Shigella dysenteriae
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| Shigella dysenteriae |
Description and significance
Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.
Shigella was discovered over 100 hundred years ago by the Japanese biologist Shiga, which the genus was named after. (reference) Shigella dysenteriae is gram-negative, meaning it contains a thinner peptidoglycan layer and an outer membrane. Shigella dysenteriae are rod (bacillus) shaped, non-motile bacteria. Their natural habitat is within the human gastro-intestinal tract, but it found within other primates as well. They are able to survive the harsh environment of the acids inside the intestinal tract. The accumulation of bacterial shigella dysenteriae is known to cause a condition known as shigellosis.
Genome structure
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Does it have any plasmids? Are they important to the organism's lifestyle?
Shigella dysenteriae has the smallest genome out of the genus Shigella, which contains three other species. It's genome consists of a single circular chromosome and 4,369,232 base pairs. It contains one plasmid.
Cell structure and metabolism
Describe any interesting features and/or cell structures; how it gains energy; what important molecules it produces
Shigella dysenteriae produces produce a toxin active on Vero cells (refernce 3).
Ecology
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.
Shigella dysenteriae can survive in faecally contaminated materials which can include water, foods, and other materials (reference 3). It can be transmitted by person to person contact. It is generally transmitted with the ingestion of water and food contaminated with the bacteria. It can cause deadly epidemics in the poorer countries which do not contain adequate sanitation and water treatment systems.
Pathology
How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
Shigella dysenteriae causes shigellosis (bacillary dysentery) in humans. It's also known to cause dysentery in other primates, but not in other animals. Shigella dysenteriae Common symptoms include acute bloody diarrhea, abdominal pains and cramps, fever, vomiting, dehydration, and tenesmus (reference 4). Shigella dysenteriae infection can also cause Hemolytic Uremic Syndrome (HUS), which is associatied with the fever and the production of Shiga toxin (reference 1).
Shigellosis usually resolves on its own in several days, but in smaller children the infection can be more severe, resulting in hospitalization or death. Once a person has become infected, they are not likely to get infected with the particular strain again, due to the bodies ability to produce antibodies. However, they can be reinfected by other types of Shigella (reference 1). Treatment, used generally in more severe cases, includes the application of antibiotics. The antibiotics will kill the bacteria inside the gastrointerstinal tract, shortening its lifespan and therefore shortening the course of the infection (reference 1).
Application to Biotechnology
Does this organism produce any useful compounds or enzymes? What are they and how are they used?
Current Research
Enter summaries of the most recent research here--at least three required
1. High Prevalence of Antimicrobial Resistance among Shigella Isolates in the United States Tested by the National Antimicrobial Resistance Monitoring System from 1999 to 2002 http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1346809&rendertype=abstract
2. RyhB, an iron-responsive small RNA molecule, regulates Shigella dysenteriae virulence http://www.ncbi.nlm.nih.gov/pubmed/17438026?dopt=Abstract
References
1. http://www.textbookofbacteriology.net/Shigella.html
2. http://www.genome.jp/kegg-bin/show_organism?org=sdy
3. http://www.microbionet.com.au/shigella.htm
4. http://www.emedicine.com/med/TOPIC2112.HTM
5. http://pathport.vbi.vt.edu/pathinfo/pathogens/Shigella.html