Preparation and properties of hydrogels loaded with phage endolysin Lys84 / 生物工程学报

This study investigated the application of poly(N-isopropylacrylamide)-based interpenetrating network temperature-sensitive hydrogels (notation: IPNT) as the delivery vehicle for phage endolysin Lys84 and the potential of drug-loaded hydrogels as antimicrobial materials. Interpenetrating network temperature-sensitive hydrogels were prepared by free radical polymerization of sodium alginate and N-isopropylacrylamide. Drug-loaded hydrogels (IPNT-Lys84) were obtained by dry soaking method with the endolysin Lys84 of Staphylococcus aureus phage. The physical properties of the hydrogels with and without drug loading were characterized by infrared spectroscopy, scanning electron microscopy, and differential scanning calorimetry. The swelling and deswelling of the hydrogels as well as the release of endolysin Lys84 were investigated. Moreover, the antibacterial properties of IPNT-Lys84 hydrogels at different temperatures and concentrations of the drug solution were studied. The results showed that IPNT-Lys84 hydrogel had uniform pores and a low critical solubility temperature (LCST) of 32 ℃. The equilibrium swelling of the hydrogel was 30 g/g, and the water loss rate was 88% upon deswelling. The release rate of endolysin reached more than 70% within 6 h at 37 ℃. The bactericidal rate of IPNT-Lys84 hydrogel was over 99.9%. The research results showed the feasibility of using IPNT to deliver the endolysin Lys84, and IPNT-Lys84 hydrogel might be an effective antimicrobial material against multi-drug resistant Staphylococcus aureus.

Preparation, properties and antibacterial applications of medical nano-metals and their oxides: a review / 生物工程学报

Antibiotics are playing an increasingly important role in clinical antibacterial applications. However, their abuse has also brought toxic and side effects, drug-resistant pathogens, decreased immunity and other problems. New antibacterial schemes in clinic are urgently needed. In recent years, nano-metals and their oxides have attracted wide attention due to their broad-spectrum antibacterial activity. Nano-silver, nano-copper, nano-zinc and their oxides are gradually applied in biomedical field. In this study, the classification and basic properties of nano-metallic materials such as conductivity, superplasticity, catalysis, and antibacterial activities were firstly introduced. Secondly, the common preparation techniques, including physical, chemical and biological methods, were summarized. Subsequently, four main antibacterial mechanisms, such as cell membrane, oxidative stress, DNA destruction and cell respiration reduction, were summarized. Finally, the effect of size, shape, concentration and surface chemical characteristics of nano-metals and their oxides on antibacterial effectiveness and the research status of biological safety such as cytotoxicity, genotoxicity and reproductive toxicity were reviewed. At present, although nano-metals and their oxides have been applied in medical antibacterial, cancer treatment and other clinical fields, some issues such as the development of green preparation technology, the understanding of antibacterial mechanism, the improvement of biosafety, and the expansion of application fields, require further exploration.

Antibacterial and osteogenic properties of vancomycin/PLGA-coated porous magnesium alloy scaffolds / 中华创伤骨科杂志

