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Aims: Food safety has emerged as an important global issue with international trade and public health implications. Staphylococcus aureus is recognized as an important cause of food poisoning related to the consumption of raw, undercooked or mishandled foods worldwide. The aim of this study was to investigate the presence and the frequency of enterotoxin producing S. aureus and SE genes in meat samples collected from meat retail outlets and restaurants in Zanjan, Iran.
Materials and Methods: In this cross sectional study, from March to June 2015, a total of 90 individual meat samples were collected from meat retail outlets and restaurants in Zanjan, Iran and investigated the frequency of enterotoxin producing S. aureus and SE genes. The meat samples were immediately homogenized and cultured on Baird parker agar and subjected for confirmatory biochemical tests and molecular detection of femA, sea, seb, sec, sed and see genes.
Findings: A total of 31 (34.4%) meat samples were positive for the presence of S. aureus. The frequency of S. aureus in raw meat (23.3%) was higher than cooked meat samples (11.1%). Enterotoxin-producing capacity was determined in 18 (20.0%) out of 90 homogenized meat samples using ELISA technique. The most prevalent SE gene was sea (38.7%), followed by see (22.6%), sec (16.1%) and seb (12.9%). SE genes were not found in strains isolated from cooked meat samples.
Conclusion: Detection of enterotoxigenic S. aureus in raw meat samples shows a probable risk for public health.
 

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The effect of essential oil (EO) from Carum copticum at concentrations of 0 (control), 0.5%, 0.75% and 1% on Staphylococcus aureus growth and gene expression of enterotoxins (SE) A and C in surimi from kilka (Clupeonella cultriventris caspia) was determined during  0, 5, 10, 15 and 20 days of refrigeration storage (4 °C). The main compounds of EO were thymol (36.4%), p-cymene (31.4%) and γ-terpinen (21.73%). Minimum inhibitory concentration and maximum tolerable concentration of EO against in S. aureus in broth medium were 0.06% and 0.015%, respectively. The growth rate significantly differ between S.aureus population in control (11.31 log CFU/g) and EO-treated samples, 9.76, 7.21 and 6.06 log CFU/g in samples containing 0.5%, 0.75% and 1%, respectively. The highest inhibitory activity against gene transcription of entertoxins was observed at 1% EO; also, the inhibitory effect of EO concentrations against expression of enterotoxin C was higher than enterotoxin A., as enterotoxin A expression was 4.5 and 8.23 fold lower than control at days 5 and 20, and enterotoxin C expression, at days 5 and 20, decreased 5.11 and 8.94 fold compared to control. The results of this study showed that EO from C. copticum is an effective component in reducing bacterial growth rate and staphylococcal enterotoxins production in kilka surimi.  

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Food born intoxications are kind of current problem in human society and most of them are caused by enterotoxins of Staphylococcus aureus.. Also probiotics(Lactic acid bacteria) have been known as health and immune system modulator. In this experiment we assessed the effects of Lactobacillus acidophilus LA5 and Lactobacillus casei 10⁸cfu/ml on growth of Staphylococcus aureus 10⁵cfu/ml at 25 ^°C and 35^°C in TSB. Then samples from the co cultured and control were pour plated in  Baird parker agar and MRS agar to compute the bacterial count at 0, 8, 24, 48, 72 hours after incubation. We found that Lactobacillus acidophilus (LA5 )Lactobacillus casei  inhibited the growth of Staphylococcus aureus 29213 and comparing to controls reduced number of S. aureus cells was by 3 logs in 25 ^°C and 2 logs in 35 ^°C. enterotoxin production by S. aureus was also inhibited in both temperatures of 25 and 35 ^°C due to ELIZA rida screen test. Lactobacillus acidophilus and Lactobacillus casei inhibited the production of  entrotoxins A, C and E at 25 ^°C and A and/orC at 35 ^°C. In conclusion, the results of this study revealed the effectiveness of Lactobacillus acidophilus and Lactobacillus casei in inhibition of Staphylococcus aureus growth and enterotoxin production proposed their potential application as antibacterial in food.

