Results for Shigella flexneri: Test | Results | Interpretation | Gram stain| Red; small bacilli with no arrangement| Gram-negative bacillus| 3% KOH| Positive for stringing| Verifies Gram-negative| Vancomycin | No zone of inhibition| Gram-negative (vancomycin resistant)| Motility | Only the length of stub is red | Negative for motility | Indole| Yellow layer after kovac’s reagent added| Negative for tryptophanase; Indole negative | Methyl Red | Turns red| Positive for acid at pH 4. or less ;MR positive| Voges-Proskauer| Stays yellow| Negative for acetoin; VP negative| Citrate Utilization| No growth, Stays green| Negative for citrate permease| Ornithine Decarboxylase | Yellow, negative | Decarboxylase enzyme absent, Only glucose fermented to acid| Lysine Decarboxylase| Yellow ,negative | Only glucose fermented to aid | Triple Sugar Iron(TSI)| Pink slant /yellow but | Glucose fermented to acid and protein in media was broken down to alkaline end product| Shigella is a genus of gamma proteobacteria in the family Enterobacteriaceae.
Shigellae are Gram-negative, nonmotile, non-spore forming, rod-shaped bacteria, very closely related to Escherichia Shigella were discovered over 100 years ago by the Japanese microbiologist, Shiga, for whom the genus is named.
There are four species of Shigella: S. boydii, S. dysenteriae, S. flexneri, and S. sonnei. Shigella sonnei, also known as Group D Shigella, accounts for over two-thirds of the shigellosis in the United States. Shigella flexneri, or Group B Shigella, accounts for almost all of the rest. Other types of Shigella are rare in this country, although they are important causes of disease in the developing world.
One type, Shigella dysenteriae type 1, causes deadly epidemics in many developing regions and nations. coli. Shigella flexneri is aleading cause of infant mortality in developing countries Shigella are Gram-negative, nonmotile, nonsporeforming rod-shaped bacteria that are highly infectious agents that are transmitted by the fecal-oral route. Shigella flexneri is a human intestinal pathogen, causing dysentery by invading the epithelium of the colon and is responsible, worldwide, for an estimated 165 million episodes of shigellosis and 1. million deaths per year. The bacterium is commonly found in water polluted with human faeces. It is transmitted in contaminated food or water and through contact between people. Upon infection, humans develop severe abdominal cramps, fever, and frequent passage of bloody stools. Shigellosis is not only a significant cause of infant mortality in developing nations but maintains endemic levels of infection worldwide. New treatments are needed for this highly infectious microbe because antibiotics are often inadequate and drug-resistant strains are on the rise.
Currently, no vaccines exist and the World Health Organisation considers the development of a vaccine a priority. The publication of the genome sequence is an important step in achieving this goal. The sequenced S. flexneri strain was isolated from a patient with severe acute shigellosis in Beijing in 1984, the bacterium has about 4,700 genes. The S. flexneri genome consists of a chromosome and a smaller DNA structure called a virulence plasmid, which contains genes important in causing disease.
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Shigella Flexneri. (2016, Sep 13). Retrieved from https://graduateway.com/shigella-flexneri/