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Aims: The use of medications with plant origin covers a wide variety of maladies and constitutes an alternative way to antibiotic therapy, which seems to be no longer promising due to the widespread antibiotics resistance among the pathogenic microorganisms.
Active principles having antimicrobial activity could be extracted and purified from plants and used in developing new medications. Among several diseases which have historically scourged man, some of the gram-negative bacteria are potentially epidemic and considered as one of the most outstanding causes of diarrhea. Therefore, this study aimed to evaluate the antibacterial activity of Thymus kotschyanus extracts.
Materials & Methods: The antimicrobial effect of T.  kotschyanus  Boiss leaves extract on some gram-negative bacteria strains was assayed in vitro by the disk diffusion technique. Dried and crushed plant materials were extracted from distilled water by evaporation and distillation. Finally, the antimicrobial assays were carried out for the plant, and the results were compared with an ampicillin disk results.
Findings: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhimurium, Entrobacter cloacae, Proteus mirabilis, and Shigella dysenteriae were apparently killed by the extract, as judged by the presence of growth inhibition halos in the assays.
The results of minimum inhibitory concentrations (MICs) showed that E. coli and E. cloacae strains were better inhibited by the extract.
Conclusion: The above results were similar to those from ampicillin disk, suggesting that T. kotschyanus Boiss could be used as a source of active principles against some gram-negative bacteria. Therefore, the tested Thymus extract could be considered as a valuable natural antibacterial source, which seems to be applicable in both medicine and food industry.

 

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Background: This study aimed to determine antibacterial activity of ethanolic extract of Matricaria chamomilla (chamomile) against methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant (MDR) Pseudomonas aeruginosa strains isolated from clinical specimens.
Materials & Methods: The plant samples were collected, and the flowers and leaves were separated and dried completely in the shade. After grinding, extraction was performed using the maceration method. The extracts of both flowers and leaves were dried at 37°C for 24 hrs. About 500 mg of the dried plant extract was dissolved in 10 mL of 5% dimethyl sulfoxide and sterilized by filtration through a 0.45 µm membrane filter. For the antibacterial assay, agar well diffusion and broth microdilution methods were used.
Findings: No inhibitory effect was observed for both extracts against MDR P. aeruginosa isolates in agar well diffusion method. In broth microdilution method, the leaves extract showed inhibitory effect, and its MIC and MBC were determined at 12.5 and 25 mg/mL concentrations, respectively. The flowers extract showed antibacterial activity against most MRSA isolates. The extract of leaves demonstrated inhibitory effect on 7 MRSA isolates. The MIC and MBC of flowers extract were determined at concentrations of 6.25 and 12.5 mg/mL for most MRSA isolates, while MIC and MBC of leaves extract were 12.5 and 25 mg/mL for a few MRSA isolates, respectively.
Conclusion: In this study, the ethanolic extract of chamomile leaves showed antibacterial activity against MDR P. aeruginosa isolates; meanwhile, the flowers extract showed better activity against MRSA isolates.

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Nanotechnology is a principally attractive area of research related with production of nanoparticles of variable sizes, shapes, chemical compositions and their possible application for human being benefits. Creation, manipulation and utilization of metallic nanoparticles, because of reduction of materials dimensions, affect the physical properties and results in displaying extraordinary thermal, optical and electronic properties of nonmaterial. The biological approaches to synthesis of nanoparticles are better than chemical and physical procedures because of low energy and time expenditure.
In this study the possibility of production of nano-silver particles from dried flower buds of Clove was investigated and antibacterial and anti-fungal activities of produced nanoparticles were studied by diffusion disc and well methods. The displayed UV-visible spectra, with a wavelength of 300 to 600 nm, identifies formation of silver nanoparticles, whenever the colorless initial acclimated mixture turned to brown. The centrifuged powder samples were examined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) methods. Based on the results of this study, produced silver nanoparticles were spherical in the range of 27 to 69 nm and showed effective antimicrobial activity against Bacillus subtilis, Escherichia coli, Staphylococcus aureus and Saccharomyces cerevisiae. Therefore clove can be used as a biological source for the synthesis of nanoparticles in an industrial scale with a very low cost.

