Strain ATCC Research Articles

In vitro biological activities of Combretum molle R.Br. ex G. Don (Combretaceae) against mastitis-causing organisms

Bovine mastitis, caused mostly by Staphylococcus species, has gained global importance owing to the increasing prevalence of multi-drug resistant bacteria, which comprise a risk to food security and public health. In this study, the antibacterial, anti-biofilm and quorum quenching activities of six leaf extracts of Combretum molle R.Br. ex G. Don prepared using different solvents were assessed against clinical isolates of Staphylococcus aureus and two Staphylococcus ATCC strains (S. aureus ATCC 29213 and S. epidermidis ATCC 35984). The antioxidant and anti-inflammatory activity and cytotoxicity of the extracts was also evaluated. The antibacterial and anti-biofilm potential of the extracts was determined via serial microdilution and crystal violet and INT assays. Quorum quenching activity was ascertained via inhibition of violacein production in Chromobacterium violaceum ATCC 12472. The antioxidant activity was determined using in vitro chemical assays. The 15-lipoxygenase enzyme inhibition and the nitric oxide inhibition assays were utilized to ascertain the anti-inflammatory activity of the extracts. The tetrazolium-based colorimetric (MTT) reduction assay was used to determine the cytotoxicity of the extracts against Vero African green monkey kidney cells. The antibacterial activity of the extracts was moderate to good, with minimum inhibitory concentration (MIC) values of 0.02–0.63 mg/mL. The extracts had promising biofilm inhibition (≥50 %) against four of the test strains. The effects of the extracts on the metabolic activity of the test strains showed ≥ 50 % inhibition in most of the test strains at the different test times. All extracts had moderate to excellent quorum quenching activity at different concentrations with an inhibition ranging between 32.81- 96.32 %. The methanol and cold water extracts had the best antioxidant activity against the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals with IC50 of 7.79 and 2.34 µg/mL, respectively. The hot water extract (AQH) had the best anti-inflammatory activity in terms of 15-lipoxygenase enzyme inhibition with 85.26 % inhibition, while the methanol extract had the best nitric oxide inhibition in LPS-induced RAW 264.7 macrophages with inhibition of 96.75 % at 100 µg/mL. Selectivity index values of the extracts were as high as 50. Combretum molle, therefore, offers promising potential as a source of antibiofilm and anti-quorum sensing agents with the ability to disrupt microbial virulence factors. Additionally, the extract had good antioxidant and anti-inflammatory properties, supporting further research into its use in preventing and treating bovine mastitis.

Isolation and draft genome sequence of Enterobacter asburiae strain i6 amenable to genetic manipulation.

Enterobacter asburiae is a species of Gram-negative bacteria that is found in soil, water, and sewage. E. asburiae is generally considered to be an opportunistic pathogen, but has also been reported as a plant growth-promoting bacterium (PGPB), which may have beneficial effects on plant growth and development. However, genetic analysis of E. asburiae has been limited, possibly due to its redundant enzymes that digest exogenous DNA in the cell. Here, an E. asburiae strain i6 was isolated from soil in Nara, Japan. This strain was amenable to transformation and the one-step gene inactivation method based on λ Red recombinase. The transformation efficiency of the i6 strain with the 10 kb plasmid DNA pCF430 was at least four orders of magnitude higher than that of the previously sequenced E. asburiae strain ATCC 35953, which could not be transformed with the same plasmid DNA. A draft genome sequence of the i6 strain was determined and deposited into the database, allowing several factors that may determine transformation efficiency to be perturbed and tested. Together with the amenability of the i6 strain to genetic manipulation, the information from the i6 genome will facilitate characterization and fine-tuning of the beneficial and detrimental traits of this species.

Modeling the effects of prebiotic interventions on luminal and mucosa-associated gut microbiota without and with Clostridium difficile challenge in vitro.

