andEscherichia Coli Research Articles

Emulsion electrospun epigallocatechin gallate-loaded silk fibroin/polycaprolactone nanofibrous membranes for enhancing guided bone regeneration

Guided bone regeneration (GBR) membranes play an important role in oral bone regeneration. However, enhancing their bone regeneration potential and antibacterial properties is crucial. Herein, silk fibroin (SF)/polycaprolactone (PCL) core-shell nanofibers loaded with epigallocatechin gallate (EGCG) were prepared using emulsion electrospinning. The nanofibrous membranes were characterized via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, water contact angle (CA) measurement, mechanical properties testing, drug release kinetics, and 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) free radical scavenging assay. Mouse pre-osteoblast MC3T3-E1 cells were used to assess the biological characteristics, cytocompatibility, and osteogenic differentiation potential of the nanofibrous membrane. Additionally, the antibacterial properties againstStaphylococcus aureus (S. aureus)andEscherichia coli (E. coli)were evaluated. The nanofibers prepared by emulsion electrospinning exhibited a stable core-shell structure with a smooth and continuous surface. The tensile strength of the SF/PCL membrane loaded with EGCG was 3.88 ± 0.15 Mpa, the water CA was 50°, and the DPPH clearance rate at 24 h was 81.73% ± 0.07%. The EGCG release rate of membranes prepared by emulsion electrospinning was reduced by 12% within 72 h compared to that of membranes prepared via traditional electrospinning.In vitroexperiments indicate that the core-shell membranes loaded with EGCG demonstrated good cell compatibility and promoted adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. Furthermore, the EGCG-loaded membranes exhibited inhibitory effects onE. coliandS. aureus. These findings indicate that core-shell nanofibrous membranes encapsulated with EGCG prepared using emulsion electrospinning possess good antioxidant, osteogenic, and antibacterial properties, making them potential candidates for research in GBR materials.

Tailoring zirconia surface topography via femtosecond laser-induced nanoscale features: effects on osteoblast cells and antibacterial properties

The performance and long-term durability of dental implants hinge on the quality of bone integration and their resistance to bacteria. This research aims to introduce a surface modification strategy for zirconia implants utilizing femtosecond laser ablation techniques, exploring their impact on osteoblast cell behavior and bacterial performance, as well as the integral factors influencing the soft tissue quality surrounding dental implants. Ultrafast lasers were employed to craft nanoscale groove geometries on zirconia surfaces, with thorough analyses conducted using x-ray diffraction, scanning electron microscopy, atomic force microscopy, and water contact angle measurements. The study evaluated the response of human fetal osteoblastic cell lines to textured zirconia ceramics by assessing alkaline phosphatase activity, collagen I, and interleukin 1βsecretion over a 7 day period. Additionally, the antibacterial behavior of the textured surfaces was investigated usingFusobacterium nucleatum, a common culprit in infections associated with dental implants. Ciprofloxacin (CIP), a widely used antibacterial antibiotic, was loaded onto zirconia ceramic surfaces. The results of this study unveiled a substantial reduction in bacterial adhesion on textured zirconia surfaces. The fine biocompatibility of these surfaces was confirmed through the MTT assay and observations of cell morphology. Moreover, the human fetal osteoblastic cell line exhibited extensive spreading and secreted elevated levels of collagen I and interleukin 1βin the modified samples. Drug release evaluations demonstrated sustained CIP release through a diffusion mechanism, showcasing excellent antibacterial activity against pathogenic bacteria, includingStreptococcus mutans, Pseudomonas aeruginosa, andEscherichia coli.

Sol-Gel-Derived TiO2 and TiO2/Cu Nanoparticles: Synthesis, Characterization, and Antibacterial Efficacy.

This study reports on the antibacterial efficacy of both the TiO2 and TiO2/Cu nanoparticles prepared through the sol-gel method. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. The SEM and TEM showed the spherical morphology of the nanoparticles, while EDX and XPS confirmed the incorporation of Cu into the TiO2 nanoparticles. The XRD confirmed the formation of the tetragonal anatase phase of TiO2/Cu while the FTIR revealed the functional groups linked to the doped TiO2 nanoparticles. The thermal stability of TiO2/Cu was found to be lower than pure TiO2. Moreover, TiO2 and the doped TiO2 nanoparticles were notably effective against Bacillus subtilis(B. subtilis) andEscherichia coli(E. coli); however, the addition of Cu to TiO2 did not have any effect on the antibacterial activity probably due to the lower weight content in the composites. Interestingly, the antibacterial efficiency was determined to be 90 and 80% against B. subtilis and E. coli, respectively.