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Pseudomonas tolaasii Paine and Ewingella americana Grimont are considered as devastating pathogens in mushroom cultivation. Due to the short shelf life of button mushrooms, safe methods should be used to control these pathogens to avoid any toxic residues on the products. Plant secondary metabolites are assumed as important sources for biopesticides development. The aim of this study was to screen plant species for antibacterial properties against P. tolaasii and E. americana. Antibacterial activity of aqueous extract of 17 plant species on two pathogens was investigated in vitro using the disc diffusion method at 10 and 20 mg active ingredients per disc. Then the effect of extracts possessing antibacterial activity was tested on mycelial growth of button mushroom Agaricus bisporus (Lange) using the disc diffusion method. Analysis through measuring the diameter of growth inhibition zones revealed that the extract of Hymenocrater longiflorus Benth. and the other extracts including H. longiflorus, Achillea millefolium L., Eucalyptus sp. and Teucrium polium L. had significant antibacterial activity on E. americana and P. tolaasii, respectively. However, they had no inhibitory activity on mycelial growth of A. bisporus. The efficacy of four mentioned extracts was evaluated in the control of mushroom brown blotch disease caused by P. tolaasii, in vivo. Assessment of disease severity showed that all four extracts, at tested concentrations, had some level of preventive effect on P. tolaasii with no adverse effects on A. bisporus. It is noteworthy that the strength of the A. millefolium extract at 10% did not differ significantly from the 1% household bleach in reducing the disease severity. Therefore, it is possible that some plant extracts have the power to be considered as alternatives to chemical bleaches. Moreover, findings suggest that H. longiflorus extract is a promising candidate for control of P. tolaasii and E. americana in mushroom cultivation.

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Since one of the main problems in bone tissue repair is the bacterial infections, recently the development of drug-eluting nanocomposite scaffolds for bone regenerative medicine applications has attracted significant attention. In this study Polycaprolactone (PCL)-based composite scaffolds containing 10vol% of titanium dioxide nanoparticles (~21nm), and bioactive glass particles (~6µm), were prepared without drug and also loaded by Tetracycline hydrochloride (TCH) antibiotic (0.57, 1.15 mg/mL) through solvent casting method for bone tissue engineering applications. Structural characterizations based on Scanning Electron Microscopy (SEM), and FTIR analysis were utilized to study the chemical bonds of glass/ceramic particles, and antibiotic crystals on the surface. In addition, in vitro cytotoxicity, and antibacterial analysis were performed by MTT, and Agar well-diffusion assays, respectively. In this study polymeric and composite scaffolds were fabricated with TCH clusters decorated on the surface. It was shown that the bioactive glass/PCL scaffolds loaded by 0.57 mg/mL of TCH revealed significant antibacterial effect, despite the acceptable cell viability. These scaffolds seem to be of interest as a potential candidate in drug-eluting scaffolds for bone tissue engineering applications.

 

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Infectious diseases created by strains of Antibiotic resistance Escherichia coli and Staphylococcus aureus, is increasing in many countries such as Iran. Therefore, many efforts are performing in order to find a new composition as replacement for antibiotics. In this experimental research, an antimicrobial effect of the ethanolic and aqueous extract of Hibiscus Sabdariffa was investigated on several strains of Escherichia coli and Staphylococcus aureus resistant to common clinical antibiotics.The extract of Hibiscus Sabdariffa was prepared using rotary. Twenty strains of Escherichia coli and Staphylococcus aureus were provided from Mashhad University of Medical Sciences. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using Serial Dilution Method in six concentrations onto strains of Escherichia coli and Staphylococcus aureus in broth media.The results showed that Escherichia coli was resistant to antibiotics of penicillin (75.9%), erythromycin (58.3%), tetracycline (56.9%), and cefixime (37%), and Staphylococcus aureus showed resistant to antibiotics of penicillin (83.5%), cefixime (80%), erythromycin (55.6%), and tetracycline (26.1%), respectively. Also, the ethanolic extract of Hibiscus Sabdariffa has acceptable effect on antibiotic resistant strains of Escherichia coli and Staphylococcus aureus that MIC of the Hibiscus Sabdariffa ethanolic extract was 4 and 16 mg/mL for Escherichia coli and Staphylococcus aureus, respectively.The overall, the Hibiscus Sabdariffa extract has inhibitory ability on Antibiotic resistant Escherichia coli and Staphylococcus aureus strains. So, the ethanolic and aqueous extract of Hibiscus tea can be used in in pharmaceutical industry for medical treatments with perfect study.