Prebiotics can modulate the gut microbial community composition and function for improved (gut) health and increase resilience against infections. In vitro models of the gut facilitate the study of intervention effects on the gut microbial community relevant to health. The mucosa-associated gut microbiota, which thrives in close contact with the host plays a pivotal role in colonization resistance and health. Therefore, we here introduce the Mi-screen, an experimental approach implementing a 96-well plate equipped with a mucus agar layer for the additional culturing of mucosa-associated microbiota in vitro. In this study, we screened the effects of 2'-Fucosyllactose (2'-FL), fructooligosaccharides (FOS), and inulin within a complex microbiota without and with infection with the C. difficile strains ATCC 43599 (Ribotype 001) or ATCC BAA-1870 (Ribotype 027). We analyzed the microbial community composition and short-chain fatty acid levels after 48 h of incubation. The inclusion of an additional substrate and surface in the form of the mucus agar layer allowed us to culture a microbial richness ranging between 100-160 in Chao index, with Shannon indices of 5-6 across culture conditions, indicative of a microbial diversity of physiological relevance. The mucus agar layer stimulated the growth of characteristic mucosa-associated bacteria such as Roseburia inulinovorans. The prebiotic interventions affected luminal and mucosal microbial communities cultured in vitro and stimulated short-chain fatty acid production. FOS, inulin and 2'-FL promoted the growth of Bifidobacterium adolescentis within the mucosa-associated microbiota cultured in vitro. When spiking the untreated conditions with pathogenic C. difficile, the strains thrived within the luminal and the mucosal sample types, whereas prebiotic treatments exhibited inhibitory effects on C. difficile growth and prevented colonization. In conclusion, the Mi-screen facilitates the screening of luminal and mucosa-associated gut microbial community dynamics in vitro and therefore fills an important gap in the field of in vitro modeling.

Synergistic antimicrobial nanofiber membranes based on metal incorporated silica nanoparticles as advanced antimicrobial layers.

In this post-new-normal era, the public prioritizes preventive measures over curing, which is a constructive approach to staying healthy. In this study, an innovative antimicrobial membrane material has been developed, showcasing the promising potential for various applications. The metal-doped silica nanoparticles (Ag, Cu, and Co) were incorporated into a cellulose acetate (CA) polymer-based nanofiber membrane using the electrospinning technique. The metal nanoparticles were doped into a silanol network of silica nanoparticles. The fabricated membranes underwent detailed characterization using a wide range of techniques including PXRD, FTIR, Raman, SEM, TEM, TGA, and tensile testing. These analyses provided compelling evidence confirming the successful incorporation of metal-doped silica nanoparticles (Ag, Cu, and Co) into cellulose-based nanofibers. The band gap energies of the fabricated CA mats lie below 3.00 eV, confirming that they are visible light active. The trimetallic silica nanohybrid exhibited the lowest band gap energy of 2.84 eV, proving the self-sterilizing ability of the CA mats. The DPPH assay further confirmed the best radical scavenging activity by the trimetallic silica nanohybrid incorporated nanofiber mat (91.77 ± 0.88%). The antimicrobial activity was assessed by using the bacterial ATCC strains of Staphylococcus aureus, Streptococcus pneumoniae, MRSA (Methicillin-resistant Staphylococcus aureus), Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa and fungal strains; quality control samples of Trichophyton rubrum, Microsporum gypsium, and Aspergillus niger, as well as the ATCC strain of Candida albicans. The trimetallic silica nanohybrid-incorporated CA membranes demonstrated the most significant inhibition zones. The reported findings substantiate the self-sterilizing mat's viability, affordability, efficacy against a broad spectrum of microbial strains, cost-effectiveness, and biodegradability. Furthermore, the mat serves as a dual-purpose physical and biological barrier against microbes, affirming its potential impact.

A capillary-based centrifugal indicator equipped with in situ pathogenic bacteria culture for fast antimicrobial susceptibility testing.