Immobilization of Ag-NPs onto cellulose-containing fabrics using O2-plasma

Silver nanocomposites (Ag-NPs/PVP) were synthesized through the reduction of Ag+ using Ethylene glycol (EG) and poly(N-vinylpyrrolidone) (PVP) as a protective agent in an alkaline medium. Characterization involved UV–Vis spectrum, and TEM image, confirming the well spread of the nanoparticles with a particle size of range 5–10 nm. Stability, assessed after three months, revealed a zeta potentialof −17 mV, identicating no agglomeration. . PVP role in decreasing the nanoparticle size was studied, attributed to the protective layer preventing aggregation. . The study enhanced the antibacterial activity of various cellulosic fabrics (cotton, linen, and viscose) by activating their surfaces through O2 plasma pretreatment at atmospheric pressure. Activation immobilized the fabric matrix by the extracting radicals fforming functional groups(C = O, –O–C = O, –COH, –COOH, and CH2–OH). Viscose demonstrated the highest effect. FTIR confirmed the formation of polar groups on the fabric surface. Activated cellulosic fabric was treated with Ag-NPs/PVP colloid solution and antibacterial activity was assessed against Staphylococcus aureus (S. aureus) andEscherichia coli (E. coli). Parameters such as: plasma exposure time, Ag-NPs/PVP concentration, and the pretreatment bath temperature were studied.SEM images and EDX spectra verified the presence of nitrogen and silver elements on the treated substrates surface .

Genome-wide fitness analysis identifies genes required for in vitro growth and macrophage infection by African and global epidemic pathovariants of Salmonella enterica Enteritidis.

Salmonella enterica Enteritidis is the second most common serovar associated with invasive non-typhoidal Salmonella (iNTS) disease in sub-Saharan Africa. Previously, genomic and phylogenetic characterization of S . enterica Enteritidis isolates from the human bloodstream led to the discovery of the Central/Eastern African clade (CEAC) and West African clade, which were distinct from the gastroenteritis-associated global epidemic clade (GEC). The African S . enterica Enteritidis clades have unique genetic signatures that include genomic degradation, novel prophage repertoires and multi-drug resistance, but the molecular basis for the enhanced propensity of African S . enterica Enteritidis to cause bloodstream infection is poorly understood. We used transposon insertion sequencing (TIS) to identify the genetic determinants of the GEC representative strain P125109 and the CEAC representative strain D7795 for growth in three in vitro conditions (LB or minimal NonSPI2 and InSPI2 growth media), and for survival and replication in RAW 264.7 murine macrophages. We identified 207 in vitro-required genes that were common to both S . enterica Enteritidis strains and also required by S . enterica Typhimurium, S . enterica Typhi and Escherichia coli , and 63 genes that were only required by individual S . enterica Enteritidis strains. Similar types of genes were required by both P125109 and D7795 for optimal growth in particular media. Screening the transposon libraries during macrophage infection identified 177 P125109 and 201 D7795 genes that contribute to bacterial survival and replication in mammalian cells. The majority of these genes have proven roles in Salmonella virulence. Our analysis uncovered candidate strain-specific macrophage fitness genes that could encode novel Salmonella virulence factors.

Discovery of a polymer resistant to bacterial biofilm, swarming, and encrustation.

Innovative approaches to prevent catheter-associated urinary tract infections (CAUTIs) are urgently required. Here, we describe the discovery of an acrylate copolymer capable of resisting single- and multispecies bacterial biofilm formation, swarming, encrustation, and host protein deposition, which are major challenges associated with preventing CAUTIs. After screening ~400 acrylate polymers, poly(tert-butyl cyclohexyl acrylate) was selected for its biofilm- and encrustation-resistant properties. When combined with the swarming inhibitory poly(2-hydroxy-3-phenoxypropyl acrylate), the copolymer retained the bioinstructive properties of the respective homopolymers when challenged with Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Urinary tract catheterization causes the release of host proteins that are exploited by pathogens to colonize catheters. After preconditioning the copolymer with urine collected from patients before and after catheterization, reduced host fibrinogen deposition was observed, and resistance to diverse uropathogens was maintained. These data highlight the potential of the copolymer as a urinary catheter coating for preventing CAUTIs.

