Shigella sonnei
Jacob Lister

Shigella sonnei is a bacterium that is gram negative and non-motile. The bacterium is rod shaped in structure and is non-spore forming. The bacterium is also considered lactose fermentative and is a facultative anaerobe. The genome of the bacterium is a circular DNA structure and is approximately 4Mb. This bacterium’s genius is responsible for several foodborne illnesses found in several locations throughout the world from highly developed countries to the impoverished. And there effects upon the body vary from a slight diarrhea to dysentery.

Like most of the genius Shigella Shigella sonnei is a pathogen that causes shigellosis which is a foodborne illness. This illness accounts for less than 10 percent of food illnesses in the United States but taken to a Global scale Shigellosis is responsible for approximately 1,100,000 deaths per year with the majority of the total belonging to children under the age of five. The main foods that this bacterium is found on are salads, raw vegetables, dairy products, and poultry. The bacterium is not only found on the uncooked foods but also in some contaminated drinking supplies. The bacterium’s main mode of spreading is the fecal-oral route therefore in areas of poor sanitation this bacterium is a real problem.

Once the bacterium has entered into a human body through the fecal-oral route it takes as few as 10 cells to infect a person with shigellosis. The time of onset can very though from 12 to 50 hours after ingestion of the bacteria. The illness is caused by the Shigella attaching and penetrating into the epithelial layer of cells in the intestinal tract and particularly the mucosa. After penetration into the cell the bacteria multiple and lyses the cell to spread to more epithelial cells causing tissue destruction.  This then causes the immune system to react to the bacterium and the following symptoms can result due to both the bacteria and the body’s reactions. The symptoms include Abdominal pain; cramps; diarrhea; fever; vomiting; blood, pus, or mucus in stools; tenesmus.

While this bacteria is very severe it can still be treated with certain drugs and antibiotics, although this is becoming a more difficult task. The Shigella sonnei are becoming drug resistant. There has been classified a Shigella sonnei biotype g having a class 2 integron. The integron is a genetic element that is used in the resistance to drug therapies. This showing that this strain is starting to develop resistance to the cure to the illness shigellosis. But ultimately showing the resistance of pathogen everywhere.


Cheng, Susan. "Shigella sonnei." MicrobeWiki - MicrobeWiki. 27 July 2007. 23 Feb. 2009 <>.

Ranjbar, Reza, Aurora Aleo, Giovanni M. Giammanco, Anna M. Dionisi, Nourkhoda Sadeghifard, and Caterina Mammina. "Genetic relatedness among isolates of Shigella sonnei carrying class 2 integrons in Tehran, Iran, 2002–2003." 22 June 2007. BioMed. 23 Feb. 2009 <>.

"Shigella." Mayo Clinic medical information and tools for healthy living - 12 Apr. 2008. 23 Feb. 2009 <>.

Walderhaug, M. "US FDA/CFSAN - Bad Bug Book - Shigella spp." U.S. FDA / Center for Food Safety and Applied Nutrition. Jan. 1992. 23 Feb. 2009 <>.
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.


Return to Missouri S&T Microbiology HomePage Go to DJW's HomePage