Salmonella

Discovered by : Theobald Smith-D. Salmon

Discovered in year : 1885

Salmonella is a bacterium that causes one of the most common enteric (intestinal) infections amongst humans. It is a rod-shaped, gram-negative, facultative anaerobe in the family Enterobacteriaceae.  Salmonella is mostly prevalent in certain animals, such as cattle and pigs. The genus Salmonella is divided into two species, S. enterica and S. bongori (CDC). Salmonella typhi is adapted to humans an cause serious illness like typhoid but it does not occur in animals. Enteritis Salmonella (e.g., Salmonella enterica subsp. enterica serovar Enteritidis) can cause diarrhoea, which usually does not require antibiotic treatment. Salmonella infections are zoonotic; they can be transmitted by humans to animals and vice versa. Infection via food is also possible. 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.

History - Salmonella is named after Daniel Elmer Salmon (July 23, 1850 – August 30, 1914) who was a U.S. veterinary surgeon. During 1884 he was head of the bureau of animal industry, a division of U.S. department of agriculture. Along with his assistant, noted pathologist, Theobald Smith, they eventually controlled the two major threats to health and industry, contagious pleuro-pneumonia and Texas fever in cattle. The hog cholera bacillus - Salmonella cholerae-suis, was first isolated by Theobald Smith in 1885 but Salmon insisted on standing as the sole senior author of this research and other research as well. And since Salmon was the administrator of the USDA research program, the bacteria was named after him and not Smith. However the discovery benefited mankind more than it did to them as during the study of hog cholera they demonstrated that dead (heat killed) organisms could immunize animals against living organisms.

Development in the discovery of Salmonella

In 1896, the first preventive measure against Salmonella was discovered as an antityphoid vaccine which was developed by the British surgeon Almroth Wright. The Vaccine was successfully used during World War I to reduce the number of soldiers who died of enteric fever (S. typhi).

By 1909, the first typhoid inoculation was conducted by the united states army medical school and in 1944, bottling of typhoid vaccine was conducted by division of biologic products, U.S. army of medical department professional service schools.

Role of the discovery of Salmonella in the improvement of human life

• Since it's discovery, more than 2,000 subtypes have been identified which has led to it's prevention and control.

• It led to effective food safety education and control.

• It also led to the awareness of changes in micro-organisms, evolution of new pathogens, development of antibiotic resistance, changes in the ability to survive in adverse environmental conditions.

• It also led to awareness about the importance of intensive animal maintenance.