Conjugation of Ctx(Ile21)-Ha Antimicrobial Peptides to Chitosan Ultrathin Films by N-Acetylcysteine Improves Peptide Physicochemical Properties and Enhances Biological Activity

The importance of obtaining new compounds with improved antimicrobial activity is a current trend and challenge. Some polymers such as chitosan have shown promising bactericidal properties when they are structurally modified, which is due to the binding versatility provided by their free amines. Likewise, antimicrobial peptides (AMPs) have received attention in recent years because of their bactericidal activity that is similar to or even better than that of conventional drugs, and they exhibit a low induction rate of antimicrobial resistance. Herein, the modified AMP Ctx(Ile21)-Ha-Ahx-Cys was conjugated to chitosan using N-acetylcysteine as an intermediate by the carbodiimide method. Films were prepared using protonated chitosan in 1% acetic acid and Ctx(Ile21)-Ha-Ahx-Cys AMP dissolved in N-acetylcysteine-chitosan; 1.6 mmol of ethylcarbodiimide hydrochloride, 1.2 mmol of N-hydroxysulfosucchimide, and 0.1 mol L –1of N-morpholino)ethanesulfonic acid buffer at pH 6.5 by continuous stirring at 100 × g for 10 min at 37 °C. Physicochemical properties were evaluated by Fourier-transform infrared spectroscopy, differential scanning calorimetry/thermogravimetric analysis, and X-ray diffraction to determine the mechanical properties, solubility, morphology, and thickness. Furthermore, the antimicrobial activities of chitosan-based conjugated films were evaluated againstStaphylococcus aureus,Pseudomonas aeruginosa,SalmonellaTyphimurium, andEscherichia coli. The results showed that the conjugation of a potent AMP could further increase its antibacterial activity and maintain its stable physicochemical properties. Therefore, the developed peptide–chitosan conjugate could be applied as an additive in surgical procedures to prevent and combat bacterial infection.

Synthesis, Biological Screening and Docking Study of Some Novel Pyrazolopyrano[ 2,3-B]quinolin Derivatives as Potent Antibacterial Agents

Background: Pyranopyrazoles have a variety of biological activities and can be obtained by various starting materials and synthetic methods. Also, pyrazolopyrano[2,3-b]quinolins that contain pyranopyrazole moiety have some biological activities such as anti-acetylcholinesterase and anti-butyrylcholinesterase activity. In this research, our objective is to prepare pyranopyrazole compounds and pyrazolopyrano[2,3-b]quinolins in a simple way and then evaluate their antibacterial effect. Methods: In this study, pyrano[2,3-c]pyrazole derivatives have been synthesized by condensing malononitrile, aromatic aldehydes, and 3-methyl-1-phenyl-2-pyrazolin-5-one in the presence of magnesium perchlorate as a catalyst. Then we prepared pyrazolopyrano[2,3-b]quinolins via subsequent Friedlander reaction between cyclohexanone and the obtained pyrano[2,3-c]pyrazoles. Also, the antimicrobial activity of the synthesized pyrazolopyrano[2,3-b]quinolins against Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was measured. Then we studied molecular docking of them to find the predicted compounds' interactions and binding energy with DNA-gyrase with the AutoDock 4.2 software. Results: Pyrazolopyrano[2,3-b]quinolins were synthesized in the optimized conditions. Evaluation of their antibacterial activities showed that these compounds have moderate to good antibacterial activities against four bacteria species. Also molecular docking tests of docked compounds showed a strong bonding interaction with DNA-Gyrase and had been docked into the intercalation place of DNA of DNA-gyrase complex. The molecule bonded to the DNA stabilized by the H bonds, hydrophobic interactions, and π-π interaction. Conclusion: We have developed an efficient and one-pot ecofriendly protocol for the synthesis of some novel pyrano[2,3-c]pyrazol derivatives and pyrazolopyrano[2,3-b]quinolins under simple conditions and then tested them for their antibacterial activities. Also, we studied molecular docking of them. These compounds showed moderate to good inhibitory action.

Clinical and microbiological investigation into mixed growth urine cultures.

