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Aims: Foodborne infections caused by bacteria, including Salmonella enteritidis, Shigella flexneri, and Escherichia coli O157:H7 are one of the most common diseases among poultry and humans. The purpose of this study was the simultaneous and rapid detection of important microorganisms found in fecal samples of poultry and poultry workers.
Materials & Methods: A total of 144 fecal samples were taken from poultry and poultry farms workers. Fecal swabs were cultured on specific media, and biochemical tests were performed for further confirmation of bacterial isolates. Moreover, genomic DNA of fecal swabs was extracted for molecular identification of S. enteritidis, E. coli O157: H7, and S. flexneri species using multiplex-PCR technique.
Findings: According to the multiplex-PCR technique results, 16.7, 13.9, and 9.5% of the poultry samples were positive for the presence of S. enteritidis, E. coli O157: H7, and S. flexneri species, respectively; whereas culture method results showed the corresponding prevalence rates of 18.1, 15.2, and 12.5% for the above species. Moreover, regarding the samples collected from the poultry farms workers, multiplex PCR showed the prevalence rates of 6.9, 12.5, and 4.2% for S. enteritidis, E. coli O157: H7 , and S. flexneri species, respectively; whereas culture method showed the corresponding prevalence rates of 8.3, 13.9, and 13.9% for the above species.
Conclusion: In the current study, the sensitivity and specificity of multiplex-PCR in detecting S. enteritidis, E. coli O157: H7, and S. flexneri species were 74 and 100% for samples taken from the poultry farms workers, and 82.2 and 100% for samples taken from the poultry, respectively, suggesting the possibility of using a designed multiplex-PCR method for rapid detection of infectious agents in poultry farms.

 

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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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Objective: Shigellosis is one of the most common causes of morbidity and mortality in children with diarrhea in developing countries. It is essential to assess the antibiotic resistance patterns of these bacteria. ipaH gene is one of the virulence factors which can be used for detection of Shigella spp. Materials and Methods: Total of 100 isolates of Shigella were collected from different provinces of Iran. This isolates were characterized by biochemical tests and serological tests using polyclonal antisera for 4 species of S. dysenteriae, S. sonnei, S. boydii and S. flexneri. Antibiotic susceptibility assay for 14 different antibiotics was carried out using agar disc diffusion method. Presence of ipaH gene was investigated by PCR using specific primers. Results: From the results of this study the Shigella isolates were classified as follows: 36 (%73) Shigella sonnei, 9(%18) Shigella flexneri, 3(%5) Shigella boydii, 2(%4) Shigella dysenteriae. Approximately %50 of the Shigella isolates were resistant to Tetracycline and Cotrimoxazole. Shigella sonnei showed more resistance than other serotypes against the studied antibiotics. PCR assays showed that all isolates harbored ipaH gene. Conclusion: The results showed that prevalence of Shigella sonnei is higher than other serotypes. The isolates showed high sensitivity to third generation cephalosporines and aminoglycosides. PCR detection of ipaH gene as a reliable marker for identification of Shigella species could be recommended.

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One of the problems with the consumption of fresh vegetables is the possibility of contamination with pathogenic bacteria. Washing fresh vegetables plays an important role in reducing the microbial population and increasing the safety of these products. Electrolyzed water has been considered as a new disinfectant in recent years. It is antiseptic, inexpensive and safe that affects different species of bacteria, fungi and viruses. In this study, the use of various types of washing water has been studied on the reduction of Shigella Flexneri population in lettuce. Types of water used include drinking water, acidified drinking water, chlorinated deionized water with chlorine concentrations of 50 and 25 mg / L, neutralized electrolyzed water, acidified electrolyzed water with a chlorine concentration of 50 and 25 mg / L were studied at different washing times (60 and 180 seconds) and different washing temperatures (4 and 25 °C). The results of this study showed that electrolysis of water had the most efficiency in reducing the microbial load of lettuce (72%) and the acidification of electrolyzed water increased its disinfection efficiency (75%). In addition, the study of lettuce microbial population during 1 to 4 days showed that the growth rate of microbial growth in lettuce samples was slower than other washing methods.