Antimicrobial resistance has become a major global health threat due to the misuse and overuse of antibiotics. Rapid, affordable, and high-efficiency antimicrobial susceptibility testing (AST) is among the effective means to solve this problem. Herein, we developed a capillary-based centrifugal indicator (CBCI) equipped with an in situ culture of pathogenic bacteria for fast AST. The bacterial incubation and growth were performed by macro-incubation, which seamlessly integrated the capillary indicator. Through simple centrifugation, all the bacterial cells were confined at the nanoliter-level capillary column. The packed capillary column height could linearly reflect the bacterial count, and the minimum inhibitory concentration (MIC) was determined based on the difference in the column height between the drug-added groups and the control group. The AST results could easily be determined by the naked eye or smartphone imaging. Thus, the CBCI realized the combination of macro-bacterial incubation and early micro assessment, which accelerated the phenotypic AST without complex microscopic counting or fluorescent labelling. The whole operation process was simple and easy to use. AST results could be determined for E. coli ATCC strains within 3.5 h, and the output results for clinical samples were consistent with the hospital reports. We expect this AST platform to become a useful tool in limiting antimicrobial resistance, especially in remote/resource-limited areas or in underdeveloped countries.

Investigation of phytochemical composition and bioactivity evaluation of extracts from Myrsine umbellata Mart.

The objective of the study was to carry out phytochemical prospection through colorimetric tests to determine the groups of secondary metabolites and also to determine the total content of phenolic compounds (TPC) present in plant extracts methanol (ME), ethyl acetate (EAE), hexane (HE) and dichloromethane (DE) from the leaves of Myrsine umbellata, as well as to investigate the antimicrobial activity against twelve standard ATCC strains by the broth microdilution technique; the antioxidant potential by the DPPH method and the ABTS method and the antibiofilm potential on the biofilm biomass of standard bacteria by the crystal violet technique and tetrazolium salt reduction (MTT) assay. Phytochemical prospection detected the presence of saponins, steroids, alkaloids, anthocyanins, anthocyanidins, flavonoids, and tannins. The results of the quantitative phytochemical estimation revealed a higher content of total phenolics in DE (280.24 ± 0.037 µM GAE g ext. -1) followed by ME (159.01 ± 0.031 µM GAE g ext. -1). The ME showed the best biological activities when compared to the other extracts tested. We observed antimicrobial activity against Gram-positive Staphylococcus epidermidis strain (MIC 3.12 and MBC 6.25), antioxidant percentage of 92.58% against the DPPH radical and 420.31 µM Trolox g ext. -1 against the ABTS radical, finally showed antibiofilm action against Gram-positive strain Staphylococcus aureus, with eradication of the biomass in 92.58%. The results suggest that EM from M. umbellata represents an alternative source of plant bioactives for the development of natura products.

Antimicrobial Activity of African Walnut (<em>Tetracarpidium conophorum</em>) Oil against Bacterial and Fungal Species Causing Food Spoilage and Food Poisoning Diseases

This study evaluated the antibacterial and antifungal activity of African walnut (Tetracarpidium conophorum) oil against species causing food poisoning and food spoilage. African walnut oil was extracted using the solvent extraction method. The fatty acid profile of the oil was determined using gas chromatography mass spectrometry (GC-MS). The agar disc diffusion method was used to determine the antibacterial activity of the oil before using it for further tests. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were also determined using the disc diffusion assay. The result indicates that palmitic (1.53%), linoleic (13.5%), linolenic 80.59%, stearic (4.41%), and eicosenoic acid (0.42%) were present in the oil with higher polyunsaturated fatty acid values. African walnut oil showed remarkable activity against all the Gram positive organisms (Bacillus cereus ATCC 33018, Staphylococcus aureus ATCC 25923, Clostridium perfringes NCTC 8799, and Listeria monocytogenes ATCC 13932) with the inhibition zones ranging from 21.6 ± 0.27 mm to 26.3 ± 0.23 while the Gram negative organisms (Pseudomonas fluorescens ATCC 13883, Pseudomonas fragi ATCC 4973, Escherichia coli ATCC 12806, Salmonella enterica subsp. enterica serovar Typhimurium strain ATCC 14028) were less sensitive and resistant to the oil chromatography-mass with inhibition zones ranging from 6.3 ± 0.31 to 9.9 ± 0.21 mm. Out of the tested oil concentrations from 100 – 0.39 mg/mL, MIC obtained for the Gram positive organisms was 1.56 mg/mL while it was 3.13 mg/mL for Gram negative bacteria (except L. monocytogenes). The antifungal test reveals the MIC range of 100 - 0.78 mg/mL in all the fungal isolates tested. African walnut oil has proved to be potentially active against the Gram positive bacterial and fungal species tested indicating that it can be used as a natural alternative to control food spoilage and food poisoning diseases.