Objective:To evaluate the physicochemical properties, degradation and drug release behaviour, cytocompatibility and bacteriostatic properties in vitro of porous magnesium alloy scaffolds containing vancomycin/poly(lactic-co-glycolic acid) (PLGA). Methods:Porous magnesium scaffolds (Mg-2Zn-0.3Ca) were prepared using the template replication technique. The MgF 2 surface layer was obtained by high temperature fluorination. The vancomycin/PLGA porous magnesium alloy drug-loaded scaffolds were obtained by homogeneous lifting after submersion in a dichloromethane solution of PLGA containing vancomycin hydrochloride. According to the products at each stage of the preparation (scaffolds of magnesium alloy, magnesium fluoride alloy, PLGA coated magnesium fluoride alloy, and vancomycin/PLGA magnesium fluoride alloy), they were divided into an Mg group, an MgF 2 group, a PLGA group, and a vancomycin/PLGA group. Immediately after preparation, the material science characterization, degradation rate, drug release rate, antibacterial properties, hemocompatibility, and cell proliferation and differentiation ability of the scaffolds were measured and evaluated. Results:Vancomycin-loaded magnesium alloy scaffolds were successfully prepared with an average porosity of 66.39%. Their degradation rate [(0.540±0.102) mm/year] was significantly lower than that of the Mg ones [(10.048±0.297) mm/year] ( P<0.05). Their pH of degradation in Hank equilibrium salt solution was close to the physiological pH. Their release of vancomycin was fast in the first 48 h and gradually slowed down after 48 h. Their cumulative drug concentration reached a maximum of 43 mg/L at d 11; their vancomycin was still released slowly after d 11. The antimicrobial rate in the vancomycin/PLGA group (97.89%±0.28%) was significantly higher than that in the Mg group (74.92%±2.20%), the MgF 2 group (78.46%±2.59%) and the PLGA group (61.08%±4.21%) ( P<0.05). Their hemolysis rate (0.55%) was much lower than the requirement of ISO 10993-4 (5%). The extract liquid from them promoted the proliferation of rat bone marrow mesenchymal stem cells (BMSCs), showing a gradually increased proliferation rate from d1 (104.80%±5.13%) to d3 (112.36%±2.07%) and d7 (127.79%±4.61%). The calcium nodules in BMSCs were significantly increased at d 14, with an OD value of absorbance of 1.189±0.020, significantly higher than that in the Mg group (0.803±0.020), the MgF 2 group (0.878±0.028) and the PLGA group (0.887±0.026) ( P<0.05). Conclusion:Vancomycin/PLGA-loaded porous magnesium alloy scaffolds exhibit good material properties, antibacterial properties, biocompatibility and osteogenic properties in vitro.

Preparation and antibacterial properties of Cu-ZnO-loaded dental veneering porcelain / 口腔疾病防治

Objective@#To investigate the antibacterial properties, biocompatibility and mechanical properties of Cu-ZnO-loaded dental veneering porcelain to provide an experimental basis for the development of new dental veneering porcelain. @*Methods@#Cu-ZnO nanoparticles were added to IPS E.max Ceram for restorative veneer porcelain at different mass percentages of 0 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, and 6 wt% using ball milling in ceramic powder. A cylindrical specimen with a diameter of 20 mm and a thickness of 2 mm was prepared by high-temperature sintering. Scanning electron microscopy was used to observe the surface morphologies of nano-Cu-ZnO and the specimens. The antibacterial effect of Escherichia coli (E. coli) was quantitatively studied by the plate colony counting method. The CCK-8 method was used to evaluate in vitro the cytotoxicity of the tested piece to mouse fibroblasts (L929). Live and dead cells were observed by fluorescence microscopy. The mechanical properties of modified IPS E. Max Ceram veneering porcelain were tested by a three-point bending strength test. @* Results @# Under the scanning electron microscope, Cu-ZnO appears with a block-like structure and can be seen dispersed in the veneering porcelain. When the nano Cu-ZnO loading was 1 wt%, 2 wt%, 3 wt%, and 4 wt%, the antibacterial rates of the specimens were 24.85%, 67.94%, 96.92%, and 99.99%, respectively, and the difference between the experimental groups and the control group was statistically significant (F = 23.308,P = 0.001). The relative growth rate of each group was greater than 80% after coculture with mouse fibroblast cells (L929) for 1 day and 3 days, and there was no significant difference between the groups. The morphology of L929 cells was normal after coculture for 24 hours. With the increase in the Cu-ZnO concentration, the flexural strength of the specimen exhibited an increasing trend followed by a decreasing trend. The bending strength of the specimen loaded with 3 wt% nano Cu-ZnO reached the maximum value (84.728 ± 6.82) MPa, and there was no statistically significant difference between groups (F = 0.633,P = 0.702).@*Conclusion@#The antibacterial rate of IPS E. max Ceram veneering porcelain loaded with 3 wt% nano Cu-ZnO was more than 96% against E. coli after high-temperature sintering at 750 ℃. The bending strength reached the maximum (84.728 ± 6.82) MPa, and there was no obvious cytotoxicity.