Introduction. Urine samples submitted for investigation of urinary tract infection (UTI) may identify more than one bacterial isolate. These samples may be reported as 'mixed growth urine culture' (MGUC). The clinical significance of MGUC remains controversial.Hypothesis/Gap Statement. The impact of MGUC on patient management is not known and should be assessed. To describe MGUC and assess its impact on patient management.Methodology. Microbiology laboratory reports (Leeds, UK) were retrospectively analysed and urine cultures reported as MGUC from a 1 week period underwent detailed laboratory analysis. Semi-structured interviews of NHS clinicians' response to MGUC reports were explored for emergent themes.Results. In 2018, 12.4 % (14,323/115,664) of urine specimens processed to detect bacterial pathogens were reported as MGUC. Among a total of 200 MGUC samples identified within 1 week in 2019, detailed laboratory analysis identified 459 bacterial isolates. Enterococcus species (30.1 %) and Escherichia coli (27.5 %) were the most frequently isolated and the most frequent organism combination (24 %). In total, 65.5 % cultures contained two organisms and 82.5 % of all MGUC contained at least one Enterobacterales. Interviews found clinicians believed MGUC reports represented detection of many commensal bacteria. Clinicians indicated they were more likely to diagnose and treat a UTI when provided with urine culture reports derived from detailed microbial analysis of MGUC, including identity and antibiotic sensitivity of organisms.Conclusions. This study highlights the potential underuse of information derived from microbiological analysis of urine samples. Interpretive commentary on reports together with education for interpretation of enhanced reports should be explored further to improve outcomes in patients with UTI.

Regulatory Evolution of the phoH Ancestral Gene in Salmonella enterica Serovar Typhimurium.

One important event for the divergence of Salmonella from Escherichia coli was the acquisition by horizontal transfer of the Salmonella pathogenicity island 1 (SPI-1), containing genes required for the invasion of host cells by Salmonella. HilD is an AraC-like transcriptional regulator in SPI-1 that induces the expression of the SPI-1 and many other acquired virulence genes located in other genomic regions of Salmonella. Additionally, HilD has been shown to positively control the expression of some ancestral genes (also present in E. coli and other bacteria), including phoH. In this study, we determined that both the gain of HilD and cis-regulatory evolution led to the integration of the phoH gene into the HilD regulon. Our results indicate that a HilD-binding sequence was generated in the regulatory region of the S. enterica serovar Typhimurium phoH gene, which mediates the activation of promoter 1 of this gene under SPI-1-inducing conditions. Furthermore, we found that repression by H-NS, a histone-like protein, was also adapted on the S. Typhimurium phoH gene and that HilD activates the expression of this gene in part by antagonizing H-NS. Additionally, our results revealed that the expression of the S. Typhmurium phoH gene is also activated in response to low phosphate but independently of the PhoB/R two-component system, known to regulate the E. coli phoH gene in response to low phosphate. Thus, our results indicate that cis-regulatory evolution has played a role in the expansion of the HilD regulon and illustrate the phenomenon of differential regulation of ortholog genes. IMPORTANCE Two mechanisms mediating differentiation of bacteria are well known: acquisition of genes by horizontal transfer events and mutations in coding DNA sequences. In this study, we found that the phoH ancestral gene is differentially regulated between Salmonella Typhimurium and Escherichia coli, two closely related bacterial species. Our results indicate that this differential regulation was generated by mutations in the regulatory sequence of the S. Typhimurium phoH gene and by the acquisition by S. Typhimurium of foreign DNA encoding the transcriptional regulator HilD. Thus, our results, together with those from an increasing number of studies, indicate that cis-regulatory evolution can lead to the rewiring and reprogramming of transcriptional regulation, which also plays an important role in the divergence of bacteria through time.

Legionella: A Promising Supplementary Indicator of Microbial Drinking Water Quality in Municipal Engineered Water Systems.

