جستجوی مقالات مرتبط با کلیدواژه « Zone Of Inhibition » در نشریات گروه « پزشکی »

Milk is a dairy product which is susceptible to contamination by pathogenic and spoilage microorganisms. One way to control the growth of pathogenic bacteria is to use preservatives and antimicrobial compounds. Due to the general concerns about the side effects of chemical preservatives, there is a tendency to consume products that use natural preservatives. Natural products provide unlimited opportunities for novel and suitable additives. The main objective of this study was to evaluate the antioxidant and antimicrobial activities of hydro-ethanolic extract of rosemary (Rosmarinus officinalis L.) against some gram positive (Staphylococcus aureus and Listeria innocua) and gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and the next stage was to investigate the impact of hydro-ethanolic extract of this plant at 0.25, 0.5 and 0.75% (w/w) concentrations on the shelf life of pasteurized milk.

The present experimental study was conducted in 2022 at Nahavand Higher Education Complex. The total phenolic content of the extract was measured by Folin-ciocalteau method. Antioxidant activity of different concentration of extract were assessed by diphenyl picrylhydrazyl radical-scavenging activity and compared with synthetic antioxidant butylated hydroxyl anisole (BHA). Antibacterial effects of resemary on pathogenic bacteria was determined by well diffusion agar, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods. Experimental data were analyzed using ANOVA by the SPSS version 20 software and mean comparison were done using Duncan's multiple range test.

The phenolic content of hydro-ethanolic extract weas 96.47±0.35 mg galic acid/g extract. Hydro-ethanolic extract of rosemary had the greatest effect on Staphylococcus aureus. The MIC of rosemary ethanolic extract ranged from 12.5 to 50 mg/ml, depending on the type of bacteria (gram positive or gram negative). Also, the treatments of pasteurized milk with 0.5%, acceptable sensory properties had a significantly lower total microbial count and longer shelf life compared to the control sample.

Therefore, considering that the hydro-ethanolic extract of rosemary had a significant effect on preventing the growth of pathogenic and spoilage microorganisms, as a result, this extract can be used as a natural antibiotic in milk.

Dental caries is a major health problem nowadays. polyphenolic compounds of tea can exert its anti-cariogenic effects by affecting the cariogenic Streptococcus Mutans bacteria. The aim of this study was to investigate the antimicrobial effect of ethanolic, methanolic and aqueous extracts of green tea in comparison with chlorhexidine on Iranian strain of this bacteria.

10 g of green tea powder was dissolved in 100 mg of ethanol, methanol and aqueous solvents separately. After one week, the obtained solutions were filtered and 100mg / ml solution was extracted. to evaluate the diameter of inhibition, zone The Swabs impregnated with suspension scrubbed on culture medium. the extracts were injected onto special paper discs and the impregnated disks were placed on the bacterial culture media, plates were kept in the incubator for 24 hours at 37 °C and then the diameter of inhibition zones was calculated. Using Muller Hinton Broth, herbal extracts were made at concentrations 1:2 (50 mg/ml) and 1:4 (25 mg/ml) and 1:8 (12.5 mg/ml) and 1:16 (6.25 mg/ml) and 1:32 (3.125 mg/ml). Then, 100 μl microbial suspensions made by standard McFarland 0.5 were transferred to all test tube. The test tubes were placed in an incubator at 37°C for 24 hours. After 1 day, contents of all test tubes were separately cultured on Muller Hinton Broth medium. The culture media were incubated at 37°C for 1 day. The results were evaluated in the form of growth or non-growth of bacterial colonies on culture media and MBC and MIC were determined. ANOVA and Post hoc test was used for statistical analyze with SPSS Software.

Experimental results after three iterations showed mean values of 16.16, 16.66, 12.5 and 17.5 mm for diameter of the inhibition zone of ethanolic, methanolic and aqueous extracts and chlorhexidine 0.2%, as control. Also, at the significant level of 0.05, there was no significant difference between the diameter of the inhibition zone of ethanol, methanol and chlorhexidine extracts. (p>0.05)The Aqueous Extract Showed Significant difference with other Extracts. MBC Reported 12.5mg/ml for Ethanolic and 50mg/ml for two other extracts. MIC Reported 6.25mg/ml for ethanolic and 25mg/ml for two other extracts.

The results showed that the antimicrobial effects of ethanolic and methanolic extract of Iranian green tea are higher than aqueous extract and there is no significant difference between these two extracts with Chlorohexidine.