Preventive Action of Blue Lotus (Nymphaea Caerulea) Flower Extract against E. Coli-Induced Immune-Pathological Changes In Gallus gallus domesticus Embryo.

Nymphaea caerulea is an aquatic plant originally found in the Nile River has several therapeutic activities - anti-depressant, anti-inflammatory, anti-oxidant, and anti-microbial activities. This led us to perform the study focusing on the anti-microbial properties of the flower extract. Crude ethanolic extract of petals and pollens of N. caerulea flower were prepared and its antimicrobial activity was checked against E. coli. The Minimum Inhibition Concentration value was determined showing that both the extracts had similar capability against both the strains, with MIC value of 0.39mg/ml and 0.78mg/ml MIC against E.coli ATCC and MDR strains respectively. Further studies were done to study the gross morphological changes and the genetic expression changes of IL-10 and IFN-γ in E. coli-infected Gallus gallus domesticus embryo models. From the results, it can be said that the extract has preventive effects that reduce haemorrhages of the embryos when infected with E. coli. Moreover, there was slight increase in the level of IL-10 cytokine gene expression indicating its anti-inflammatory action along with a higher increase in the IFN-γ cytokine gene expressions responsible for activating the host immunity. Thus, the findings indicate the probable potential role of N. caerulea flower extract to act as an antibacterial agent.

Influence of genomic variations on glanders serodiagnostic antigens using integrative genomic and transcriptomic approaches.

Glanders is a highly contagious and life-threatening zoonotic disease caused by Burkholderia mallei (B. mallei). Without an effective vaccine or treatment, early diagnosis has been regarded as the most effective method to prevent glanders transmission. Currently, the diagnosis of glanders is heavily reliant on serological tests. However, given that markedly different host immune responses can be elicited by genetically different strains of the same bacterial species, infection by B. mallei, whose genome is unstable and plastic, may result in various immune responses. This variability can make the serodiagnosis of glanders challenging. Therefore, there is a need for a comprehensive understanding and assessment of how B. mallei genomic variations impact the appropriateness of specific target antigens for glanders serodiagnosis. In this study, we investigated how genomic variations in the B. mallei genome affect gene content (gene presence/absence) and expression, with a special focus on antigens used or potentially used in serodiagnosis. In all the genome sequences of B. mallei isolates available in NCBI's RefSeq database (accessed in July 2023) and in-house sequenced samples, extensive small and large variations were observed when compared to the type strain ATCC 23344. Further pan-genome analysis of those assemblies revealed variations of gene content among all available genomes of B. mallei. Specifically, differences in gene content ranging from 31 to 715 genes with an average of 334 gene presence-absence variations were found in strains with complete or chromosome-level genome assemblies, using the ATCC 23344 strain as a reference. The affected genes included some encoded proteins used as serodiagnostic antigens, which were lost due mainly to structural variations. Additionally, a transcriptomic analysis was performed using the type strain ATCC 23344 and strain Zagreb which has been widely utilized to produce glanders antigens. In total, 388 significant differentially expressed genes were identified between these two strains, including genes related to bacterial pathogenesis and virulence, some of which were associated with genomic variations, particularly structural variations. To our knowledge, this is the first comprehensive study to uncover the impacts of genetic variations of B. mallei on its gene content and expression. These differences would have significant impacts on host innate and adaptive immunity, including antibody production, during infection. This study provides novel insights into B. mallei genetic variants, knowledge which will help to improve glanders serodiagnosis.

Understanding the diagnosis of catheter-related bloodstream infection: real-time monitoring of biofilm growth dynamics using time-lapse optical microscopy.

