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Veterinary bacteriology: information about important bacteria
Veterinary bacteriology

Species/Subspecies: Shigella dysenteriae
Etymology: Genus name: named after the Japanese bacteriologist K. Shiga, who first (1896) discovered the bacterium, which causes dysentery
Species name: of dysentery
Significance:Outbreaks of human dysentery are not common in Sweden (about 5 cases per year) and the disease occurs primarely in developing countries. However, a comparatively big outbreak (45 persons) has recently (May-June, 2009) occured in Sweden. The suspected infection source was contaminated imported vegetables.
Type Strain: ATCC 13313 = NCTC 4837.
Macromorphology (smell):
Micromorphology: Small (0.4-0.6 x 1-3 µm), non-motile rods.
Gram +/Gram -:G-
Metabolism: Facultatively anaerobic.
Other Enzymes: Esculinase -, tryptophanase V (serotype 1: -, serotype 2: +), urease -.
Biochemical Tests: Citrate -, methyl red +, Voges-Proskauer -.
Fermentation of carbohydrates:
Glucose (gas) -, melibios -, xylos -.
Spec. Char.:
Disease:Shigellosis or bacillary dysentery.
Hosts: Primates (including humans).
Clinical Picture: Fever, vomitting, abdominal pain and mucoid bloody diarrhea.
Virulence Factors: The shigatoxin (AB5), which is coded by the stx gene and which is composed of two different subunits (A and B). B is a pentamer, which makes it possible for the toxin to bind to a specific glycolipid on the cellsurface. Then the A subunit can enter the cell, where it will be cleaved to an active exonuclease (A1). A1 inhibits protein biosynthesis by removing an adenosine residue from the 28S rRNA. This will in turn result in damages on epithelial cells.
Genome Sequence:
Acc-noStrainSize (bp)Genome
CP000034 Sd197 4 369 232 1c + 2c 

16S rRNA Seq.:
Acc-noStrainNumber of NTOperon
X96966 ATCC 13313T 1487 

Four species have been described within the genus Shigella. These species and Escherichia coli are all very closely related and can phylogenetically be regarded as the same species. In spite of that fact, they have been taxonomically arranged into two different genera.
Legislation: Human dysentery is in Sweden classified as a notifiable disease and it is compulsary to report it to the Public Health Agency of Sweden. S. dysenteriae belongs to category B as a potential biological weapon according to NIAID.
Comment:Escherichia coli of type VTEC (verotoxin producing E. coli) has Shiga like toxins.


New names of taxa within the classification category phylum

During October 2021, an article was published by A. Oren och G.M. Garrity, in which new names are proposed for a number of taxa within the classification category phylum. This has resulted in many discussions in social media about whether it was really necessary to make these changes, which have created confusion among microbiologists and other professionals who come into contact with bacteriology.

Published 2022-09-28. Read more...

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