Research progress about photothermal nanomaterials with targeted antibacterial properties and their applications in wound healing / 生物医学工程学杂志

With the development of photothermal nanomaterials, photothermal therapy based on near-infrared light excitation shows great potential for the bacterial infected wound treatment. At the same time, in order to improve the photothermal antibacterial effect of wound infection and reduce the damage of high temperature and heat to healthy tissue, the targeted bacteria strategy has been gradually applied in wound photothermal therapy. In this paper, several commonly used photothermal nanomaterials as well as their targeted bacterial strategies were introduced, and then their applications in photothermal antibacterial therapy, especially in bacterial infected wounds were described. Besides, the challenges of targeted photothermal antibacterial therapy in the wound healing application were analyzed, and the development of photothermal materials with targeted antibacterial property has prospected in order to provide a new idea for wound photothermal therapy.

Antibacterial Properties of Hydrogel Membranes Infused with Liquid Smoke on Growth Inhibition of Staphylococcus aureus

@#Introduction: Staphylococcus aureus is the most common bacteria infecting chronic wounds. Wound dressing are available in various physical forms including hydrogels. However, hydrogels are expensive and contain synthetic materials, so natural materials such as liquid smoke infusing to the hydrogels will be improve its composition and needed as antibacterial wound dressing. This study analysed the difference in antibacterial activity between a hydrogel base and hydrogel membranes infused with liquid smoke to inhibit the growth of S. aureus. Methods: This study was a true laboratory experiment with a post-test only control group design. Twenty-four samples were divided into four concentration groups of 0%, 8%, 12% and 16%. The parallel streak method (AATCC 147-2004) was used for antibacterial testing. Data were analysed using Kruskall-Wallis and Mann-Whitney tests. Results: The average clear zone widths of inhibition of S. aureus at 0%, 8%, 12% and 16% were 0.013 mm, 0.416 mm, 1.191 mm and 1.625 mm respectively. The Mann-Whitney test indicated significant difference in the width of the inhibition zone between 0% and 12% and 16%, and between 8% and 16% (p<0.05). The hydrogel membrane infused with liquid smoke at a concentration of 12% was the lowest concentration that inhibited S. aureus. Conclusion: Hydrogel membranes infused with liquid smoke had antimicrobial properties against growth inhibition of S. aureus.

Optimisation of topical antibacterial preparation from Malaysian kelulut honey by using xanthan gum as polymeric agent

@#The study aims to formulate and optimise topical antibacterial preparation by using Malaysian kelulut honey as the active ingredient and xanthan gum as the polymeric agent. Response surface methodology was used to optimise the preparation. The acidity, honey concentration and xanthan gum concentration were the independent variables. The zone of inhibitions on S. aureus ATCC6538 and E. coli ATCC8739 were the response variables. The optimal preparation was evaluated on its physicochemical properties, viscosity, antibacterial efficacy and stability. The antibacterial efficacy of the optimal preparation was compared to the commercially antibacterial gel (MediHoney™, Comvita). The optimal preparation was formulated at pH of 3.5, honey concentration of 90% (w/v) and xanthan gum concentration of 1.5% (w/v) with the inhibition zones measured on S. aureus ATCC6538 was 16.2 mm and E. coli ATCC8739 was 15.8 mm respectively. The factors of acidity and honey concentration have significantly influenced the inhibition zone on S. aureus ATCC6538 and E. coli ATCC8739. The utilisation of xanthan gum as the polymeric agent was fit for the preparation which showed by adequate physicochemical properties and retained of the antibacterial effects. This was supported by constant viscosity and efficacy of the preparation within the six months of stability study indicating stable and reliable preparation. Xanthan gum is a potential polymeric agent due to its effective use in preparing stable preparation with effective antibacterial properties.

Characteristics of selenium nanoparticles synthesized by cell-free supernatant Cupriavidus sp. SHE / 生物工程学报

