Salmonella enteriditis*

Synonyms

Salmonella enterica, serovar enteriditis

Classification

facultative anaerobic, gram- bacteria, rods

Diseases

Sites and Sources

Diagnostic Factors

Virulence Factors

Treatment and Prevention

Commentary

The nomenclature of Salmonella is in a continual state of flux, and the old three-species scheme has been officially superceded by a one species, multiple serovar system. We will refer to them here, by the old three species (enteriditis, cholerasuis, typhi) designation as it makes some sense in terms of disease. The new names are given as synonyms. S. typhimurium has been added also although it is almost identical in the range of disease it causes to S. enteriditis. In addition, there are many other serovars that cause a pattern of disease identical to that of enteriditis, and these are sometimes used as species names. The primary reservoir of S. enteriditis and S. cholerasuis is the intestinal tracts of animals, including livestock, poultry, and reptiles. Humans become infected by ingestion of contaminated food or water. Undercooked poultry and eggs are, perhaps, the most common sources. Children can become infected via their hands after handling pet dogs, cats, or turtles. Salmonellosis is an occupational hazard for workers in abbatoirs. Enterocolitis or food poisoning accompanied by nausea, vomiting, and watery or bloody diarrhea is the most common type of Salmonella infection. There are, literally, hundreds of strains of salmonella and the disease produced depends to some extent on which strain is causing the infection. Almost all strains of S. enteriditis, as opposed to S. cholerasuis and S. typhi, remain in the intestine. The diseases they cause are usually self limiting and no antibiotics are recommended. Antibiotics are used for septicemia or in the immunocompromised, in whom Salmonella infections can be severe and mimic typhoid fever. Salmonellae are members of the family Enterobacteriaceae. The identification of the Enterobacteriaceae is complicated and involves a large number of tests. Of primary importance is the fermentation of lactose, which Escherichia and Klebsiellae can accomplish, but which Shigella, Salmonella, and Proteus cannot. Other characteristics which can distinguish between the members of the family Enterobacteriaceae include indole, urease, hydrogen sulfide, and gas production. A variety of commercial products to test for these attributes quickly and simultaneously are available. One of these uses a plastic strip with 20 or so wells containing different kinds of dehydrated media. A single colony to be identified is suspended in 5 ml of saline, and this is used to both rehydrate and innoculate the media. Speciation is done on the basis of O (LPS) and H (flagellar) antigens.