Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.8 to 1.5 µm, lengths from 2 to 5 µm, and peritrichous flagella, (flagella that are all around the cell body). They are chemoorganotrophs, obtaining their energy from oxidation and reduction reactions using organic sources, and are facultative anaerobes. There are only two species of Salmonella; Salmonella bongori and Salmonella enterica of which there are around six subspecies and innumerable serovars. Salmonella belongs to the same family as Escherichia, which has as a species E.coli. Most subspecies of Salmonella produce hydrogen sulfide, which can readily be detected by growing them on media containing ferrous sulfate, such as is used in the triple sugar iron test (TSI). Most isolates exist in two phases: a motile phase I and a nonmotile phase II. Cultures that are nonmotile upon primary culture may be switched to the motile phase using a Cragie tube.
Salmonella is found worldwide in both cold-blooded and warm-blooded animals, and in the environment. They cause illnesses such as typhoid fever, paratyphoid fever, and food poisoning.
Salmonella infections are zoonotic and can be transferred between humans and nonhuman animals. Many infections are due to ingestion of contaminated food. For example, recent FDA studies link Guatemalan cantaloupes with Salmonella panama. In speaking of other salmonella serotypes, enteritis Salmonella and Salmonella typhoid/paratyphoid Salmonella, the latter—because of a special virulence factor and a capsule protein (virulence antigen)—can cause serious illness, such as Salmonella enterica subsp. enterica serovar Typhi. Salmonella typhi is adapted to humans and does not occur in other animals.
Salmonella species are facultative intracellular pathogens that enter cells via macropinosomes.
History
The genus Salmonella was named after Daniel Elmer Salmon, an American veterinary pathologist. While Theobald Smith was the actual discoverer of the type bacterium (Salmonella enterica var. Choleraesuis) in 1885, Dr. Salmon was the administrator of the USDA research program, and thus the organism was named after him by Smith. Smith and Salmon had been searching for the cause of common hog cholera and proposed this organism as the causal agent. Later research, however, would show this organism (now known as Salmonella enterica) rarely causes enteric symptoms in pigs, and was thus not the agent they were seeking (which was eventually shown to be a virus). However, related bacteria in the genus Salmonella were eventually shown to cause other important infectious diseases. The genus Salmonella was finally formally adopted in 1900 by J. Lignières for the many species of Salmonella, after Smith's first type-strain Salmonella cholera.
Source: wikipedia.org
Salmonella is found worldwide in both cold-blooded and warm-blooded animals, and in the environment. They cause illnesses such as typhoid fever, paratyphoid fever, and food poisoning.
Salmonella infections are zoonotic and can be transferred between humans and nonhuman animals. Many infections are due to ingestion of contaminated food. For example, recent FDA studies link Guatemalan cantaloupes with Salmonella panama. In speaking of other salmonella serotypes, enteritis Salmonella and Salmonella typhoid/paratyphoid Salmonella, the latter—because of a special virulence factor and a capsule protein (virulence antigen)—can cause serious illness, such as Salmonella enterica subsp. enterica serovar Typhi. Salmonella typhi is adapted to humans and does not occur in other animals.
Salmonella species are facultative intracellular pathogens that enter cells via macropinosomes.
History
The genus Salmonella was named after Daniel Elmer Salmon, an American veterinary pathologist. While Theobald Smith was the actual discoverer of the type bacterium (Salmonella enterica var. Choleraesuis) in 1885, Dr. Salmon was the administrator of the USDA research program, and thus the organism was named after him by Smith. Smith and Salmon had been searching for the cause of common hog cholera and proposed this organism as the causal agent. Later research, however, would show this organism (now known as Salmonella enterica) rarely causes enteric symptoms in pigs, and was thus not the agent they were seeking (which was eventually shown to be a virus). However, related bacteria in the genus Salmonella were eventually shown to cause other important infectious diseases. The genus Salmonella was finally formally adopted in 1900 by J. Lignières for the many species of Salmonella, after Smith's first type-strain Salmonella cholera.
Source: wikipedia.org