In recent years, selenium nanoparticles (SeNPs) have been widely used in many fields such as nanotechnology, biomedicine and environmental remediation due to their good electrical conductivity, photothermal properties and anticancer properties. In this study, the cell-free supernatant, whole cell and the cell-free extracts of the strain Cupriavidus sp. SHE were used to synthesize SeNPs, and several methods were applied to analyze the crystal structure and surface functional groups of the nanoparticles. Finally, Pseudomonas sp. PI1 (G⁺) and Escherichia coli BL21 (G⁻) were selected to investigate the antibacterial properties of SeNPs. Cell-free supernatant, whole cell and cell-free extracts of the strain could synthesize SeNPs. As for the cell-free supernatant, selenite concentration of 5 mmol/L and pH=7 were favorable for the synthesis of SeNPs. TEM images show that the average size of nanospheres synthesized by the supernatant was 196 nm. XRD analysis indicates the hexagonal crystals structure of SeNPs. FTIR and SDS-PAGE confirmed the proteins bound to the surfaces of SeNPs. SeNPs synthesized by cell-free supernatant showed no antimicrobial activities against Pseudomonas sp. PI1 and Escherichia coli BL21 (DE3). These results suggest that proteins played an important role in biotransformation of SeNPs in an eco-friendly process, and SeNPs synthesized in this study were non-toxic and biologically compatible, which might be applied in other fields in the future.

Mechanical strength and inhibition of plaque biofilm activity of a novel antibacterial Hawley retainer / 口腔疾病防治

Objectives @#The purposes of this study were to evaluate the long-term mechanical property, bacteria-killing ability, protein resistance and cytotoxicity of a novel antibacterial methyl methacrylate (MMA) resin. @*Methods @#The 2-methacryloyloxyethyl phosphorylcholine (MPC) has been added into the MMA used for making Hawley orthodontic retener according to the mass percentage 0% (control group), 1.5%, 2.25%, 3%, 4.5% and 6%. Specimens from the control group and MPC group were water-aged for 1 d, 90 d and 180 d, and then the universal material testing machine was used to investigate the long-term mechanical properties of the modified MMA specimens in the oral environment. The biofilm metabolic activity, colony-forming unit (CFU) and live/dead staining assay of the biofilms in the control group and MPC group in the oral environment were tested using the dental plaque biofilm model. The micro-bicinchoninic acid (BCA) method was used to determine the amount of protein adsorbed on the specimens. The MTT method was used to evaluate the cytotoxicity of the control group and MPC group.@*Results @#In the simulated oral environment, the addition of 0% to 3% MPC had no significant effect on the mechanical properties of the MMA specimen (P > 0.05). The control group and the modified MMA specimens with 3%MPC were statistically significant in time and the interaction effects between the two groups (P < 0.05). With increasing intervention time, the mechanical strength of both groups decreased, and the effect of time varied with grouping. The protein adsorption on the surface of the modified MMA material after adding 3% MPC decreased by approximately 80%, the metabolic activity of the biofilm decreased by approximately 50%, and biofilm CFU counts decreased by approximately 70% (P < 0.05) compared with the control. There was no statistically significant difference in time or interaction effects between the two groups. The amount of live green bacteria in the 3% MPC group decreased significantly after 1, 90, and 180 d of water aging. There was no significant difference in cytotoxicity between the control group and the MPC group (P > 0.05). @*Conclusions @#The addition of MPC into the MMA resin did not compromise the mechanical properties of the resin and exhibited long-lasting antibacterial and protein-repellent effects.

Antibacterial Activity of Sophorolipids from Candida bombicola Against Human Pathogens

Abstract Sophorolipids are glycolipids that have natural antimicrobial properties and present great potential in the pharmaceutical field. The present study aimed to produce sophorolipids from Candida bombicola using a chicken fat-based medium and evaluate the antimicrobial activity against Gram-negative (Proteus mirabilis, Escherichia coli, Salmonella enterica subsp. enterica) and Gram-positive bacteria (Enterococcus faecium, Staphylococcus aureus and Streptococcus mutans). The production of sophorolipids reached 27.86 g L-1. Based on the structural characterization, 73.55% of the sophorolipids present a mixture of acidic monoacetylated C18:2 and lactonic diacetylated C16:0, and 26.45% were present in the diacetylated C18:1 lactonic form. Bacteria submitted to sophorolipid exposure showed a reduction in viability at doses of 500 μg mL-1 and 2,000 μg mL-1 against Gram-positive and Gram-negative bacteria, respectively. These results suggest that sophorolipids produced in chicken fat medium may be used as antimicrobial agents to prevent or eliminate contamination by different pathogens.