Opportunistic pathogens (OPs) are natural inhabitants and the predominant disease causative biotic agents in municipal engineered water systems (EWSs). In EWSs, OPs occur at high frequencies and concentrations, cause drinking-water-related disease outbreaks, and are a major factor threatening public health. Therefore, the prevalence of OPs in EWSs represents microbial drinking water quality. Closely or routinely monitoring the dynamics of OPs in municipal EWSs is thus critical to ensuring drinking water quality and protecting public health. Monitoring the dynamics of conventional (fecal) indicators (e.g., total coliforms, fecal coliforms, and Escherichia coli) is the customary or even exclusive means of assessing microbial drinking water quality. However, those indicators infer only fecal contamination due to treatment (e.g., disinfection within water utilities) failure and EWS infrastructure issues (e.g., water main breaks and infiltration), whereas OPs are not contaminants in drinking water. In addition, those indicators appear in EWSs at low concentrations (often absent in well-maintained EWSs) and are uncorrelated with OPs. For instance, conventional indicators decay, while OPs regrow with increasing hydraulic residence time. As a result, conventional indicators are poor indicators of OPs (the major aspect of microbial drinking water quality) in EWSs. An additional or supplementary indicator that can well infer the prevalence of OPs in EWSs is highly needed. This systematic review argues that Legionella as a dominant OP-containing genus and natural inhabitant in EWSs is a promising candidate for such a supplementary indicator. Through comprehensively comparing the behavior (i.e., occurrence, growth and regrowth, spatiotemporal variations in concentrations, resistance to disinfectant residuals, and responses to physicochemical water quality parameters) of major OPs (e.g., Legionella especially L. pneumophila, Mycobacterium, and Pseudomonas especially P. aeruginosa), this review proves that Legionella is a promising supplementary indicator for the prevalence of OPs in EWSs while other OPs lack this indication feature. Legionella as a dominant natural inhabitant in EWSs occurs frequently, has a high concentration, and correlates with more microbial and physicochemical water quality parameters than other common OPs. Legionella and OPs in EWSs share multiple key features such as high disinfectant resistance, biofilm formation, proliferation within amoebae, and significant spatiotemporal variations in concentrations. Therefore, the presence and concentration of Legionella well indicate the presence and concentrations of OPs (especially L. pneumophila) and microbial drinking water quality in EWSs. In addition, Legionella concentration indicates the efficacies of disinfectant residuals in EWSs. Furthermore, with the development of modern Legionella quantification methods (especially quantitative polymerase chain reactions), monitoring Legionella in ESWs is becoming easier, more affordable, and less labor-intensive. Those features make Legionella a proper supplementary indicator for microbial drinking water quality (especially the prevalence of OPs) in EWSs. Water authorities may use Legionella and conventional indicators in combination to more comprehensively assess microbial drinking water quality in municipal EWSs. Future work should further explore the indication role of Legionella in EWSs and propose drinking water Legionella concentration limits that indicate serious public health effects and require enhanced treatment (e.g., booster disinfection).

ANTIMICROBIAL PROPERTIES OF RABBIT COLLAGEN GLUE-CHITOSAN BIOMATERIAL LOADED WITH CYMBOPOGON FLEXUOSUS ESSENTIAL OIL

One approach to develop innovative antimicrobial wound dressing materials is to use natural polymers loaded with antimicrobial agents. The valorisation of animal proteins as biomaterials with antimicrobial properties is a new concern for development of wound healing. Plant esssential oils (EO) also indicate a potential approach for new wound dressing materials able to replace the synthetic antymicrobial agents. In this paper, plant-polymeric film was prepared by casting film-forming emulsion based on lemongrass (Cymbopogon flexuosus) essential oil/Tween 80 dispersed into rabbit collagen glue hydrolysate– chitosan biomaterial. The effect of biomaterial film composition on Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 10536 standard bacteria, and Candida albicans ATCC 10231 pathogenic fungus was studied according to European Pharmacopoeia 10/2020 as compared with biomaterial film without essential oil. The in vitro antibacterial tests against three bacterial strains showed that the rabbit collagen glue hydrolysate–chitosan biomaterial inhibited all the three microorganisms. The rabbit collagen hydrolysate glue-chitosan film loaded with lemongrass essential oil exhibits antimicrobial activity towards tested microorganisms but lower as compared with control. The explanation could be due to the short time of investigation, or maybe some active compounds constituents of EO, which favour the cellular proliferation. Preparation of rabbit collagen glue hydrolysate-chitosan biomaterial loaded with lemongrass essential oil is an environmentally friendly solution, which may contribute to the development of wound healing materials as an alternative to topical antimicrobial agents.

Distribution of Antimicrobial Resistance and Virulence Genes within the Prophage-Associated Regions in Nosocomial Pathogens.