The differential time to positivity (DTTP) technique is recommended for the conservative diagnosis of catheter-related bloodstream infection (C-RBSI). The technique is based on a 120-minute difference between microbial growth in blood drawn through the catheter and blood drawn through a peripheral vein. However, this cut-off has failed to confirm C-RBSI caused by Candida spp. and Staphylococcus aureus. We hypothesized that the biofilm of both microorganisms disperses faster than that of other microorganisms and that microbial load is rapidly equalized between catheter and peripheral blood. Therefore, our aim was to compare the biofilm dynamics of various microorganisms. Biofilm of ATCC strains of methicillin-resistant Staphylococcus epidermidis, methicillin-susceptible S. aureus, Enterococcus faecalis, Escherichia coli and Candida albicans was grown on silicon disks and analyzed using time-lapse optical microscopy. The time-lapse images of biofilms were processed using ImageJ2 software. Cell dispersal time and biofilm thickness were calculated. The mean (standard deviation) dispersal time in C. albicans and S. aureus biofilms was at least nearly 3 hours lower than in biofilm of S. epidermidis, and at least 15 minutes than in E. faecalis and E. coli biofilms. Our findings could explain why early dissemination of cells in C. albicans and S. aureus prevents us from confirming or ruling out the catheter as the source of the bloodstream infection using the cut-off of 120 minutes in the DTTP technique. In addition, DTTP may not be sufficiently reliable for E. coli since their dispersion time is less than the cut-off of 120 minutes.

Genome characterization and taxonomy of Actinomyces acetigenes sp. nov., and Actinomyces stomatis sp. nov., previously isolated from the human oral cavity

BackgroundActinomyces strains are commonly found as part of the normal microflora on human tissue surfaces, including the oropharynx, gastrointestinal tract, and female genital tract. Understanding the diversity and characterization of Actinomyces species is crucial for human health, as they play an important role in dental plaque formation and biofilm-related infections. Two Actinomyces strains ATCC 49340 T and ATCC 51655 T have been utilized in various studies, but their accurate species classification and description remain unresolved.ResultsTo investigate the genomic properties and taxonomic status of these strains, we employed both 16S rRNA Sanger sequencing and whole-genome sequencing using the Illumina HiSeq X Ten platform with PE151 (paired-end) sequencing. Our analyses revealed that the draft genome of Actinomyces acetigenes ATCC 49340 T was 3.27 Mbp with a 68.0% GC content, and Actinomyces stomatis ATCC 51655 T has a genome size of 3.08 Mbp with a 68.1% GC content. Multi-locus (atpA, rpoB, pgi, metG, gltA, gyrA, and core genome SNPs) sequence analysis supported the phylogenetic placement of strains ATCC 51655 T and ATCC 49340 T as independent lineages. Digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), and average amino acid identity (AAI) analyses indicated that both strains represented novel Actinomyces species, with values below the threshold for species demarcation (70% dDDH, 95% ANI and AAI). Pangenome analysis identified 5,731 gene clusters with strains ATCC 49340 T and ATCC 51655 T possessing 1,515 and 1,518 unique gene clusters, respectively. Additionally, genomic islands (GIs) prediction uncovered 24 putative GIs in strain ATCC 49340 T and 16 in strain ATCC 51655 T, contributing to their genetic diversity and potential adaptive capabilities. Pathogenicity analysis highlighted the potential human pathogenicity risk associated with both strains, with several virulence-associated factors identified. CRISPR-Cas analysis exposed the presence of CRISPR and Cas genes in both strains, indicating these strains might evolve a robust defense mechanism against them.ConclusionThis study supports the classification of strains ATCC 49340 T and ATCC 51655 T as novel species within the Actinomyces, in which the name Actinomyces acetigenes sp. nov. (type strain ATCC 49340 T = VPI D163E-3 T = CCUG 34286 T = CCUG 35339 T) and Actinomyces stomatis sp. nov. (type strain ATCC 51655 T = PK606T = CCUG 33930 T) are proposed.

Draft genome sequence of Xylella fastidiosa strain ATCC 35874 isolated from infected red oak in Washington, DC.

We report here the draft genome sequence of Xylella fastidiosa strain ATCC 35874. The strain was originally isolated from infected red oak in Washington, DC, and obtained from the American Type Culture Collection. The ATCC 35874 genome contains 2,543,332 bp and has a G + C content of 51.72%.

Safety of oil from Schizochytrium sp. (strain CABIO-A-2) for use in infant and follow-on formula as a novel food pursuant to Regulation (EU) 2015/2283.