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Backgrounds: Bacterial toxins are virulence factors that manipulate the functions of host cells and take over the control of main processes of living organisms. Importantly, they are non-curable, non-contagious, and non-infectious by chemotherapeutic agents and/or antibiotics. The multifactorial nature of the toxicity of bacterial toxins has made their investigation more complicated.
Methods: In this review, we investigated some biological activities, structure, and action mechanism of several bacterial toxins using data from studies published in major international databases.
Conclusion: Bacterial protein toxins are very diverse based on size, structure and mode of action. Based on the structure and the type of cell surface receptors, the mentioned toxins have activity on the cell surface (signal transmission, pore formation) or have intracellular activity. Many bacterial protein toxins have the ability to enter the cell by the endocytosis mechanism, and according to their intracellular targets, they can induce different intracellular effects, which in many cases lead to the death of the target cell. A large and interesting group of bacterial toxins are enterotoxins. The majority of toxigenic bacteria are environmental, and the digestive system is one of the most common ways of entering or encountering environmental bacteria or their toxic products through eating food. Many enteropathogenic bacteria produce enterotoxins in food, in the intestinal lumen or on the surface of the intestinal mucosa. Also, some entero-invasive bacteria penetrate the cells by inoculating some toxins into the intestinal cells. The challenge of studying bacterial toxins and enterotoxins lies in their complex nature and the need for comprehensive characterization, but the future holds promise with advancements in technology and interdisciplinary approaches to further our understanding and develop effective strategies for prevention and treatment.

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Background: Shigella and Enterohemorrhagic Escherichia coli are among the most common causes of bacterial diarrhea, and no effective vaccine candidate for these bacteria have approved yet. Due to the role of IpaD protein and Shigella enterotoxin B subunit (StxB) in Shigella and E. coli O157: H7 pathogenicity, STX1B-IpaD chimeric protein can be used as a suitable molecule to produce a recombinant vaccine candidate. This study aimed to clone, express, and purify STX1B-IpaD chimeric protein to develop an effective vaccine candidate against Shigella and E. coli O157: H7 species. Materials and Methods: IpaD gene with NdeI and BamHI restriction enzyme sites was isolated from a recombinant vector and subcloned into the pET28a -STX1B expression vector. Vector was transferred to E.coli strain Rosetta (DE3) and confirmed by PCR and restriction enzyme digestion. SDS-PAGE and western blotting were used to confirm the recombinant protein. The recombinant STX1B-IpaD protein was purified by affinity chromatography, and its concentration was measured by the Bradford method. Results: The PCR and restriction enzyme digestion showed the accuracy of the gene cloning. The protein electrophoresis showed the proper expression and correct molecular weight (27 kDa) of STX1B-IpaD. The western blot analysis confirmed the recombinant protein. The recombinant protein concentration was estimated at more than 0.3 gr/L. Conclusion: An effective method for the production of recombinant proteins is codon optimization and effective expression in heterologous hosts. After the immunogenicity in the animal model, this recombinant protein can be used as a chimeric vaccine candidate against EHEC and Shigella bacteria.

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The study aimed to investigate the frequency of enterotoxin-producing Staphylococcus aureus isolates in hamburgers and meat bites in Mashhad and the frequency of the gene. In this practical descriptive research, the number of 175 meat samples including 70 hamburger samples, 70 kebab bite samples, and 35 handmade hamburger samples in a non-repetitive and cluster sampling method, from the brand various commercial products were collected from the supply centers in Mashhad from April to June 2023. After culturing the samples in a specific medium and isolating the isolates suspected of Staphylococcus aureus, the bacteria were identified using morphological and biochemical characteristics. Then they were confirmed by using a specific primer and polymerase chain reaction (PCR). Using PCR, the frequency of enterotoxin-producing genes was detected and the antibiotic resistance of Staphylococcus aureus isolates was checked by disc diffusion method in food samples. Among the 175 meat products tested, 28 hamburger samples (16%), 12 kebab samples (7%), and 15 handmade hamburger samples (about 9%) were pathogenic bacteria. were infected with Staphylococcus aureus. Compared to kebab samples, hamburger samples showed higher contamination, and more of them were reported as Staphylococcus aureus positive. nuc gene was detected in all bacteria identified by biochemical method. The presence of the sea gene was detected in 45 samples of tested meat products (25.71% of all samples). sec and see genes were found in 4 (2.28%) and 6 (4.08%) food samples, respectively. Genes encoding used and sed were not found in any of the studied samples. In addition, many isolates showed high resistance to tetracycline, clindamycin, and oxacillin; some were resistant to more than one antibiotic. In this study, the results obtained from the SEA-F and SEA-R blast analyses revealed that the sequences had more than 98% agreement with the overlapping results.