Showing 8 results for Concentration
R Abiri, Mb Majnooni, P Malek Khattabi, H Adibi,
Volume 3, Issue 1 (4-2009)
Abstract
Abstract Background and objectives: Infectious diseases are the leading cause of mortality in the world. With the increase of Microbial resistance to chemical antibiotics and low side effects of medicinal herbs, it has become of great importance to use herbs as a source of antimicrobial compounds. Material and Methods: In this study, the extract of Trigonella foenum leaf and seed was prepared using 70% ethanol. Minimum Inhibitory Concentrations (MIC) and antimicrobial Sensitivity were determined using microdilution broth and disk diffusion method, respectively. The Results were compared with Gentamicin, Ciprofloxacin and Fluconasole. The tested strains were: clinical strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Enterococcus faecium, Candida albicans and two standard strains of Staphylococcus aureus and Pseudomonas aeruginosa. Results: The least MIC of the leaf extract against the standard strain of S. S. aureus, E. faecium and clinical S. aureus is 64 μg/ml and for seed extract against E. faecium and Standard S. S. aureus is also 64 μg/ml. The largest diameter of inhibitory zone caused by leaf extract on Standard S. S. aureus is 23mm, and for seed against E. faecium is 18 mm. Conclusion: Because of antimicrobial effects of leaf and seed extract of Trigonella foenum, these extracts can be used as anti microbial compounds in pharmaceutical and food industries. Therefore, the isolation, identification and purification of the antimicrobial compounds of the extracts are recommended. Key words: Trigonella foenum, Antimicrobial effects, Minimum inhibitory concentration.
Khoshdel Rad N, Mashayekhi F, Mirzajani E,
Volume 6, Issue 1 (4-2012)
Abstract
Abstract Background and objectives: C-Met is a proto-oncogene that encodes a protein known as hepatocyte growth factor receptor (HGFR). The HGF receptor possesses tyrosine -kinase activity and it is essential for embryonic development, wound healing and cancer. Many proteins are proteolytically released from the surface by a process known as ectodomain shedding. Shedding occurs under normal physiologic conditions and can be increased in certain pathologies. C-Met can be seen among many receptors for which ectodomain shedding has been shown. The aim of this study was to determine the concentration of soluble c-Met in the cerebrospinal fluid (CSF) and serum samples of patients with viral and bacterial meningitis. Material and Methods: in this study, 75 CSF and serum samples of patients with bacterial meningitis, 71 with viral meningitis and 82 normal controls were investigated. The soluble c-Met concentration was determined by enzyme linked immunosorbent assay (ELISA). Result: the amount of soluble c-met in CSF of patients with bacterial meningitis ( 83.91±5.50), viral meningitis ( 80.41±4.71) and control group ( 22.66±3.39) are compared with that in serum of patients with bacterial meningitis ( 561.58±25.87), viral meningitis ( 550.50 ±34.34) and control group ( 256.25±18.55). There is significant increase in the CSF and serum’s soluble c-Met expression in the patients with meningitis, in comparison with control group. Conclusion: The data presented here indicate that soluble c-Met is a constant component of human serum and CSF, but it can not be used for differentiating bacterial meningitis from viral meningitis. Key words: Soluble c-Met, concentration, cerebrospinal fluid, serum, meningitis
Shaghayegh Nikpour Moghadam , Shokoufeh Nikpour Moghadam ,
Volume 10, Issue 1 (1-2016)
Abstract
Abstract
Background and Objective: Enterococci are relatively nonvirulent bacteria that rarely cause disease. Antimicrobial treatment of Enterococci is often challenging due to their antibiotic resistance. This study aimed to investigate the antibacterial activity of aqueous extract of garlic against Enterococcal isolates.
Methods: In this descriptive study, 120 Enterococcus isolates including 70 multidrug-resistant isolates were collected from hospitals of Babol, Iran. Isolates’ susceptibility to different antibiotics and the antibacterial activity of garlic extract were assessed using methods of minimum inhibitory concentration (MIC) measurement. The experiments were performed according to the Clinical & Laboratory Standards Institute guidelines, using Tryptic soy broth medium and disc diffusion method.