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of Schizochytrium sp. (strain CABIO-A-2) oil as a novel food (NF) pursuant to Regulation (EU) 2015/2283. S. sp. is a single-cell microalga. The NF is a mixture of triglycerides in which docosahexaenoic acid (DHA) represents 38%-44% of fatty acids. The applicant proposed to use the NF in infant formulae (IF) and follow-on formulae (FOF). The use levels proposed by the applicant were derived from Regulation (EU) 2016/127, which states the mandatory addition of DHA to IF and FOF at the level of 20-50 mg/100 kcal. The evidence provided demonstrated that the strain S. sp. CABIO-A-2 is phylogenetically closely related to the strain S. sp. ATCC 20888. The assessment of some already authorised S. sp. oils in the Union list were also based on similarities with the strain ATCC 20888. The applicant provided a 90-day repeated dose toxicity study in rats with the NF. No adverse effects were observed up to the highest dose tested, i.e. 10.2 g/kg body weight (bw) per day. Taking into account the toxicity studies performed with the NF and with DHA-oils derived from strains belonging to the genus Schizochytrium, its phylogenetical profile, the production process, the composition of the NF and the absence of marine biotoxins and viable cells in the NF, the Panel considers that there are no concerns with regard to the toxicity of the NF. The Panel concludes that the NF is safe under the proposed conditions of use.

Novel indolinone-tethered benzothiophenes as anti-tubercular agents against MDR/XDR M. tuberculosis: Design, synthesis, biological evaluation and in vivo pharmacokinetic study

Joining the global effort to eradicate tuberculosis, one of the deadliest infectious killers in the world, we disclose in this paper the design and synthesis of new indolinone-tethered benzothiophene hybrids 6a-i and 7a-i as potential anti-tubercular agents. The MICs were determined in vitro for the synthesized compounds against the sensitive M. tuberculosis strain ATCC 25177. Potent compounds 6b, 6d, 6f, 6h, 7a, 7b, 7d, 7f, 7h and 7i were furtherly assessed versus resistant MDR-TB and XDR-TB. Structure activity relationship investigation of the synthesized compounds was illustrated, accordingly. Superlative potency was unveiled for compound 6h (MIC = 0.48, 1.95 and 7.81 µg/mL for ATCC 25177 sensitive TB strain, resistant MDR-TB and XDR-TB, respectively). Moreover, validated in vivo pharmacokinetic study was performed for the most potent derivative 6h revealing superior pharmacokinetic profile over the reference drug. For further exploration of the anti-tubercular mechanism of action, molecular docking was carried out for the former compound in DprE1 active site as one of the important biological targets of TB. The binding mode and the docking score uncovered exceptional binding when compared to the co-crystallized ligand suggesting that it maybe the underlying target for its outstanding anti-tubercular potency.

2809. In Vitro Synergy of Antibiotic Combinations Against Enterococcus gallinarum

Abstract Background Enterococci are an important cause of endocarditis, particularly involving prosthetic valves. The prevalence of E. gallinarum has been increasing in recent years. Unlike E. faecalis, no information is available regarding the bactericidal activity of ampicillin alone or combined with gentamicin or ceftriaxone against E. gallinarum. Methods Ten blood culture isolates of E. gallinarum were studied. The isolates came from unique patients at a single hospital. MICs of ampicillin, ceftriaxone and gentamicin were done by the CLSI microdilution method. ATCC strains E. faecalis 29212 and P. aeruginosa 27853 were used as controls. Time-kill studies were performed in CA-MHB for ampicillin 10 mg/L, ceftriaxone 10 mg/L, gentamicin at 0.25 x MIC up to a maximum of 4 mg/L, ampicillin + ceftriaxone, and ampicillin + gentamicin. Bactericidal activity was defined as a 1,000-fold decrease in the log10 cfu/mL at 24 h. Synergy was defined as a 100-fold decrease in the log10 cfu/ml at 24 h in a combination compared to each single agent. Results The MICs of ampicillin ranged from 1 to 8 mg/L, gentamicin from 2 to 16 mg/L, and ceftriaxone were all ≥ 32 mg/L. Results of the time-kill studies are summarized in the Table. Ampicillin alone was bactericidal against a single isolate. For that isolate, testing of ampicillin at 0.25 x MIC with gentamicin demonstrated synergy. The combination of ampicillin + ceftriaxone was synergistic against a single isolate, but was otherwise similar to ampicillin alone. Ampicillin + gentamicin was bactericidal against all isolates and was synergistic against all but one isolate. Conclusion Ampicillin alone was generally not bactericidal against E. gallinarum but had synergistic bactericidal activity when combined with gentamicin, similar to the findings with E. faecalis. However, unlike E. faecalis, ampicillin + ceftriaxone was not bactericidal against most isolates of E. gallinarum. These findings support the suggestion that ampicillin + gentamicin might be the optimal treatment for endovascular infections caused by E. gallinarum. Disclosures All Authors: No reported disclosures

