Background: Escherichia coli O157:H7 is one of the most important agents causing intestinal diseases. It is transmitted usually by contaminated food and particularly meat beef. Since chemically synthesized drugs have been shown to have undesirable side effects, in recent years, it is recommended to use natural materials for controlling and treatment of different kinds of infection. Therefore, the aim of this study was to compare the antimicrobial effects of the ethanolic and aqueous extracts of Scrophularia striata on Escherichia coli O157:H7. Methods: In this experimental study, ethanolic and aqueous extracts of Scrophularia striata were collected and their antibacterial activities on Ecoli O157:H7 were tested using the agar-diffusion method. Subsequently, using macro-dilution method, both minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the extract were tested against the bacterium. Amikacin (30µg) was used as an antimicrobial reference. Results: It was shown that the growth of Ecoli O157:H7 in-vitro was inhibited by the ethanolic extract of Scrophularia striata in both the agar-diffusion and macro-dilution methods. However, its aqueous extract was not effective against the bacterium. The amount of MIC and MBC of the extract were 90 and 100 mg/ml, respectively. Conclusion: The results showed that Scrophularia striata has antibacterial effects on Ecoli O157:H7. Thus, more investigation need to be done for the purification, identification, and quantification of active components presented in the ethanolic extract of Scrophularia striata.

The outbreak of Escherichia coli (E. coli) O157: H7 has been confirmed in human specimens in the spring of 1396 in one of the universities of Yazd. This study was designed to determine the source of infection. This is a case-control study in which 80 patients and 80 healthy students were examined. The formal validity and content of the questionnaire used were confirmed by the experts and the outbreak team. For data analysis, binary logistic regression and odds ratios with 95% confidence intervals were by SPSS-19 software. In this study, cantaloupe syrup with an odds ratio of 47. 37 had the highest factor in the incidence of disease. In the next stage, dinner and rice dinner with a chance ratio of 4. 25 and 3. 12 respectively, remained significant in the model. Due to the high chance of cantaloupe syrup in this study and the available records such as laboratory confirmation of the presence of E. coli O157: H7 in human samples and the report of the outbreak team on the preparation of cantaloupe syrup using a sitting meat grinder and also confirm similar studies in Possibility of presence E. coli in raw foods such as meat, it can be concluded that the source of this outbreak was cantaloupe syrup contaminated with E. coli O157: H7 via meat grinder.

Background: Infection with Escherichia coli O157:H7 rarely leads to bloody diarrhea and causes hemolytic uremic syndrome with renal failure that can be deadly dangerous. Intimin, translocated Intimin receptor (Tir), and enterohemorrhagic E. coli (EHEC) secreted protein A (EspA) proteins are the virulence factors expressed by locus of enterocyte effacement locus of EHEC. This bacterium needs EspA as a conduit for Tir delivery into the host cell and the surface arrayed Intimin, which docks the bacterium to the translocated Tir.Methods: Here we used triplet synthetic gene (eit) which was designed from three genes: espA coding EspA 120 lacking 36 amino acids from the N-terminal of the protein, eae coding Intimin constructed of 282 amino acids from the C-terminal and tir coding Tir 103, residues 258-361 which interacts with Intimin. The multimeric gene was cloned in two eukaryotic vectors pAAV-multiple cloning site-green fluorescent protein and pCI-neo. The pAAV was used for gene expression assay in cell line 293T and pCI-neo-EIT (EspA, Intimin, Tir) was used as DNA vaccine in mice. Test groups were injected intramuscularly with pCI-neo-EIT four times and mice control group was injected under the same conditions with PBS or pCI-neo vector.Results: The titration of serums showed that BALB/c mice were successfully immunized with DNA vaccine compared to control groups and also they were protected against challenges of live oral using E. coli O157:H7. Conclusion: The results suggest that the DNA vaccine could induce protective immunity either alone or in combination with purified antigens to reduce EHEC infection.

Background & Aims: Escherichia coli O: H7 is a zoonotic pathogen and has been found as an important foodborne and waterborne microorganism. The objective of this study was to investigate the antimicrobial properties of Zataria multiflora boiss. essential oils nanoemulsion on Escherichia Coli O157: H7 in pasteurized milk and in vitro.Materials & Methods: The essential oil’s nano-emulsion was prepared by inversion phase and its particle size distribution was analyzed by dynamic light scattering method. Nano-emulsion’s antimicrobial properties in BHI and pasteurized milk (1.5 and 3.2 % fat) were investigated by different methods such as agar diffusion, vapor phase diffusion, Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration, (MBC) and microbial inactivation curve after 0, 15, 30, 45, and 60 min.Results: The average droplet size was 66.5 nm. The diameter of inhibition zone in agar diffusion method was 8.74±0.4 mm, and in the vapor phase diffusion zone was not formed measurable. And MIC and MBC were 2500 mL/ml. Effects of three nanoemulsion dilution 0.1, 0.01, 0.001 on microbial inactivation in BHI broth showed that in 0.1 and 0.01 dilution after 1 hour, 6 log reduction can be observed in microbial population. In pasteurized milk with 1.5% fat, in the dilutions mentioned above, decreased by approximately 3.5 log was observed in the growth of bacteria. In pasteurized milk containing 3.2% fat, about 2.5 log reduction in microbial population for all three dilutions.Conclusion: According to the results obtained in this study, we concluded that by optimizing this method, this nanoemulsion can be used to adequately control microbial pathogens.

Enterohemorrhagic Escherichia coli O157: H7 is one of the most important causes of bloody diarrhea. This bacterium is able to make bloody diarrhea or Hemorrhagic Colitis (HC) through verotoxin or shigatoxin production, and in acute forms it may lead to Hemolytic Uremic Syndrome (HUS) or Thrombotic Thrombocytopenic Purpurea (TTP). Contamination with E. coli O157:H7 usually happens after consumption of animal products especially undercooked meats. The most important reservoir of this bacterium is beef and consumption of undercooked ground beef, especially in children younger than 10 years old, is the most common reason of food infection by this bacterium. Two important biochemical characteristics for detection of E. coli O157: H7 are lack of sorbitol fermentation and absence of glucuronidase. In order to control food infection with this bacterium, foods must be cooked thoroughly until reaching the temperature of at least 68.3°C, in the center.