ABSTRACTProphages are often involved in host survival strategies and contribute toward increasing the genetic diversity of the host genome. Prophages also drive horizontal propagation of various genes as vehicles. However, there are few retrospective studies contributing to the propagation of antimicrobial resistance (AMR) and virulence factor (VF) genes by prophage. We extracted the complete genome sequences of seven pathogens, including ESKAPE bacteria and Escherichia coli from a public database, and examined the distribution of both the AMR and VF genes in prophage-like regions. We found that the ratios of AMR and VF genes greatly varied among the seven species. More than 70% of Enterobacter cloacae strains had VF genes, but only 1.2% of Klebsiella pneumoniae strains had VF genes from prophages. AMR and VF genes are unlikely to exist together in the same prophage region except in E. coli and Staphylococcus aureus, and the distribution patterns of prophage types containing AMR genes are distinct from those of VF gene-carrying prophage types. AMR genes in the prophage were located near transposase and/or integrase. The prophage containing class 1 integrase possessed a significantly greater number of AMR genes than did prophages with no class 1 integrase. The results of this study present a comprehensive picture of AMR and VF genes present within, or close to, prophage-like elements and different prophage patterns between AMR- or VF-encoding prophage-like elements.IMPORTANCE Although we believe phages play an important role in horizontal gene transfer in exchanging genetic material, we do not know the distribution of the antimicrobial resistance (AMR) and/or virulence factor (VF) genes in prophages. We collected different prophage elements from the complete genome sequences of seven species—Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter cloacae, and Escherichia coli—and characterized the distribution of antimicrobial resistance and virulence genes located in the prophage region. While virulence genes in prophage were species specific, antimicrobial resistance genes in prophages were highly conserved in various species. An integron structure was detected within specific prophage regions such as P1-like prophage element. Maximum of 10 antimicrobial resistance genes were found in a single prophage region, suggesting that prophages act as a reservoir for antimicrobial resistance genes. The results of this study show the different characteristic structures between AMR- or VF-encoding prophages.

Microwave Mediated Fast Synthesis of Silver Nanoparticles and Investigation of Their Antibacterial Activities for Gram-Positive and Gram-Negative Microorganisms

Herein, a simple one-step microwave irradiation technique has been used to synthesize the silver nanoparticles using silver nitrate (AgNO3) solution and cetyltrimethyl ammonium bromide (CTAB) as a stabilizing agent. The crystals of as-prepared nanoparticles were studied using X-ray diffraction (XRD) and a selected area electron diffraction (SAED) pattern, confirming the single-phase face-centered cubic structure. The optical property measured using UV-Vis spectroscopy shows an absorption maximum at 420 nm, which also confirms the formation of silver nanoparticles. Transmission electron microscopy (TEM) analysis revealed that the silver nanoparticles have a spherical shape with an average diameter of ~6 nm. The antibacterial properties of silver nanoparticles were investigated using both Gram-positive and Gram-negative microorganisms, such as Staphylococcus aureus, Pseudomonas aeruginosa, andEscherichia coli. Klebsiella pneumoniae, and Candida albicans. Results showed a highest zone of inhibition of about 35 mm against P. aeruginosa as compared with E. coli (21 mm), S. aureus (30 mm), K. pneumonia (28 mm), and C. albicans (29 mm). These studies suggested that silver nanoparticles prepared by this fast and effective method might be developed as antibacterial agents against an extensive range of microorganisms to control and stop the spreading and persistence of bacterial infections.

S-Nitroso-N-acetyl-l-cysteine Ethyl Ester (SNACET) Catheter Lock Solution to Reduce Catheter-Associated Infections.

Antimicrobial-lock therapy is an economically viable strategy to prevent/reduce the catheter-related bloodstream infections (CRBSI) that are associated with central venous catheters (CVCs). Herein, we report the synthesis and characterization of the S-nitroso-N-acetyl-l-cysteine ethyl ester (SNACET), a nitric oxide (NO)-releasing molecule, and for the first time its application as a catheter lock solution to combat issues of bacterial infection associated with indwelling catheters. Nitric oxide is an endogenous gasotransmitter that exhibits a wide range of biological properties, including broad-spectrum antimicrobial activity. The storage stability of the SNACET and the NO release behavior of the prepared lock solution were analyzed. SNACET lock solutions with varying concentrations exhibited tuneable NO release at physiological levels for >18 h, as measured using chemiluminescence. The SNACET lock solutions were examined for their efficacy in reducing microbial adhesion after 18 h of exposure toStaphylococcus aureus (Gram-positive bacteria) andEscherichia coli (Gram-negative bacteria). SNACET lock solutions with 50 and 75 mM concentrations were found to reduce >99% (ca. 3-log) of the adhered S. aureus and E. coli adhesion to the catheter surface after 18 h. The SNACET lock solutions were evaluated in a more challenging in vitro model to evaluate the efficacy against an established microbial infection on catheter surfaces using the same bacteria strains. A >90% reduction in viable bacteria on the catheter surfaces was observed after instilling the 75 mM SNACET lock solution within the lumen of the infected catheter for only 2 h. These findings propound that SNACET lock solution is a promising biocidal agent and demonstrate the initiation of a new platform technology for NO-releasing lock solution therapy for the inhibition and treatment of catheter-related infections.