In vitro Antibacterial Properties of Etlingera elatior Flower Extracts against Acne-Inducing Bacteria: Propionibacterium acnes and Staphylococcus aureus

@#Introduction: Acne is a common skin disorder and is generally caused by Propionibacterium acnes and Staphylococcus aureus. Etlingera elatior flower extract is known to have antibacterial properties however, the properties against these bacteria have not been extensively reported. Thus, this study aimed to investigate the antibacterial properties of the flower extract against these bacteria. Materials and Methods: The flower extract was subjected to sequential extraction using three different solvent polarities; n-Hexane, dichloromethane (DCM) and ethanol. The antibacterial properties were evaluated using the disc diffusion and broth dilution assays techniques by determining the inhibition zone diameter, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Total phenolic acids (TPC) and flavonoids contents (TFC) were estimated using Folin-Ciocalteu and aluminium-chloride colorimetric assay respectively. Morphological changes of the treated bacteria were studied using scanning electron microscope (SEM). Results: DCM flower extract showed the highest antibacterial properties against P. acnes; at 25 mg/ml it had the widest inhibition zone (11.39 ± 0.45 mm) and the lowest MIC (6.25 mg/ mL) and MBC (12.5 mg/mL). The ethanolic flower extract had the highest antibacterial properties against S. aureus; at 50 mg/ml­ the inhibition zone was 6.21 ± 0.25 mm and the MIC and MBC were both 12.5 mg/ mL. Ethanolic extracts had the highest TPC (966.304 ± 114.08 mg GAE/g) and TFC (796.33 ± 65.78 mg QE/ g). There was significant morphological changes of the treated bacteria observed under SEM. Conclusion: E. elatior flower extracts exhibited antibacterial properties against acne-inducing bacteria.

Advances in the research of antibacterial properties of silver ion and its application in wound treatment / 中华烧伤杂志

Nowadays, antibacterial products containing silver ion are widely used in clinical wound treatment. The concentration of silver ion in products, pH value, and other factors may affect the release of silver ion and its antibacterial effects. In the treatment of clinical wound, silver ion product plays a good role in anti-infection, promoting healing and reducing medical expenses. In this paper, the related applications of silver ion products in wound surface are analyzed, and the antibacterial properties of silver ion and its therapeutic effects in wound treatment are summarized.

The Antibacterial Properties of Euphorbia Tirucalli Stem Extracts against Dental Caries-Related

Euphorbia tirucalli are reported to possess antibacterial activity against various microorganisms. This in vitro study aimed to evaluate the antibacterial properties of Euphorbia tirucalli stems extracts (methanol, ethanol and aqueous extracts) against dental caries-related bacteria, i.e. Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus). The antibacterial properties were determined using agar-well diffusion method at different extract concentrations (10, 20 and 30 mg/ml). Commercially available amoxicillin (10 µg) was used as positive control while the appropriate solvent served as negative control. The methanolic and ethanolic extracts of Euphorbia tirucalli stem were found to be effective against S. mutans and S. sobrinus. However, the aqueous extract of Euphorbia tirucalli stem showed no activity against both bacterial strains. The differences in the antibacterial properties in different extracts of Euphorbia tirucalli may be due to the differences in phytochemical constituents.

Antimicrobial activity of Anonna mucosa (Jacq.) grown in vivo and obtained by in vitroculture

Brazilian flora includes numerous species of medicinal importance that can be used to develop new drugs. Plant tissue culture offers strategies for conservation and use of these species allowing continuous production of plants and bioactive substances. Annona mucosa has produced substances such as acetogenins and alkaloids that exhibit antimicrobial activities. The widespread use of antibiotics has led to an increase in multidrug-resistant bacteria, which represents a serious risk of infection. In view of this problem, the aim of this work was to evaluate the antibacterial potential of extracts of A. mucosa obtained by in vitro techniques and also cultured under in vivo conditions. Segments from seedlings were inoculated onto different culture media containing the auxin picloram and the cytokinin kinetin at different concentrations. The calluses obtained were used to produce cell suspension cultures. The materials were subjected to methanol extraction and subsequent fractionation in hexane and dichloromethane. The antimicrobial activity against 20 strains of clinical relevance was evaluated by the macrodilution method at minimum inhibitory and minimum bactericidal concentrations. The extracts showed selective antimicrobial activity, inhibiting the growth of Streptococcus pyogenes and Bacillus thuringiensis at different concentrations. The plant tissue culture methods produced plant materials with antibacterial properties, as well as in vivo grown plants. The antibacterial activity of material obtained through biotechnological procedures of A. mucosa is reported here for the first time.