Chemical Composition and Antimicrobial Activity against the Listeria monocytogenes of Essential Oils from Seven Salvia Species.

In recent years, essential oils (EOs) have received interest due to their antibacterial properties. Accordingly, the present study aimed to investigate the effectiveness of the EOs obtained from seven species of Salvia on three strains of Listeria monocytogenes (two serotyped wild strains and one ATCC strain), a bacterium able to contaminate food products and cause foodborne disease in humans. The Salvia species analysed in the present study were cultivated at the Botanic Garden and Museum of the University of Pisa, and their air-dried aerial parts were subjected to hydrodistillation using a Clevenger apparatus. The obtained EOs were analysed via gas chromatography coupled with mass spectrometry for the evaluation of their chemical composition, and they were tested for their inhibitory and bactericidal activities by means of MIC and MBC. The tested Eos showed promising results, and the best outcomes were reached by S. chamaedryoides EO, showing an MIC of 1:256 and an MBC of 1:64. The predominant compounds of this EO were the sesquiterpenes caryophyllene oxide and β-caryophyllene, together with the monoterpenes bornyl acetate and borneol. These results suggest that these EOs may possibly be used in the food industry as preservatives of natural origins.

New Meroterpenoid Derivatives from the Pomegranate-Derived Endophytic Fungus Talaromyces purpureogenus.

In this study, we report the isolation of two new meroterpenoids, miniolutelide D (1) and miniolutelide E (13-epi-miniolutelide C) (2), along with two meroterpenoidal analogues (3 and 4) and two phenolic compounds (5 and 6) from the endophytic fungus Talaromyces purpureogenus derived from Punica granatum fruits. Their structures were elucidated using extensive MS, 1D, and 2D NMR spectroscopic analyses as well as by comparing with data in the literature. The absolute configurations of 1 and 2 were determined using TDDFT-ECD calculations. Antimicrobial activity was evaluated. Compound 5 displayed significant activity against methicillin-resistant Staphylococcus aureus strain ATCC 700699 and moderate activity against S. aureus strain ATCC 29213.

Coevolutionary phage training andJoint application delays the emergence ofphage resistance inPseudomonas aeruginosa.

Antibiotic-resistant bacteria are current threats to available antibiotic therapies, and this has renewed interest in the therapeutic use of phage as an alternative. However, development of phage resistance has led to unsuccessful therapeutic outcomes. In the current study, we applied phage training to minimize bacterial phage resistance and to improve treatment outcome by adapting the phage to their target hosts during co-evolution. We isolated and characterized a novel Pseudomonas aeruginosa N4-like lytic phage (PWJ) from wastewater in Yangzhou, China. PWJ is a double-stranded DNA podovirus that can efficiently lyse the model strain ATCC 27,853 and opportunistic pathogen PAO1. Genome sequencing of PWJ revealed features similar to those of the N4-like P. aeruginosa phage YH6. We used PWJ to screen for an evolved trained phage (WJ_Ev14) that restored infectivity to PWJ phage bacterial resisters. BLASTN analysis revealed that WJ_Ev14 is identical to its ancestor PWJ except for the amino acid substitution R1051S in its tail fiber protein. Moreover, phage adsorption tests and transmission electron microscopy of resistant bacteria demonstrated that the R1051S substitution was most likely the reason WJ_Ev14 could re-adsorb and regain infectivity. Furthermore, phage therapy assays in vitro and in a mouse P. aeruginosa lung infection model demonstrated that PWJ treatment resulted in improved clinical results and a reduction in lung bacterial load whereas the joint phage cocktail (PWJ+ WJ_Ev14) was better able to delay the emergence of resister bacteria. The phage cocktail (PWJ +WJ_Ev14) represents a promising candidate for inclusion in phage cocktails developed for clinical applications.