Effect of dietary supplementation with powder derived fromMoringa oleifera andAzadirachta indica leaves on growth and microbial load of edible crickets

Cricket farming has shown its potential to address food and nutrition insecurity in parts of the world. However, one of the remaining challenges limiting mass production of edible insects is the affordability of feeds. One possible way to address this issue would be to explore the use of traditional plants such asMoringa oleifera leaf (MOL) andAzadirachta indica leaf (AIL) that are locally available, are protein-rich and possesses some antibacterial properties in insect feed formulation. In this regard, a study was conducted to evaluate the effect of supplementation of MOL (5 or 10%) and AIL (5 or 10%) powder in the commercially used starter chicken feed on growth and microbial load of house cricket (Acheta domesticus) and field cricket (Gryllus bimaculatus). After feeding for four weeks, the supplemented feeds with 10% MOL or 10% AIL inA. domesticus andG. bimaculatus significantly decreased (P<0.05) the body weights. Also, supplementation with MOL (5 or 10%) and AIL (5 or 10%) increased the mortality in both cricket species. Although high counts of total aerobic,Enterobacteriaceae, lactic acid bacteria, bacterial endospores, yeasts and moulds were observed, significantly lower counts (P<0.05) of lactic acid bacteria and bacterial endospores were observed in treatments containing MOL (5 or 10%) and 10% AIL in both cricket species. After processing (toasting and boiling), significant reductions (P<0.001) of all vegetative microbial cells were observed but bacterial endospores were not completely eliminated. Thus, during production and processing of insects and insect-derived products, bacterial endospores would require special attention.Salmonella andEscherichia coli were not detected in processed crickets’ samples. In conclusion, supplementation with 5% MOL or 5% AIL can produce crickets with similar body weight as control feed. Mortality increased significantly when feeds were supplemented with either MOL or AIL powder. Supplementation with MOL and AIL powders significantly reduced the cell numbers for some bacterial groups in both cricket species.

In vitro growth-inhibitory effects of Portulaca oleracea L. formulation on intestinal pathogens.

Introduction Empirical evidence suggests that Portulaca oleracea L. treats enteric infections, including dysentery, cholera, and acute infectious gastroenteritis.Aim The aim of this study is to clarify the growth-inhibitory effects of Portulaca oleracea L. extract against 56 strains of intestinal pathogens.Methodology ‘Gogyo-so-cha (GSC)’ was used as the P. oleracea L. formulation. A growth curve analysis was used to measure the growth-inhibitory effects of GSC, and Shiga toxin induction was measured using the latex agglutination test.Results GSC demonstrated strong bactericidal effects against Shigella dysenteriae and Vibrio cholerae strains from various isolates. GSC demonstrated weak or no bactericidal effects against intestinal commensal bacteria, including Enterococcus spp. and Escherichia coli . GSC did not induce Shigella toxins.Conclusion GSC significantly inhibited the growth of intestinal pathogens, including S. dysenteriae and V. cholerae , without adversely affecting the intestinal flora, supporting the usage of GSC in traditional Chinese medicine. Taken together, GSC would be of immense value in the developing world, where diarrhoeal infectious diseases continue to pose a major health risk.