Antimicrobial properties of titanium soaked with benzalkonium chloride solution / 实用口腔医学杂志

Objective:To study the antibacterial properties of pure titanium treated with benzalkonium chloride solution.Meth-ods:10 mm ×10 mm ×1 mm titanium specimens were processed by the benzalkonium chloride solution at 1%,0.5% and 0.1%respectively followed by treatment in the cultured bacterial suspension,and then the antibacterial properties of the titanium plates were examined.Additionally,the thermal cycling test was carried out for the 1% benzalkonium chloride-treated titanium plates, and subsequently put the plates into cultured bacterial suspension,the duration of antibacterial properties was observed.Results:0.5% and 1% benzalkonium chloride solution-treated titanium plates significantly inhibited the growth of candida albicans(P <0. 05),1% solution was more effective than 0.5% solution.After 1 000 and 2 500 thermal cycling,the pure titanium still retained the antibacterial ability,but the plates treated by 5 000 cycling showed no antibacterial effect.Conclusion:A certain concentration of benzalkonium chloride can make the pure titanium obtain antibacterial properties.The treated plates may maintain the antibacte-rial properties for a minimum of 3 months.

Chemical composition and antibacterial properties of the essential oil and extracts of Lantana camara Linn. from Uttarakhand (India)

Objective: The purpose of this study was to evaluate the essential oil composition as well as antibacterial activities of essential oil and leaves extracts of Lantana camara against five bacterial strains. Methods: Essential oil was obtained by hydro-distillation from the leaves and analyzed by GC and GC-MS. The antibacterial activities of essential oil and the leaves extracts were tested by using disk diffusion method against five bacterial strains. Results: Thirty seven compounds were identified representing 98.11% of the total oil, of which trans-caryophyllene (13.95%), bicyclogermacrene (9.77%), α-curcumene (8.57%), sabinene (8.28%), (E)-citral (6.90%), 1,8 cineole (5.06%), α-pinene (4.03%), γ-terpinene (3.83%) and germacrene D (3.13%) were detected as major components. In respect to the antibacterial activities, essential oil showed the high degree of sensitivity against Micrococcus luteus, Escherichia coli, Staphylococcus aureus and Bacillus cereus except Pseudomonas aeruginosa while extracts of leaves obtained through petroleum ether, benzene, methanol and water exhibited good to moderate antimicrobial activity against all tested bacterial strains. Conclusions: The present study suggested that M. luteus showed best zone of inhibition for the essential oil as well as aqueous extract among all the tested bacterial strains. The most active extract can be subjected to isolation of the therapeutic antimicrobials to carry out further pharmacological evaluation.

Atividade antimicrobiana de óleos essenciais em bactérias patogênicas de origem alimentar / Antimicrobial activity of essential oils against sessile and planktonic pathogens of food source

Objetivou-se identificar e quantificar os constituintes e avaliar a atividade antimicrobiana dos óleos essenciais de Mentha piperita, Cymbopogon citratus, Ocimum basilicum e Origanum majorana contra cepas de Escherichia coli enteropatogênica, Salmonella enterica Enteritidis, Listeria monocytogenes e Enterobacter sakazaki. A obtenção dos óleos essenciais foi realizada a partir de folhas secas, empregando-se a técnica de hidrodestilação e utilizando-se a aparelho de Clevenger modificado. A atividade antibacteriana dos óleos essenciais foi determinada pelo método de difusão em ágar. Observou-se que os óleos essenciais inibiram o crescimento bacteriano, mas a efetividade foi variada. Entre os óleos essenciais testados, M. piperita apresentou maior atividade antibacteriana para E. coli, (8.106 UA mL-1) quando comparada as demais bactérias, atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 3.200 UA mL-1 respectivamente) e baixa atividade para Listeria monocytogenes (106,67 UA mL-1). Já óleo essencial de Cymbopogon citratus apresentou maior atividade antimicrobiana frente a E. coli (9.386 UA mL-1) e atividade moderada frente a Enterobacter sakazakii, Salmonella enterica Enteritidis e Listeria monocytogenes (2.773 UA mL-1 para ambas). Ocimum basilicum apresentou maior atividade antibacteriana frente E. coli e Enterobacter sakazakii (6.826 e 8.106 UA mL-1 respectivamente), moderada atividade frente a Salmonella enterica Enteritidis (1.600 UA mL-1) e não apresentou atividade frente a Listeria monocytogenes.Origanum majorana também foi testado neste estudo e apresentou maior atividade antimicrobiana frente E. coli (5.973 UA mL-1), atividade moderada para Salmonella enterica Enteritidis e Enterobacter sakazakii (1.706 e 2.346 UA mL-1 , respectivamente) e não apresentou atividade para Listeria monocytogenes.

