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Comparing novel approaches for the rapid and specific detection of pathogenic Escherichia coli O157:H7 in food samples

Sietsema, E. (2016) Comparing novel approaches for the rapid and specific detection of pathogenic Escherichia coli O157:H7 in food samples. Bachelor's Thesis, Biology.

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Abstract

In this review, a comparison has been made between conventional techniques and novel techniques for the detection of Escherichia coli O157:H7 in food samples. Food born- illnesses caused by E. coli O157:H7 is formed as a main global problem. Because the ingestion of a few shiga-like toxin producing E. coli O157:H7 in food samples can induce diarrheal diseases and person-to-person spread occurs, rapid detection of this food-borne pathogen is required to prevent epidemical spread of diarrheal diseases. An insight in the E. coli O157:H7 pathogenic mechanism has been given to look for possible targets to detect E. coli O157:H7 like Stx-1 and Stx-2. Although Stx-1 is mainly used as a target to detect E. coli O157:H7, Stx-2 seems to be a more promising target. Conventional used methods are described and compared to see which is more rapid and specific for the detection of E. coli O157:H7 in food samples. At first, culturing methods are shown to be slow and unspecific, because these techniques need enrichment steps to grow bacteria. Secondly, PCR techniques can detect stx1 and stx2 in 103 CFU per PCR assay, but this number is still too low for the detection in food samples. Furthermore, PCR assays are time consuming due to necessarily enrichment steps. In contrast, immuno-based conventional methods, like latex agglutination test, Sandwich ELISA and immune magnetic separation are more specific to detect E. coli O157:H7 in food samples. However these techniques still consume a lot of time and use of antibodies are rather expensive. To reduce costs in immuno-based methods, egg yolk produced Ig-Y is seen as an inexpensive alternative. Therefore it is of importance to further clarify and compare new approaches with conventional methods for a more rapid and specific detection of food-borne E. coli O157:H7 with immune-based methods. Firstly, nanoporous membrane-based impedimetric immunosensor (NMBI) is shown to be a promising new technique to detect E. coli O157:H7 with a detection limit of 83.7 CFU/ml in less than 1 hour. Secondly, surface plasmon resonance (SPR) could detect E. coli O157:H7 in 106 CU/mL in less than 2 hours. However, when using bacteriophages the detection limit was lowered to 103 CFU/mL. Thirdly, lateral flow immuno assay (LFIA) showed to be detecting E. coli O157 antigens, Stx-1 and Stx2 with a specificity of 1.14 x 103 CFU/mL in less than three hours. Because NMBI, SPR and LFIA do not need any pre-enrichment and labeling steps, these techniques are more applicable and rapid when comparing them with conventional techniques. Of these three methods, NMBI is considered as the most rapid and specific novel technique for the detection of E. coli O157:H7 in food samples. Therefore, NMBI is the best technique suitable for the rapid and specific detection of E. coli O157:H7 in food samples. Although NMBI is not as specific as some conventional used method, it still has a strong potential to be used in the field of E.coli O157:H7 detection. Nevertheless, further studies are necessarily to develop novel inexpensive E. coli O157:H7 specific antibodies to lower the detection limit of NMBI and reduce costs for the application in food safety procedures.

Item Type: Thesis (Bachelor's Thesis)
Degree programme: Biology
Thesis type: Bachelor's Thesis
Language: English
Date Deposited: 15 Feb 2018 08:13
Last Modified: 15 Feb 2018 08:13
URI: http://fse.studenttheses.ub.rug.nl/id/eprint/14133

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