What Is a Shiga Toxin?
Shigella is the most common pathogen of bacterial dysentery in humans, commonly known as Shigella. According to biochemical reactions and serological tests, the bacteria in this genus are divided into four groups: dysentery, F. fowlii, B. bovis, and Shigella s. The culture characteristics are aerobic or facultative anaerobic, and it grows turbidly in the liquid medium, forming medium-sized, translucent smooth colonies of about 2mm in diameter on ordinary agar plates and SS medium. Shigella can be formed Flat, rough colonies.
- Shigella bacteria are the pathogens of human bacterial dysentery, commonly known as dysentery bacterium. Primates are also their natural hosts. Bacterial dysentery is mainly prevalent in developing countries and is a common disease. The annual number of cases in the world exceeds 200 million and the annual number of deaths reaches 650,000. Bacteria of this genus include Shigella dysenteriae, Shigella flexneri, Shigella bowelii and Shigella, 47 serotypes [1]
- The size is 0.5-0.7mx2-3m, no capsule, no flagella, no spore formation, and some strains have pili. Small, translucent, colorless colonies formed on the selection medium. This genus is weaker in biochemical response than other enterobacteria. Decomposing glucose generally does not produce gas. It does not decompose urea, does not form hydrogen sulfide, and cannot use citrate as a carbon source. Most Shigella do not break down lactose, but Shigella in Songi can slowly ferment lactose.
- This genus has O antigen and K antigen, but no H antigen. The O antigen is the basis for classification. The K antigen can prevent the O antigen from agglutinating with the corresponding O antibody, and this inhibition can be eliminated after heating. According to the structure of Shigella O antigen, it can be divided into four groups and 39 serotypes. F. dysenteriae is more common in China, followed by S. dysenteriae in Song [2]
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