ABSTRACT The objective of this work was to identify and quantify the constituents, and to evaluate the antimicrobial activity of the essential oils from Mentha piperita, Cymbopogon citratus, Ocimum basilicum and Origanum majorana, against enteropathogenic Escherichia coli, Salmonella enterica Enteritidis, Listeria monocytogenes and Enterobacter sakazakii. The essential oils were obtained from dried leaves by using the hydrodistillation technique and the modified Clevenger apparatus, and their bacterial activity was determined by using the agar diffusion technique. The essential oils inhibited bacterial growth, but their effectiveness was varied. Among the essential oils tested, that from M. piperita showed a greater antimicrobial activity against E. coli (8.106 UA mL-1), moderate activity for S. enterica Enteritidis and E. sakazakii (1.706 e 3.200 UA mL-1 respectively) and low activity for L. monocytogenes (106,67 UA mL-1). However, the essential oil from C. citratus presented a greater antimicrobial activity against E. coli (9.386 UA mL-1) and a moderate activity against E. sakazakii, S. enterica Enteritidis and L. monocytogenes (2.773 UA mL-1 for both). The essential oil from O. basilicum showed a greater antimicrobial activity against E. coli and E. sakazakii (6.826 e 8.106 UA mL-1 respectively),moderate activity against S. enterica Enteritidis (1.600 UA mL-1), and was inactive against L, monocytogenes. Origanum majorana, which was also tested in our work, showed a greater antibacterial activity against E. coli, (5.973 UA mL-1) moderate activity against S. enterica Enteritidis and E. sakazakii (1.706 e 2.346 UA mL-1 , respectively), and was inactive against L. monocytogenes.

Antibacterial properties of punica granatum peels.

The main aim of this study is that due to increasing concerns about the development of antimicrobial resistance among pathogenic bacteria, so alternative strategies are sought that do not use antibiotics to reduce pathogenic bacteria from foods and patients. Plants have been in use for thousands of years to conserve food and treat health diseases. The pericarp (peels) of Punica granatum has been commonly employed as a crude drug in Indian traditional medicine for treatment of diarrhea as well as for use as an antihelminthic, diuretic, stomachic, cardiotonic. Antibacterial properties of Punica granatum pericarp (peels) extracts (hot aqueous, methanolic and ethanolic) were evaluated against E.coli, P.aeruginosa and S.aureus using agar well diffusion method. Hot aqueous, methanolic and ethanolic extracts of Punica granatum pericap show an average inhibitory zone diameter of 23.3, 22.3 and 24.5mm respectively which indicates that ethanolic extract shows best result having ZOI greater than that of the standard antibiotic Tetracycline (20.1mm). Ehanolic extract of Punica Granatum has lowest MIC of 1.45 μg/ml showing that it is most effective as compared to MICs of other extracts.

Antibacterial property of locally produced hydroxyapatite

Use of synthetic hydroxyapatite (HA) in biomedical applications is well warranted. It has shown to have an excellent biocompatibility in human tooth and bones. Additionally it has been documented to possess antibacterial potentials. The present study was conducted to assess the presence of any such potential in locally produced (HA) using Streptococcus mutans, a common pathogen in the oral cavity. The study was carried out using 50, 100, 150, 200, 300, 400 and 800 mg/ml concentration of HA. The antibacterial property of HA was assessed using Miles and Misra method. Our studies showed that bacterial growth inhibitions of S. mutans occurred from 50 mg/ml, and complete inhibition was perceived at concentrations at 200mg/ml of HA. The antibacterial property HA should be used to good advantage as a bioactive biomaterial in dental and maxillofacial applications.