Results: Among the 120 Enterococcal isolates, 95 (79.2%) and 25 isolates (20.8%) were E. faecalis and E. faecium, respectively. Of the all Enterococcal isolates, the highest resistance was to erythromycin (95.8%), tetracycline (88.3%) and ampicillin (65.8%). While, the minimal level of resistance was to chloramphenicol (6.8%), vancomycin (20%) and ciprofloxacin (25%). Also, 53.3% of Enterococcal isolates showed simultaneous resistance to at least three antibiotics (tetracycline, erythromycin and ampicillin). Such resistance in E. faecium isolates was higher compared to E.faecalis (68% vs. 55.7%). The range of antibacterial activity of garlic extract against isolated Enterococci was determined by growth inhibition zone of 16.8 ± 1.8 mm and MIC of between 4 to 32 mg/ml.
Conclusion: This study indicates the clear anti-enterococcal effect of aqueous extract of garlic and confirms the use of garlic in treatments by medicinal plants.
Abdollah Ardebili , Malihe Talebi , Abdolaziz Rastegar Lari ,
Volume 10, Issue 1 (1-2016)
Abstract
Abstract
Background and Objective: Due to the continuous increase of multidrug-resistant Acinetobacter baumannii strains around the world, decision making for an effective treatment of infections caused by this organism depends on the results of antimicrobial susceptibility tests. In this study, the validity of disk diffusion and E-test methods was assessed by their comparison with the reference method of microbroth dilution for three antibiotics of tetracycline, doxycycline and minocycline.
Methods: Total of 68 A. baumannii isolates were obtained from patients hospitalized in the burn center of Shahid Motahari Hospital in Tehran, Iran. Susceptibility of the Acinetobacter isolates was evaluated using the disk diffusion, E-test and microbroth dilution methods, according to the guidelines of Clinical and Laboratory Standards Institute.
Results: Among the isolates, 82.3% were tetracycline-resistant (with minimum inhibitory concentration 50 (MIC50) and MIC90 of 32 and more than 32 µg/ml, respectively and 41.2% were doxycycline-resistant (with MIC50 and MIC90 of 4 and more than 32 µg/ml, respectively). Minocycline, with resistance of up to 13.3% (MIC50 and MIC90 of 1 and 8 µg/ml, respectively) showed the highest antimicrobial activity against the A. baumannii isolates. Antimicrobial susceptibility of bacteria was different depending on the type of methods used. No very major error was observed in any of the methods of susceptibility testing. Overall, the level of major and minor errors in the E-test was lower than the disk diffusion method.
Conclusion: The results of this study indicate that minocycline has notably high antimicrobial activity against A. baumannii compared to other antibiotics of the tetracycline group.
Shima Kazemi , Monir Doudi , Gholm Reza Amiri ,
Volume 11, Issue 6 (11-2017)
Abstract
ABSTRACT
Background and Objectives: Development of ecofriendly processes for the synthesis of metal nanoparticles is of great importance in the field of nanotechnology. Microorganisms such as bacteria could be suitable candidates for bioproduction of nanoparticles due to their simplicity and high compatibility with the environment. The aim of this study was to use bacteria isolates from the effluent of wastewater treatment plants to produce silver nanoparticles.
Methods: For identifying silver-resistant microorganisms, we used the agar diffusion method using PHG II medium containing 0.5 mM silver to determine minimum inhibitory concentration. Bacterial identification was done with biochemical testing and polymerase chain reaction (colony PCR). Finally, silver nanoparticles were produced in the desired bacteria, and the properties of these nanoparticles were studied.
Results: We found five silver-resistant bacteria among which Stenotrophomonas maltophilia strain MS8 showed the highest resistance (MIC= 6 mM). The bacterium was able to synthesize silver nanoparticles in spherical shapes. The results obtained from visual observations using UV-VIS, TEM and XRD showed that the bacterium was able to reduce silver ions into silver nanoparticles with maximum size of 20 nm.
Conclusion: Based on our findings, this bacterium could be useful for biosynthesis of silver nanoparticles.
KEYWORDS: Bacteria, Biosynthesis, Minimum Inhibitory Concentration.
