with those treated with phosphate-buffered saline. Overall, the data underscored the potential of phage EF-N13 as an alternative therapy for bovine mastitis caused by multidrug-resistant E. faecalis.

Genetic characterization of MDR genomic elements carrying two aac(6')-aph(2″) genes in feline-derived clinical Enterococcus faecalis isolate.

Multidrug-resistant Enterococcus faecalis (E. faecalis) often cause intestinal infections in cats. The aim of this study was to investigate a multidrug-resistant E. faecalis isolate for plasmidic and chromosomal antimicrobial resistance and their genetic environment. E. faecalis strain ESC1 was obtained from the feces of a cat. Antimicrobial susceptibility testing was carried out using the broth microdilution method. Conjugation experiments were performed using Escherichia coli and Staphylococcus aureus as receptors. Complete sequences of chromosomal DNA and plasmids were generated by whole genome sequencing (WGS) and bioinformatics analysis for the presence of drug resistance genes and mobile elements. Multidrug-resistant E. faecalis ESC1 contained a chromosome and three plasmids. The amino acid at position 80 of the parC gene on the chromosome was mutated from serine to isoleucine, and hence the amino acid mutation at this site led to the resistance of ESC1 strain to fluoroquinolones. Eleven antibiotic resistance genes were located on two plasmids. We identified a novel composite transposon carrying two aminoglycoside resistance genes aac(6')-aph(2″). This study reported the coexistence of a novel 5.4 kb composite transposon and a resistance plasmid with multiple homologous recombination in an isolate of E. faecalis ESC1. This data provides a basis for understanding the genomic signature and antimicrobial resistance mechanisms of this pathogen.

In vitro antibacterial efficacy of autologous conditioned plasma and amniotic membrane eye drops.

To determine the in vitro antibacterial efficacy of equine and canine autologous conditioned plasma (ACP) and amniotic membrane extract eye drops (AMEED) against aerobic bacteria common to the corneal surface. Canine (n = 4) and equine (n = 4) anticoagulated whole blood samples were sterilely collected, pooled for each species, and processed using the Arthrex ACP® Double-Syringe System. Platelet counts were performed on ACP and pooled blood. AMEED were obtained from a commercial source. An electronic medical records search (2013-2022) identified aerobic bacteria cultured from canine and equine corneal ulcers at Mississippi State University College of Veterinary Medicine (MSU-CVM). Ten commonly isolated bacteria for each species were collected from cultures submitted to the MSU-CVM Microbiology Diagnostic Service and frozen at -80°C. The Kirby-Bauer disk diffusion method was used to determine the sensitivities of these isolates to ACP and AMEED. Bacterial isolates were plated onto Mueller-Hinton +5% sheep blood agar and blank sterile discs saturated with 20 μL of ACP or AMEED were tested in duplicate. Imipenem discs served as positive controls and blank discs as negative controls. Zones of inhibition were measured at 18 h. ACP platelet counts were 1.06 and 1.65 times higher than blood for equine and canine samples, respectively. Growth of a multi-drug resistant Enterococcus faecalis was partially inhibited by canine and equine ACP. AMEED did not inhibit growth of any examined bacteria. Canine and equine ACP partially inhibited E. faecalis growth in vitro. Further studies using varying concentrations of ACP against bacterial isolates from corneal ulcers are warranted.

A natural product noraucupatin against multidrug-resistant Enterococcus faecium: an inhibition mechanism study

