Shigella Sonnei Characteristics

Shigella sonnei is a species of bacterium of the genus Shigella that can cause an illness called shigellosis in humans. The bacteria are transmitted between infected hosts via contaminated water or food. Symptoms of shigellosis include fever, abdominal pain, and severe, often bloody diarrhea. Shigellosis is a serious condition; if you suspect you have shigellosis you should seek medical attention.

Physiology

• S. sonnei belong to the gram-negative category of bacteria, meaning that they have an outer membrane, an inner membrane and a thin mesh-like layer in between. They lack flagella and are facultative anaerobes, meaning they can carry out cellular respiration with or without oxygen. Like E. coli, they are glucose fermenters, meaning that they use a biochemical process called fermentation to extract energy from glucose.

Serotype

• An antigen is a molecule the immune system can recognize. Scientists sometimes classify bacteria based on the antigens they display. Shigella bacteria are divided into four different species depending on their serotype or the type of antigens they have in their cell wall. S. sonnei are serotype D.

Other Characteristics

• Like other Shigella bacteria, S. sonnei secretes a toxin called Shiga toxin, which binds to molecules called receptors on cells of the small intestine and blocks nutrient uptake. Once inside the cell, Shiga toxin also alters the large subunit of ribosomes, the complex molecular machines your cells use to synthesize proteins, thereby halting protein synthesis and killing cells.