Isolation and activity test of antioxidant, antibacterial, and cytotoxic compounds from the stem bark of Aglaia foveolata Pannell

Aglaia foveolata Pannell (A. foveolata) is a type of plant that has many benefits, including the skin, leaves, roots, and seeds as medicinal ingredients. The potential of this plant is inseparable from the content of various bioactive compounds. This study aims to isolate, characterize the active compound from the stem bark of A. foveolata and test its activity as an antioxidant with the ABTS method, cytotoxic (MCF-7 cancer cells) with the MTT method, and antibacterial (bacterial strains ATCC and MDR) with the MIC. There are four isolated compounds obtained, namely (1) 17,24-epoxy-25-hydroxybaccharan-3-one, (2) β-stigmasterol glucoside, (3) Eichlerianic acid, and (4) 17,24-epoxy-25 -hydroxy-3- oxobaccharan-21-oic acid, which is a class of triterpenoid and steroid compounds. The best activity as an antioxidant was compound 3 (25.68 µg/mL); cytotoxic activity against MCF-7 cells namely compound 4 (94.59 µg/mL); antibacterial activity against ATCC strains: (1) P. aeruginosa namely compound 3 (29.4 µg/mL), (2) E. coli, (3) S. aureus, (4) B. subtilis for compounds 1, 2, and 4 have the same activity (62.5 µg/mL) while compound 3 was not active; MDR bacterial strains: (1) P. aeruginosa namely compound 4 (62.5 µg/mL), (2) E. coli namely compound 3 (62.5 µg/mL), (3) S. aureus namely compound 4 (62 .5 µg/mL), (4) B. subtilis namely compound 4 (62.5 µg/mL) and (5) K. pneumoniae namely compound 1 (125 µg/mL).

Silica-based silver nanocomposite 80S/Ag as Aggregatibacter actinomycetemcomitans inhibitor and its in vitro bioactivity

Background/purposeAs a commonly-found pathogen in periodontal disease, Aggregatibacter actinomycetemcomitans has been reported with several antibiotic resistance. Thus, to develop an alternative and protective therapy for A. actinomycetemcomitans infections is urgently needed in dentistry. In this study, we sought to synthesize a silica-based material to deliver silver nanoparticles for antibacterial purposes. Also, the bioactivities were examined via analyzing the formation of hydroxyapatite. Materials and methodsThe 80S/Ag powders were prepared by the evaporation-induced self-assembly method, with Si, Ca, P, and Ag composition ratios of 80, 15, 5, and 1/5/10 (mole percentage), respectively. The nitrogen adsorption-desorption isotherms, transmission electron microscope, selected area electron diffraction, and Fourier transform infrared spectroscopy were conducted for textural analyses. The disk diffusion test was carried out against A. actinomycetemcomitans strain ATCC 29523. In vitro bioactivity assessment involved soaking 80S/Ag membrane powders in acellular simulated body fluid. ResultsWe successfully developed a material consisting of Si, Ca, P, and Ag, namely the 80S/Ag. In the antibacterial testing, the 80S/Ag demonstrated antibacterial activity against the commonly-found oral pathogen, A. actinomycetemcomitans, with a long-lasting effect for 168h. The formation of hydroxyapatite in simulated body fluid highlighted the characteristic of dentine remineralization for the 80S/Ag. The increased pH values after immersion in simulated body fluid would help neutralize the acidic oral environment. ConclusionOur results indicate that 80S/Ag possesses remarkable antibacterial properties, hydroxyapatite formation, and increased pH values after immersion in simulated body fluid, supporting the potential therapeutic application of 80S/Ag for treating periodontal disease.