Azizollah Ebrahimi, Younes Daryalal, Mohamadreza Mahzounieh, Sharareh Lotfalian,
Volume 12, Issue 4 (7-2018)
Abstract
ABSTRACT
Background and Objectives: Silver nanoparticles (AgNPs) have physical and surface properties that could threaten human and environmental health. AgNPs are classified as ‘very toxic’ to eukaryotic organisms and are less toxic to bacteria. The aim of the present study was to study the effects of different sub-minimum inhibitory concentrations (MICs) of AgNPs on some virulence factors of Staphylococcus aureus as a pathogenic bacterial model.
Methods: Tube double serial dilution method was used to determine MIC of AgNPs against standard strain and ten field isolates of S. aureus. Tube cultures of isolates in LB broth were supplemented with different concentrations of AgNPs and were incubated at 37 °C with constant shaking under aerobic conditions. Samples from each tube were streaked on blood agar plates and assay for hemolysins, coagulase and DNase production were performed.
Results: The MIC of AgNPs against all examined isolates was determined as 50 µg/mL. The results showed that 1/2, 1/4 and 1/8 MIC of AgNPs had no negative effect on DNase and coagulase production but inhibited alpha- and beta-hemolysin production in most isolates (64-91%). In addition, production of delta-hemolysin was inhibited by 1/2 MIC of AgNPs.
Conclusion: The effects of sub-MIC of AgNPs on bacterial growth appear at 4-8 hours post-exposure and then the bacteria follow a normal growth trend. This toxic effect may affect ecosystems species.
Keywords: Silver particles, Minimum inhibitory concentration, Virulence factors, Staphylococcus aureus.
Fereshteh Keyghobadi, Nader Bahramifar, Elahe Gharekhani, Seyyedeh Marzieh Kia,
Volume 13, Issue 5 (9-2019)
Abstract
ABSTRACT
Background and Objectives: In this study, nanosilica modified with HS-SiO2 thiol groups was utilized as adsorbent for solid phase extraction, as a fast and reliable method of preconcentration and separation of very small quantities of selenium ions from water and blood samples.
Methods: The samples included four natural water samples and one biological sample (blood serum) prepared in volumes of 25, 100, 200, 300, 400 and 500 ml. The samples were analyzed by solid phase microextraction, using thiolated-nanosilica (as adsorbent), ultraviolet-visible spectrophotometry and atomic absorption spectroscopy.
Results: Optimized conditions for preconcentration of a 25 ml 0.2 mg/l selenium solution were pH 5, 40 mg of adsorbent, sample-adsorbent mixing time of 15 minutes and 5 ml of 2N sulfuric acid as detergent. The volume limit and concentration factor were 400 and 80, respectively. Limit of detection and relative standard deviation of the method were 0.46 μg/l and 0.9%, respectively.
Conclusion: This study is the first to successfully utilize thiolated nanosilica for measuring low selenium levels. Thiolation of the absorbent increases selenium adsorption by thiolated-silica compared to SiO2.
Keywords: Solid phase extraction, Selenium, Preconcentration, Nano, UV-visible spectrophotometry.
Azizollah Ebrahimi, Soheila Rabiaee, Sharareh Lotfalian, Saied Habibian,
Volume 14, Issue 4 (7-2020)
Abstract
ABSTRACT
Background and objectives: Clove (Syzygium aromaticum) essential oil is a food additive with proven antimicrobial and antioxidant properties. Thus, it may be a good candidate for controlling foodborne pathogens, such as Staphylococcus aureus. The aim of the present study was to evaluate effects of sub–minimum inhibitory concentrations (MICs) of clove oil on some virulence factors of S. aureus.
Methods: The standard strain and 12 field isolates of S. aureus were obtained from our microbial collections. The broth tube dilution method was used to determine the MIC of clove oil against the isolates. Sterile 96-well flat bottom polystyrene microtiter plates were used for planktonic growth and biofilm formation assays. Slide coagulase test was used for assaying effect of clove oil on clumping factor production. Production of α- and β-hemolysins was assessed by culture on 5% bovine blood agar.
Results: The results showed that sub-MIC concentrations of clove oil inhibited α- and β-hemolysins and biofilm production and planktonic growth of the examined isolates. However, clumping factor was not affected by sub-MIC concentrations of clove oil.
Conclusion: Our results indicate the favorable inhibitory effects of sub-MIC concentrations of clove oil against growth and biofilm and hemolysins production of S. aureus isolates.
