Salmonella: A bacteria with incredible diversity and application

Salmonella is a bacteria that can cause typhoid fever and diarrhea in humans and animals. For each year, 16 million cases of typhoid fever are reported and cause 600,000 deaths.[1] It also caused more than 15% of infection cases in the U.S. each year.[2] People spent several billion dollars annually to try to prevent Salmonella infection and treat patients infected with Salmonella.[3]

Why Salmonella so difficult to prevent and treat? One of the reasons may be extremely high diversity. Using the number of types of antigen on the surface of bacteria, people can classify and then annotate their sub-type (serovar). Using this classify approach, Salmonella includes more than 2500 serovars. In addition, different serovars have different behavior during interaction with different species. For example, serovar Typhi infects only humans.[4] This make people more difficult to treat and prevent.

One of the other reasons may be the capability of survival in mammalian cells, including macrophages, which is a type of white blood cells.[4] Generally, bacteria and pathogens should be swallowed and digested by macrophages, but Salmonella has special capacity to resist the digestion. They can even replicate inside macrophages. People are trying to understand the mechanism of the digestion resistance.

However, the capability of survival in mammal cells provides several interesting medical applications. Since Salmonella can seize the resource of host cells and restrict the growth of the host cells, people are trying to let Salmonella infect tumor cells.[5]

It is interesting to study more about Salmonella so that people can prevent them and utilize them!



  1. Parry, C. M., Hien, T. T., Dougan, G., White, N. J., & Farrar, J. J. (2002). Typhoid Fever. New England Journal of Medicine, 347(22), 1770–1782.
  2. Brenner, F. W., Villar, R. G., Angulo, F. J., Tauxe, R., & Swaminathan, B. (2000). Salmonella nomenclature. Journal of clinical microbiology38(7), 2465-2467.
  3. Frenzen, P. D., & Riggs, T. L. (1999). Salmonella Cost Estimate Updated Using FoodNet Data. Food Review22(2), 10-15.
  4. Faucher, S. P., Porwollik, S., Dozois, C. M., McClelland, M., & Daigle, F. (2006). Transcriptome of Salmonella enterica serovar Typhi within macrophages revealed through the selective capture of transcribed sequences. Proceedings of the National Academy of Sciences103(6), 1906-1911.
  5. Arrach, N., Cheng, P., Zhao, M., Santiviago, C. A., Hoffman, R. M., & McClelland, M. (2010). High-throughput screening for Salmonella avirulent mutants that retain targeting of solid tumors. Cancer research70(6), 2165-2170.