Salmonella Enteritidis Research Paper

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Salmonella enteritidis (S. enteritidis) is an organism that belongs to the genus Salmonella, the species entericas, and the phylum proteobacteria (reference something here). S. enteritidis is commonly found in poultry and eggs, and is transmitted through food contaminated by fecal matter. Another closely related serovar of this species are S. enterica serovar Typhimurium, a typhoidal organism that only causes infections in humans. Many members of the Enterobacteriaceae family are part of the normal flora of the gut microbiota (Ibarra, 2009). Salmonella enteritidis cells are Gram-negative rod-shaped bacteria that range in width from 0.7 to 1.5 μm, and 2 to 5 μm in length. Salmonella enteritidis is a facultative anaerobe that is
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enteritidis from a fecal sample, enrichment and selective isolation is the best route. The preferred broth for this is either tetrathionate or selenite broth. In regards to solid media, there is a wide assortment of media to chose from, but there is four main choices used worldwide. There is SS agar, Wilson-Blair bismuth sulfite agar, Hektoen enteric medium, and Kristensen-Lester-Juergens brilliant green agar. The inoculated media is incubated overnight at 37C. To test if these colonies are Salmonella, we would expect to see small to medium sized colonies that test lactose negative and catalase positive (Minor,…show more content…
Cell wall (somatic O) antigens are antigens that are heat stable and alcohol resistant. Surface (envelope) antigens, which is common in other genera of bacteria, is not present in this serotype of Salmonella. Flagellar (H) antigens, are heat labile proteins. S. enteritidis has only one flagellar antigen, which makes it monophasic. This helps distinguish it from other Salmonella serotypes, because it’s vh_2 gene is nonfunctional (Minor, 1992).
Serotyping is done by pooling sera and using monospecific anti sera. This is used to distinguish what antigens are present on the bacteria. The antigenic formula for S. enteritidis is 1, 9,12:g,m:-. This means that S. enteritidis has O factor 1 that originates from phage conversion, as well as O factors 9 (major) and 12 (minor). It also has phase 1 flagellar antigen g and m, with no phase 2 antigen. (Minor, 1992)
Another way to test for a specific serovar is fluorescent-antibody techniques. This is done by testing for a specific salmonella serotype using specific O antiserum. If using O antiserum, fecal smears can be used for testing. If testing for flagellar (H) antigens, smears need to be prepared from cultures and not fecal smears. Fluorescent-antibody testing can test for Salmonella, but not a definite identification. This is impractical because further isolation and biochemical testing is required, but this process is useful when screening
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