S. Mahdavi, A.r. Isazadeh,
Volume 22, Issue 2 (3-2019)
Abstract
Aims: The aim of this study was investigation of contamination rate and determination of pattern of antibiotic resistance in coagulase positive Staphylococcus aureus isolated from domestic cheeses in Maragheh, Iran.
Materials and Methods: In this experimental study, 100 traditional white brine cheese samples were collected from different villages of Maragheh with the observance of aseptic principles and transferred to microbiology laboratory of Islamic Azad University, Maragheh branch. The samples were cultured in specific media and the complementary biochemical tests were done for the identification of coagulase positive Staphylococcus aureus. For molecular diagnosis of S.aureus, these isolates were identified as S.aureus with the proliferation of Thermonuclease species-specific gene (nuc) by polymerase chain reaction (PCR) method. Cheese samples were tested for pH and NaCl content. The susceptibility of all isolates to different antibiotics was evaluated by kirby-bauer’s method.
Findings: Of 100 samples taken from villages of Maragheh, 21 samples (21%) were identified as Staphylococcus aureus coagulase positive. 20 isolates were resistant to more than one antibiotic. The most resistance of isolates were to penicillin, vancomycin, and methicillin, respectively. No significant difference was shown among old and fresh samples in Staphylococcus aureus incidence (p>0.05).
Conclusion: Considering the high contamination rate of domestic cheese by coagulase positive Staphylococcus aureus in Maragheh, the production and distribution of these cheeses should be under hygienic situations. Efficient informing about the potential risk of using these products seems necessary.
N. Ghasemi, S. Falsafi, K. Amini,
Volume 23, Issue 3 (7-2020)
Abstract
Introduction: The invA gene plays a critical role in the pathogenicity of Salmonella infantis. Marine organisms, including sea cucumbers due to their effective secondary metabolites, have been identified and studied with compounds with antioxidant, anti-cancer, antibacterial and anti-inflammatory properties. The aim of this study is to determine effect of sea cucumber extraction (Holothuria leucospilota) on S. infantis invA gene expression .
Material & Methods: Poultry meat was sampled. The S. infantis strains containing invA gene were isolated. The Hexane extract was extracted from sea cucumber colon tissue. Its effects on S. infantis and its effect on gene expression were investigated by MIC and Real-time PCR, respectively.
Results: Morphological and biochemical characteristics of these bacteria were confirmed. From 450 samples, 12 S.infantis isolates were isolated. The PCR technique was used to identify the invA encoding gene. All 12 isolates have invA virulence genes. MIC was determined 256 µg/ml. The effect of sea cucumber extract on invA gene expression in S.infantis was evaluated, and the rate of change for the invA gene is estimated -1.21.
Discussion & Conclusion: According to our results, hexane extract extracted from the sea cucumber (H. leucospilota) caused reduction ofinvA gene expression in salmonella infantis. So, it can be used as a therapeutic supplement against S. infantis
Sareh Bagheri-Josheghani, Bita Bakhshi,
Volume 24, Issue 2 (2-2021)
Abstract
Introduction: Vibrio cholerae, the causative agent of cholera, has attracted a great deal of attention as one of the major causes of morbidity and mortality worldwide, especially in developing countries. In most laboratories, biochemical assays are primarily performed for possible detection of these strains, which are then followed by a PCR (polymerase chain reaction) test to verify their identity. This study aimed to optimize dot blot technique to detect Vibrio cholerae bacteria for V. cholera as an easy-to-use and beneficial method.
Methods: A dot blot hybridization test was developed in this study to identify V. cholerae isolates as well as to assess the sensitivity and specificity of this test compared whit biochemical and PCR tests routinely performed for V. cholerae screening and detection in clinical specimens.
Results: Herein, the dot blot hybridization test was optimized to detect V. cholerae. A combination of three biochemical assays and PCR test confirmed the results of dot blot hybridization test. This test was able to identify V. cholerae strains with a high sensitivity and specificity of 100%. Using the newly developed method, a set of 26 V. cholerae isolates collected from clinical samples were accurately identified.
Conclusion: This study optimized dot blot technique as a simple and useful assay that could be employed in V. cholerae monitoring programs and strategies to effectively detect V. cholerae strains in surface water and fecal specimens.