Growth promotion of some lactic acid bacteria by crude extract of Spirogyra sp., Cladophora sp., Caulerpa lentillifera and Caulerpa corynephora

The aim of this research was to evaluate the growth promotion of two freshwater macroalgae (Spirogyra sp., Cladophora sp.) and two saltwater macroalgae (Caulerpa lentillifera and Caulerpa corynephora) crude extracts to some lactic acid bacteria using in vitro fermentation. Total soluble carbohydrates of macroalgae were obtained after extraction with 75oC of water for 1 hr. The concentration of total sugar and reducing sugar were 0.764 and 0.197 mg/g in Spirogyra sp., 0.368 and 0.082 mg/g in Cladophora sp., 0.484 and 0.055 mg/g in C. lentillifera, and 0.253 and 0.037 mg/g in C. corynephora, respectively. Degree of polymerization (DP) that refers to the size of oligosaccharide, were 3.8, 4.5, 8.8 and 6.8, respectively. The prebiotic activity was assessed by the change of the bacterial population. Crude extracts from macroalgae were tested for growth stimulation effect on lactic acid bacteria, Lactobacillus plantarum TISTR862 and Escherichia coli TISTR073. Results demonstrated that the population of L. plantarum TISTR862 and E. coli TISTR073 were higher in crude extracts from freshwater than saltwater macroalgae. The prebiotic activity score was calculated based on the change of growth in probiotic and pathogen after 24 hrs of incubation time. The highest score was obtained from C. corynephora extracts (1.10) follow by C. lentillifera extracts (0.77), Cladophora sp. extracts (0.173) and Spirogyra sp. extracts (0.07). In comparison with commercial culture (Lactobacillus casei, Lactobacillus lactis, Streptococcus thermophilus and Bifidobacterium), the addition of 3.5% C. lentillifera extracts resulted as prebiotic activity score value as 3.5% FOS. Preliminary study demonstrated that crude extract of C. lentillifera could be a prebiotic substance

Foodborne bacteria in raw drone brood ofApis mellifera – a preliminary survey

Drone brood ofApis mellifera is often removed from the beehive to control the honeybee parasiteVarroa destructor. Instead of discarding the drone brood, it could rather be used as a new food source for human nutrition. However, studies on microbiological hazards caused by edible insects are rare, especially in the case of drone brood. In this survey, microbial total viable cell counts and the most common foodborne bacteria were assessed in raw drone brood. Samples were taken from 24 beehives from four apiaries in Switzerland. The drone brood combs were harvested either by the beekeepers with their personal equipment or by the researchers with sterile equipment. No difference in the total viable cell counts was found between these two methods. All samples were free ofSalmonella. Viable counts ofBacillus cereus, coagulase-positive staphylococci, Enterobacteriaceae andEscherichia coli were all below the detection limits of the recommended ISO reference methods. However,Listeria monocytogenes was detected in eight samples (all <10 cfu/g), which has not been reported in edible insects until now.

Antibacterial activity of human defensins against Staphylococcus aureus and Escherichia coli.

BackgroundThe global problem of antibiotic resistance requires the search for and development of new methods of treatment. One of the promising strategies is the use of low doses of antimicrobial peptides, in particular, human defensins HNP-1, hBD-1, and hBD-3, in combination with antibacterial drugs already used in clinical practice. This approach may be used to increase the effectiveness of conventional antibiotics. However, this requires thorough study of the effectiveness of defensins in combination with antibiotics against a large number of bacterial strains with known phenotypes of antibiotic resistance. The aim of this work was to study the antibacterial effect of HNP-1, hBD-1 and hBD-3 in combination with rifampicin or amikacin against clinical isolates of Staphylococcus aureus (n = 27) and Escherichia coli (n = 24) collected from hospitalized patients.MethodsThe standard checkerboard assay was used to determine minimum inhibitory concentrations (MICs) of antimicrobials. The combined microbicidal effects of two substances (defensin + conventional antibiotic) were assessed by the fractional inhibitory concentration index (FICI).ResultsThe highest anti-staphylococcal activity (including methicillin-resistant strains) among defensins was demonstrated by hBD-3 that had MIC of 1 (0.5–4) mg/L (hereinafter, MIC values are presented as median and interquartile range). The MIC of HNP-1 against S. aureus was 4 (2–8) mg/L; the MIC of hBD-1 was 8 (4–8) mg/L. Against E. coli, the most effective was also found to be hBD-3 that had MIC of 4 (4–8) mg/L; the MIC of HNP-1 was 12 (4–32) mg/L. The combinations of HNP-1 + rifampicin and hBD-3 + rifampicin demonstrated synergistic effects against S. aureus. Against E. coli, combinations of HNP-1 + amikacin and hBD-3 + amikacin also showed synergy of action.