This laboratory experiment was aimed of to investigate the antibacterial effect of Polypropylenimine-G2 (PPI-G2) and Polyamidoamine-G4 (PAMAM-G4) dendrimers on Klebsiella oxytoca, Pseudomonas aeruginosa and Proteus mirabilis. Different concentrations of PPI-G2 and PAMAM-G4 dendrimers were inoculated onto Blank disks and were placed in Mueller-Hinton agar media. Zone of inhibition was investigated by bacterial inoculation according to the McFarland standard 0.5. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PPI-G2 and PAMAM-G4 dendrimers were determined by Micro-dilution method in nutrient broth culture. Zone of inhibition in concentration 500 μg/ml of PPI-G2 dendrimers for Klebsiella oxytoca, Proteus mirabilis and Pseudomonas aeruginosa were 25, 15 and 20mm, respectively. Zone of inhibition in concentration 500 μg/ml of PAMAM-G4 dendrimers for Klebsiella oxytoca, Proteus mirabilis and Pseudomonas aeruginosa were 20, 18 and 0mm, respectively. The MIC of PPI-G2 dendrimer for Klebsiella oxytoca and for Pseudomonas aeruginosa were 5 μg/ml. Also, the MIC of PPI-G2 dendrimer for Proteus mirabilis was 50 μg/ml. The MBC of PPI-G2 dendrimer for Klebsiella oxytoca was 50 μg/ml and it was 500 μg/ml for Proteus mirabilis and Pseudomonas aeruginosa. The MIC of PAMAM-G4 dendrimer attributed to Klebsiella oxytoca and Proteus mirabilis were reported 500 and 1250 μg/ml, respectively. The MBC of PAMAM-G4 dendrimer belonged to Klebsiella oxytoca and Proteus mirabilis were 1250 and 2500 μg/ml, respectively. According to the results, PPI-G2 dendrimers can eliminate Pseudomonas aeruginosa, Klebsiella oxytoca and Proteus mirabilis effectively but PAMAM-G4 only has antibacterial effect against Klebsiella oxytoca and Proteus mirabilis. Also the antibacterial activity of PPI-G2 dendrimer is obviously better than those of PAMAM-G4. However, using dendrimers can be considered as a new approach for drinking water disinfection but it requires further wide range studies.

This study aimed to examine the antibacterial effect of Polyamidoamine-G4 dendrimer on Escherichia coli, Enterobacter cloacae, Bacillus subtilis and Staphylococcus aureus. In this experimental study, the antibacterial effects of Polyamidoamine-G4 dendrimer were studied by disc diffusion and micro-dilution method. Different concentrations of Polyamidoamine-G4 inoculated onto blank disks and were placed in Mueller-Hinton agar media. Zone of inhibition was investigated by bacterial inoculation according to the McFarland standard 0.5. Minimum inhibitory concentration and minimum bactericidal concentration of Polyamidoamine-G4 dendrimer were determined by micro-dilution method in nutrient broth culture. Zone of inhibition in concentration 500 μg/ml of Polyamidoamine-G4 dendrimers for Escherichia coli, Enterobacter cloacae, Bacillus subtilis and Staphylococcus aureus were 14, 0, 35 and 29mm, respectively. Concerning the Zone of inhibition in gram negative bacteria with gram positive ones was p<0/05 and had significant difference. The minimum inhibitory concentration of Polyamidoamine-G4 dendrimer for Escherichia coli, Bacillus subtilis and Staphylococcus aureus were 1250, 2.5, and 1 μg/ml, respectively. The minimum bactericidal concentration of Polyamidoamine-G4 dendrimer belonged to Escherichia coli, Bacillus subtilis and Staphylococcus aureus were 2500, 5 and 5 μg/ml, respectively. Polyamidoamine-G4 dendrimer had not bacteriostatic and bactericidal effects on Enterobacter cloacae. According to the results, Polyamidoamine-G4 dendrimer can eliminate Escherichia coli, Staphylococcus aureus and Bacillus subtilis effectively. It is suggested in the rest of this study that the probable toxicity of nanostructured compounds examined in drinking water and, economic studies is done for synthesis and their applications in case of prevention of using.

Backgrounds and Dendrimers are a new class of synthetic macromolecules, which have many applications in medical sciences. This study was carried out with the purpose of investigating the antibacterial effect of polypropylenimine-G2 (PPI-G2) dendrimer on some bacterial species. In this study, the antibacterial effects of PPI-G2 dendrimer were studied by disk diffusion and microdilution method. PPI-G2 dendrimer in concentrations of 0.5, 5, 50, and 500µg/ml were inoculated onto blank disks and placed in Mueller-Hinton agar media. Zone of inhibition was investigated by bacterial inoculation according to the McFarland standard 0.5. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PPI-G2 dendrimer in the concentrations of 0.05, 0.5, 5, 50, and 500µg/ml, were determined using microdilution method in nutrient broth media. In this study, antibacterial activity of dendrimer increased with increasing their concentration in the disk. Zone of inhibition in the concentration of 500μg/ml for E. coli, Enterobacter cloacae, Bacillus subtilis, and Staphylococcus aurous were 19, 20, 25, and 21mm, respectively. The MIC for Enterobacter cloacae, Bacillus subtilis, and Staphylococcus aurous was 5μg/ml and for E. coli was 500μg/ml. In addition, the MBC for Bacillus subtilis and Staphylococcus aurous was 50μg/ml and for E. coli and Enterobacter cloacae was 500μg/ml. The findings of this study showed that PPI-G2 dendrimer has antibacterial effects. However, use of the dendrimer for drinking water disinfection requires further and wider studies.