Background: This work elucidates the antimicrobial activity and mechanism of action of the natural product noraucupatin against MDR Enterococcus faecium. E. faecium has become a major opportunistic pathogen with the worldwide spread of multidrug-resistant (MDR) isolates, especially vancomycin-resistant enterococci (VRE), belongs to “ESKAPE” organisms causing significant problems widely. Hence, there is a pressing need to discover new promising drugs or alternative therapies. Fortunately, we found a natural product noraucupatin (C13H12O3, a biphenyl compound) with “extremely encouraging” anti-clinical drug-resistant bacterial activity isolated from yeast-induced Rowan suspension cells. A comprehensive and in-depth exploration of antimicrobial mechanisms will bring fresh insights for researchers to develop novel antimicrobial strategies against MDR bacteria.Methods: The antibacterial effect of noraucupatin against MDR E. faecium is investigated from a microbial metabolism perspective using microcalorimetry. The antibacterial effect is determined based on the thermodynamic parameters. Based on spectroscopic techniques, microscopy techniques and confocal scanning laser microscopy with membrane probes, the antibacterial mechanism is elucidated definitely.Results: Comparing with the IC50 of noraucupatin against MDR Enterococcus faecalis, MRSA, CRPA, the IC50 of noraucupatin against MDR E. faecium was just 67.54 μM. The growth rate of MDR E. faecium decreases with the increase of concentration of noraucupatin. The bacterial intracellular structure entirely collapses and the slurries flow out under the influence of high levels of noraucupatin by TEM. The changes of membrane potential, permeability and evidences of nucleic acid leakage was obtained by CSLM and UV, the mechanism of noraucupatin against MDR E. faecium we explored.Conclusion: The present study highlights the excellent antibacterial activity of noraucupatin against MDR E. faecium by altering the permeability of the membrane and disrupting the membrane potential leading to electrolyte permeation. In addition, noraucupatin has excellent biocompatibility through its haemolytic activity in rabbit erythrocyte. These findings suggest that noraucupatin could be used in infectious diseases caused by MDR E. faecium.

Draft Genome Sequence of Rhizobium sp. Strain AG207R, a Potential Bacteriocin Producer Isolated from Ginger Roots and Exhibiting Broad-Spectrum Antimicrobial Activity, Including against Multidrug-Resistant Enterococcus faecalis.

Here, we report the genome sequence of Rhizobium sp. strain AG207R, isolated from ginger roots. The genome assembly comprises a 6,915,576-bp circular chromosome with 59.56% GC content and possesses 11 regions of biosynthetic gene clusters of secondary metabolites, including one related to bacteriocin.

The LiaFSR-LiaX System Mediates Resistance of Enterococcus faecium to Peptide Antibiotics and to Aureocin A53- and Enterocin L50-Like Bacteriocins.

Multidrug-resistant Enterococcus faecium strains are currently a leading cause of difficult-to-treat nosocomial infections. The emerging resistance of enterococci to last-resort antibiotics, such as daptomycin, prompts a search for alternative antimicrobials. Aureocin A53- and enterocin L50-like bacteriocins are potent antimicrobial agents that form daptomycin-like cationic complexes and have a similar cell envelope-targeting mechanism of action, suggesting their potential as next-generation antibiotics. However, to ensure their safe use, the mechanisms of resistance to these bacteriocins and cross-resistance to antibiotics need to be well understood. Here, we investigated the genetic basis of E. faecium's resistance to aureocin A53- and enterocin L50-like bacteriocins and compared it with that to antibiotics. First, we selected spontaneous mutants resistant to the bacteriocin BHT-B and identified adaptive mutations in the liaFSR-liaX genes encoding the LiaFSR stress response regulatory system and the daptomycin-sensing protein LiaX, respectively. We then demonstrated that a gain-of-function mutation in liaR increases the expression of liaFSR, liaXYZ, cell wall remodeling-associated genes, and hypothetical genes involved in protection against various antimicrobials. Finally, we showed that adaptive mutations or overexpression of liaSR or liaR alone results in cross-resistance to other aureocin A53- and enterocin L50-like bacteriocins, as well as antibiotics targeting specific components of the cell envelope (daptomycin, ramoplanin, gramicidin) or ribosomes (kanamycin and gentamicin). Based on the obtained results, we concluded that activation of the LiaFSR-mediated stress response confers resistance to peptide antibiotics and bacteriocins via a cascade of reactions, eventually leading to cell envelope remodeling. IMPORTANCE Pathogenic enterococci carry virulence factors and a considerable resistome, which makes them one of the most serious and steadily increasing causes of hospital epidemiological risks. Accordingly, Enterococcus faecium is classified into a top-priority ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) group of six highly virulent and multidrug-resistant (MDR) bacterial pathogens for which novel antimicrobial agents need to be developed urgently. Alternative measures, such as the use of bacteriocins, separately or in combination with other antimicrobial agents (e.g., antibiotics), could be a potential solution, especially since several international health agencies recommend and support the development of such interventions. Nevertheless, in order to exploit their efficacy, more basic research on the mechanisms of cell killing and the development of resistance to bacteriocins is needed. The present study fills some of the knowledge gaps regarding the genetic basis of the development of resistance to potent antienterococcal bacteriocins, pointing out the common and divergent features regarding the cross-resistance to antibiotics.