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This Research was to investigate the antibacterial effects of aqueous and ethanolic extracts of Aloe Vera on pathogenic bacteria such as Staphylococcus aureus (ATCC25923), Escherichia coli (ATCC25922), Listeria monocytogenes (ATCC33090) using disk diffusion and broth Microdilution methods. The results illustrated that gram-positive bacteria are more sensitive to ethanolic extract of Aloe Vera as compared with gram-negatives bacteria. This phenomenon is due to the structure and the strength of cell wall in gram-negative bacteria as well as the nature and active compounds of Aloe Vera. Ethanolic extract of Aloe Vera showed that the maximum antibacterial activity on Staphylococcus aureus and Listeria monocytogenes in whichthe minimum inhibitory concentration (MIC) was 0.132 and 0.625 mg/ml respectively. The maximum inhibition zone was observed on Staphylococcus aureus and Listeria monocytogenes with 12 and 8 mm respectively. On the other hand, aqueous extract of Aloe Vera did not show any antibacterial activity. It is supposed that antibacterial compounds such as Anthraquinone, Hydroxyanthra and Saponin had the most roles for antibacterial activity in ethanolic extract on Aloe Vera.

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        In this study, Antibacterial activity of garlic essential oil used by disk diffusion method, micro-dilution broth (minimum inhibitory concentration) and minimum bactericidal concentration (MBC) on a number of pathogenic strains (Pseudomonas aeruginosa, Escherichia coli, Listeria innocua and Staphylococcus aureus) was studied in vitro. Chemical compounds of garlic essential oil were identified by gas chromatography. The antioxidant potential, total phenol and flavonoid were determined using radical reduction capacity, Folin–Ciocalteu and aluminum trichloride colorimetric, respectively. The results showed that the minimum inhibitory concentration of garlic essential oil was 128, 128, 32 and 64 mg/ml for Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Listeria innocua respectively. By increasing the concentration of essential oil, the diameter of the inhibition zone increased. The highest inhibition zone with 31.70 ± 0.55 mmm diameter was due to Staphylococcus aureus. The results showed that gram-negative bacteria of Escherichia coli and Pseudomonas aeruginosa were the most resistant to garlic essential oil. The results of identification of the chemical compounds of garlic essential oil showed that the combination of di-allyl disulfide was 40.3% higher. Total phenol, flavonoids and antioxidant activity of garlic essential oil was 0.33 mg gallic acid in gram, 0.24 mg quercetin in grams and 80% respectively. The results of this study showed that garlic can be used as a potential source for the production of pharmaceutical compounds.

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In recent years, multiple drug resistance in human pathogenic microorganisms have developed due to indiscriminate use of commercial antimicrobial drugs commonly used in the treatment of infectious diseases. This situation forced scientists for searching new antimicrobial substances from various sources, like medicinal plants, which are the good sources of novel antimicrobial chemotherapeutic agents. In this study, the antibacterial effect of Cardin leaf was investigated. Hydroalcoholic extract of this plant was prepared at concentrations of 0.390 to 100 mg/ml and antimicrobial effect of extract were tested with disk diffusion and agar-well diffusion diffusion method against Listeria monocytogenes, Salmonella enteritidis and Pseudomonas aeruginosa strains. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the Cardin extract were investigated by dilution method. In the disk and well diffusion methods, the highest effect of extract on the bacteria was observed at concentration of 100 mg / ml, with the highest diameter of deterioration hole. Of course, the effect on gram-positive bacteria was more than gram negative. The inhibitory concentration of extract (MIC) on Listeria monocytogenes, Salmonella enteritidis and Pseudomonas aeruginosa was 12.5, 25 and 50 mg/ml and the MBC was 50, 100 and 100 mg/ml, respectively. The results showed that effect of Cardin extract on gram-positive bacteria was more than gram negative and the diameter of the non-growth halo increased with increasing concentrations of the extract.
 

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Evaluation of probiotic properties of microorganisms isolated from stressful substrates has received considerable attention. Among probiotic microorganisms, yeasts are distinguished from lactic acid bacteria due to their bigger size, better adhesion ability, and resistance to antibiotics without the possibility of transferring resistance genes. In the present study, probiotic and antifungal properties of the predominant yeast isolated from natural honey were investigated. Sequencing results of the PCR products led to the identification of Saccharomyces cerevisiae as the predominant yeast isolated from honey. Moreover, the isolate had no hemolytic activity and showed the highest sensitivity towards natamycin among the studied antimycotic agents. In addition, although the yeast isolate had no proper survival under simulated gastrointestinal conditions, it had relatively high auto-aggregation (93.86%) and cell-surface hydrophobicity (76.36%). The highest co-aggregation ability of the isolate was also observed with Gram-positive bacteria Bacillus cereus and Staphylococcus aureus, and the inhibition activity of the isolate against B. cereus was significantly (p<0.05) higher than those of the other studied food-borne bacteria. The yeast isolate also showed 32.18% antifungal effect on Aspergillus flavus. Accordingly, the predominant yeast isolated from honey has suitable capabilities for application as a protective culture in fermentation industries.