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Salmonella - Salmonella Praveen Rao Sophia W Riccardi...

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Salmonella Praveen Rao, Sophia W. Riccardi, Danielle Birrer Seminar in Nucleic Acids-Spring 2004 Prof. Zubay
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Salmonella Overview History and Epidemiology Molecular Biology Clinical Weaponization
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Overview Salmonella is a rod- shaped, gram- negative, facultative anaerobe in the family Enterobacteriaceae
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Salmonella Taxonomy The genus Salmonella is divided into two species, S. enterica and S. bongori (CDC). Over 2000 strains are grouped into S. enterica. This species is further divided into six subgroups based on host range specificity, which also involves immunoreactivity of three surface antigens, O, H and Vi. All strains that are pathogenic to humans are in species S. enterica, subgroup 1 (also called enterica). For example, the correct taxonomic name for the organism that causes typhoid fever is Salmonella enterica ssp. enterica, serovar typhi. The simplified version: Salmonella typhi. Taxonomy has been revised several times, due to the degree of DNA similarity between genomes. For example, In the U.S., another legitimate species name for enterica is choleraesuis.
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Other Facts Bacterium of 2501 identified strains, as of 2001. Many different diseases are caused by more than 1,400 serotypes of this bacteria genus. “Salmonella” derived from Dr. Salmon, a U.S. veterinary surgeon, who discovered and isolated the strain enterica or choleraesuis from the intestine of a pig in 1885. They are ingested orally by contaminated food or water. Refrigeration prevents growth but does not kill bacteria. Heating at 57-60°C or 134-140°F has shown to be effective in killing the bacteria. Optimal growth: 37°C or 98.6°F
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Disease-associated facts “Salmonellosis”: Any of several bacterial infections caused by species of Salmonella, ranging from mild to serious infections. Two main kinds in humans: enteric fever (typhoid and paratyphoid) and gastroenteritis (non-typhoidal). The main feature for S. diseases is the Type III Secretion System, a needle-like multi-protein complex that is associated with transferring toxic proteins to host cells.
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Principal habitats in different types of Salmonella Their principal habitat is the intestinal tracts and bloodstream of humans, and in the intestinal tracts of a wide variety of animals. The WHO groups Salmonella into 3 types: - Typhoidal (enteric) Salmonella (example: S. typhi)              ٠ causes typhoid and paratyphoid fever              ٠ restricted to growth in human hosts ٠ principal habitat is in intestinal tracts and the bloodstream
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- Nontyphoidal Salmonella (example: S. enteritidis, S. typhimurium) ٠ prevalent in gastrointestinal tracts of a broad range of animals, including mammals, reptiles, birds and insects.
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