Enzymatic synthesis of new antimicrobial peptides for food purposes.

Growing consumer awareness of the potential negative health effects of synthetic antibiotics has prompted the search for more natural preservatives that can improve the safety and quality of food. In this study we report the enzymatic synthesis of N-α-[Carbobenzyloxy]-Ile-Gln (Z-IQ) which is the precursor of Ile-Gln (IQ), a new antibacterial dipeptide, using an aqueous-organic biphasic system formed by 50% (v/v) ethyl acetate in 0.1 M Tris - HCl buffer pH 8. A partially purified proteolytic extract from the fruits of Solanum granuloso leprosum, named granulosain, proved to be a robust biocatalyst for the synthesis of Z-IQ, eliciting 71 ± 0.10% maximal peptide yield in the above described conditions. After cleaving and purifying IQ dipeptide, antimicrobial activity was assayed against Staphylococcus aureus ATCC 25923, Staphylococcus hominis A17771, and Staphylococcus aureus C00195, and MIC values between 118 ± 0.01 μg/mL and 133.7 ± 0.05 μg/mL were obtained. In addition, IQ showed MIC of 82.4 ± 0.01 μg/mL and 85.0 ± 0.00 μg/mL against Escherichia coli ATCC 25922 and Escherichia coli A17683, respectively. IQ did not show inhibitory activity against single-drug resistance (SDR) strains, such as Klebsiella oxytoca A19438 (SDR) and Pseudomonas aeruginosa C00213 (SDR), and against multidrug-resistant Enterococcus faecalis I00125 (MDR). IQ also caused growth inhibition of Helicobacter pylori NCTC 11638 and three wild-type H. pylori strains, which are sensitive to AML, MTZ, LEV and CLA (H. pylori 659), resistant to LEV (H. pylori 661 SDR), and resistant to MTZ (H. pylori 662 SDR). Finally, this study contributes with a new dipeptide (IQ) that can be used as an antimicrobial agent for food preservation or as a safe ingredient of functional foods.

Isolation and phenotypic characterization of bacteriophage SA14 with lytic- and anti-biofilm activity against multidrug-resistant Enterococcus faecalis

BackgroundAntimicrobial resistance is a growing global health concern demanding more attention and action at the international-, national- and regional levels. In the present study, bacteriophage was sought as a potential alternative to traditional antibiotics.ResultsVancomycin-resistant Enterococcus faecalis was isolated from a urine sample. Partial 16S rRNA-gene sequencing and VITEK®2 system were employed for its identification, biochemical characterization, and antibiotic susceptibility testing. The isolate was resistant to eight antibiotics (out of 11): vancomycin, gentamicin (high-level synergy), streptomycin (high-level synergy), ciprofloxacin, levofloxacin, erythromycin, quinupristin/dalfopristin, and tetracycline. Bacteriophage SA14 was isolated from sewage water using the multidrug-resistant isolate as a host. Transmission electron micrographs revealed that phage SA14 is a member of the Siphoviridae family displaying the typical circular head and long non-contractile tail. The phage showed characteristic stability to a wide range of solution pH and temperatures, with optimal stability at pH 7.4 and 4 °C, while showing high specificity toward their host. Based on the one-step growth curve, the phage's latent period was 25 min, and the burst size was 20 PFU/ml. The lytic activity of phage SA14 was evaluated at various multiplicities of infection (MOI), all considerably suppressed the growth of the host organism. Moreover, phage SA14 displayed a characteristic anti-biofilm activity as observed by the reduction in adhered biomass and -viable cells in the pre-formed biofilm by 19.1-fold and 2.5-fold, respectively.ConclusionPhage therapy can be a valuable alternative to antibiotics against multi-drug resistant microorganisms.

