Shigella
Shigella | |
---|---|
Photomicrograph of Shigella sp. in a stool specimen | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Pseudomonadota |
Class: | Gammaproteobacteria |
Order: | Enterobacterales |
Family: | Enterobacteriaceae |
Genus: | Shigella Castellani & Chalmers 1919 |
Species | |
Shigella is a
Shigella causes disease in primates, but not in other mammals; it is the causative agent of human shigellosis.[2] It is only naturally found in humans and gorillas.[3][4] During infection, it typically causes dysentery.[5]
Shigella is a leading cause of bacterial diarrhea worldwide, with 80–165 million annual cases (estimated)[6] and 74,000 to 600,000 deaths.[6][7] It is one of the top four pathogens that cause moderate-to-severe diarrhea in African and South Asian children.[8]
Classification
Shigella species are classified by three serogroups and one serotype:
- Serogroup A: S. dysenteriae (15 serotypes)[9]
- Serogroup B: S. flexneri (9 serotypes)[10]
- Serogroup C: S. boydii (19 serotypes)[11]
- Serogroup D: S. sonnei (one serotype)[citation needed]
Groups A–C are physiologically similar; S. sonnei (group D) can be differentiated on the basis of biochemical metabolism assays.[12] Three Shigella groups are the major disease-causing species: S. flexneri is the most frequently isolated species worldwide, and accounts for 60% of cases in the developing world; S. sonnei causes 77% of cases in the developed world, compared to only 15% of cases in the developing world; and S. dysenteriae is usually the cause of epidemics of dysentery, particularly in confined populations such as refugee camps.[13]
Each of the Shigella genomes includes a virulence plasmid that encodes conserved primary virulence determinants. The Shigella chromosomes share most of their genes with those of E. coli K12 strain MG1655.[14]
Phylogenetic studies indicate Shigella is more appropriately treated as a subgroup of Escherichia[15] (see Escherichia coli#Diversity for details).
Pathogenesis
Shigella infection is typically by
Because they do not interact with the apical surface of epithelial cells — preferring the basolateral side — Shigella species invade the host through the
After infection, Shigella cells multiply
Discovery
The Shigella genus is named after Japanese physician Kiyoshi Shiga, who researched the cause of dysentery. Shiga entered the Tokyo Imperial University School of Medicine in 1892, during which he attended a lecture by Shibasaburo Kitasato. Shiga was impressed by Kitasato's intellect and confidence, so after graduating, he went to work for him as a research assistant at the Institute for Infectious Diseases. In 1897, Shiga focused his efforts on what the Japanese referred to as a sekiri (dysentery) outbreak. Such epidemics were detrimental to the Japanese people and occurred often in the late 19th century. The 1897 sekiri epidemic affected >91,000, with a mortality rate of >20%.[22] Shiga studied 32 dysentery patients and used Koch's postulates to successfully isolate and identify the bacterium causing the disease. He continued to study and characterize the bacterium, identified its methods of (Shiga-) toxin production, and worked to create a vaccine for the disease.[citation needed]
See also
References
- PMID 12054222.
- ISBN 978-0-8385-8529-0.[page needed]
- ISBN 978-92-4-156305-5. Archived from the originalon June 30, 2013.
- ^ "Shigellosis" (PDF). European Association of Zoo and Wildlife Veterinarians. Archived from the original (PDF) on 2015-09-27.
- ISBN 978-0-7234-3259-3.
- ^ ISBN 978-0-19-937915-6. Retrieved 22 June 2016.
- PMID 26979135.
- S2CID 205969172.
- PMID 7615772.
- S2CID 7360433.
- PMID 2251827.
- ^ PMID 21413292.
- ^ "Shigellosis" (PDF). State of the art of new vaccine research and development. Immunization, Vaccines and Biologicals. World Health Organization. 2006. pp. 10–2. Archived (PDF) from the original on 2015-09-27.
- PMID 16275786.
- PMID 22266241.
- ISBN 978-0-07-146031-6.
- PMID 1729185.
- S2CID 23962367.
- ^ Todar, Kenneth. "Shigella and Shigellosis". Todar's Online Textbook of Bacteriology.[self-published source]
- PMID 11553531.
- PMID 12787523.
- PMID 10524979.
External links
- Shigella genomes and related information at PATRIC, a Bioinformatics Resource Center funded by NIAID
- Vaccine Resource Library: Shigellosis and enterotoxigenic Escherichia coli (ETEC)
- US Centers for Disease Control and Prevention. Shigella - Shigellosis