Frozan Abidkanjo, Neda Soleimani,
Volume 24, Issue 3 (7-2021)
Abstract
Helicobacter pylori is a specific pathogen of the human stomach that immunomodulatory effects of Helicobacter pylori fractions have been suggested as an immune stimulus factor in vaccine candidate design. Helicobacter pylori FlgE2 protein is part of bacterial flagellum membrane whose effects on innate immune cells have not been studied. In the present study, we aimed to assess the effect of FlgE2 on the production of nitric oxide (NO) by rat peritoneal macrophages.
Helicobacter pylori FlgE2 protein was recombinant produced. Peritoneal macrophages of mice were removed and cultured. Different concentrations of recombinant FlgE2 protein were used to stimulate macrophages and assess NO production. To detect NO, macrophage culture supernatant was removed and evaluated by reagent grease. Finally, the results were evaluated by SPSS software. The results showed that the recombinant FlgE2 protein from Helicobacter pylori increased the level of nitric oxide by increasing the concentration. At 80 μg/ml (P=0.01), the increase in nitric oxide level had the highest level of production and then was observed at 40 μg/ml, which increased significantly compared to the LPS control group. This increase was then observed at concentrations of 20 and 4 μg/ml.
According to the findings of this study, recombinant FlgE2 has a positive effect on stimulation of NO production by peritoneal macrophages. Therefore, it is suggested that recombinant FlgE2 can be proposed as an immunostimulant for vaccine candidates.
Keyvan Esmaeili Fard Barzegar, Shahin Najar-Peerayeh, Ramin Mazaheri Nezhad Fard, Bita Bakhshi,
Volume 24, Issue 3 (7-2021)
Abstract
Introduction: Enteropathogenic Escherichia coli (EPEC) strains cause a gastrointestinal disease in the developing countries. Over the years, antimicrobial resistance of EPEC have been a major issue. Bacteriophages have been a therapeutic option for bacterial infection. Our aim was to assay lytic activity of a siphophage on an EPEC strain. Materials and Method: EPEC strain ATCC 43887 was used for phage isolation using by double layer agar method. Bacteriophage morphology was visualized by transmission electron microscope. Result: a siphophage was detected by transmission electron microscope images. The phage formed small clear circular plaques. The results of lytic activity of siphophage on reference EPEC strain showed the phage could lyse the strain. Conclusion: the phage had lytic activity on reference EPEC strain. The phage belonged to siphoviridae family. It look the phage can lyse clinical EPEC strains.
Amin Sadeghi Dousari, Amin Talebi Bazmin Abadi, Hamidreza Forootanfar, Mojtaba Shakibaie,
Volume 25, Issue 1 (1-2022)
Abstract
Introduction: Today, the biosynthesis of nanoparticles (NPs) assisted by microorganisms (particularly bacteria) received increasing attention. In this study, Bacillus subtilis strain SFTS, a bismuth-reducing bacterium, was isolated from the soil of a copper mine in the South of Iran and used for biosynthesis of bismuth NPs (Bi NPs).
Materials and methods: Bacillus subtilis strain SFTS was identified by conventional identification tests and the 16S rDNA fragment amplification method. Characterizations of the bio-fabricated Bi NPs were examined using FTIR, EDS, XRD, TEM, and SEM analysis after purification of Bi NPs. In addition, the synergistic effect of biogenic Bi NPs in combination with different antibiotics was also investigated.
Results: The attained results revealed that the biosynthesized Bi NPs average size was 22.36 nm and spherical in shape. The XRD pattern showed that the biosynthesized nanoparticles consisted only of Bi4 and monoclinic crystals. Furthermore, the results of antibacterial effect of Bi NPs in combination with various antibiotics showed that the nanoparticles represented the highest synergistic effect together with imipenem and the lowest effect in combination with tetracycline against clinical strains of E. coli and K. pneumoniae. Significant difference between synergistic effect of Bi NPs with antibiotics compared to antibiotics disc alone against E. coli and K. pneumoniae strains was observed (P<0.001).
Conclusion: This study showed that Bi NPs biologically synthesized by Bacillus subtilis strain SFTS had a small size and different structure. However, finding about their antibacterial effect and related mechanism merit further investigations.