Multidrug Resistant Enterococcus Faecalis isolated from Root Canals and Its Relationship with The Presence of Some Virulence Genes

Multidrug Resistant Enterococcus Faecalis isolated from Root Canals and Its Relationship with The Presence of Some Virulence Genes

Molecular characterization of potentially virulent multidrug-resistant Enterococcus faecalis isolated from acquired urinary tract infections in Egyptian patients

In this study, 154 urine samples were collected from urinary tract infections (UTIs) of hospitalized patients, with 43 (28%) positive for the presence of Enterococcus faecalis without detection of Enterococcus faecium. Based on the demographic data associated with UTI patients, the prevalence of E. faecalis among females was higher than among males in the age group ?41 years; cases from rural areas showed higher infection than from urban localities. Patients not treated with antibiotics were 2.8-fold more likely to be infected with E. faecalis than patients who received antibiotics. At the molecular level, the genes encoding the virulence determinants in E. faecalis, including cytolysins (cylA, cylB and cylM), gelatinase (gelE), E. faecalis antigen A (efaA), extracellular surface protein (esp), aggregation substance (asa) and collagen binding adhesion (ace) were determined using SYBR green real-time PCR. Antibiotic susceptibility testing showed that almost all strains were multidrug-resistant, with an average multiple antibiotic resistance (MAR) index of 0.55. The colorimetric microtiter plate assay showed that 56% of the strains were biofilm producers. A significant correlation was observed between strong biofilm formation and the presence of cylB and cylM genes. Multidrug-resistant E. faecalis and its virulence potential and biofilm formation ability pose a risk to UTI patients.

Dairy Products: A Potential Source of Multidrug-Resistant Enterococcus faecalis and Enterococcus faecium Strains.

This study attempts to present the antimicrobial resistance, virulence and resistance genes of Enterococcus faecalis and Enterococcus faecium isolated from raw goat's and sheep's milk and cheese. Strains were identified by PCR. The dominant species was E. faecalis (77.8%) and was most often isolated from raw goat's milk. The percentage of antimicrobial-resistant E. faecalis isolates was higher than that of E. faecium isolates, the former most frequently resistant to lincomycin (98%), tetracycline (63%) and streptomycin (16%). Fourteen (22.3%) E. faecalis and 2 (11.1%) E. faecium isolates were identified as multidrug-resistant (MDR). All MDR E. faecalis strains also had virulence genes, whereas one of the two E. faecium strains had them. The most prevalent virulence genes in E. faecalis isolates were asa1 (69.8%) and gelE (57.1%). The most prevalent resistance genes found in both bacterial species were tet(M) (43.2%) and vgaA (22.2%). Enterococci from dairy products are confirmed to be a potential source of the spread of antimicrobial resistance, MDR strains, and virulence and resistance genes. This study highlights several aspects of the virulence and pathogenicity of E. faecalis and E. faecium isolated from dairy products-aspects which are indications for their ongoing monitoring.

Multidrug-resistant Enterococcus faecalis native valve endocarditis – a case report

Enterococcal bacteraemia is often complicated by endocarditis. Treatment for multi-drug resistant (MDR) Enterococcus faecalis infective endocarditis included ampicillin-daptomycin combination or linezolid monotherapy for 8 weeks. Mortality is influenced by appropriateness of antibiotic therapy, comorbidities and antimicrobial resistance.