Shigella dysenteriae: Difference between revisions
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{{Shigellosis}} | |||
{{About0|Shigellosis}} | |||
{{Seealso|Shigella}} | |||
{{CMG}} | |||
==Overview== | |||
'''''Shigella dysenteriae''''' is a species of the rod-shaped [[bacteria]]l [[genus]] ''[[Shigella]]''.<ref>{{cite book|title=Sherris medical microbiology: an introduction to infectious diseases|year=2004|publisher=McGraw-Hill Professional Med/Tech|isbn=978-0-8385-8529-0|edition=4th |editor=Ryan, Kenneth James; Ray, C. George}}</ref>{{page needed|date=February 2012}} ''Shigella'' species can cause [[shigellosis]] (bacillary [[dysentery]]). Shigellae are [[Gram-negative]], [[Endospore|nonspore-forming]], [[Facultative anaerobic organism|facultatively anaerobic]], [[Motility|nonmotile]] bacteria.<ref name=Baron>{{cite book|last=Hale|first=Thomas L.|last2=Keusch|first2=Gerald T.|title=Medical microbiology|year=1996|publisher=University of Texas Medical Branch|location=Galveston, Texas|isbn=978-0-9631172-1-2|url=http://www.ncbi.nlm.nih.gov/books/NBK8038/#A1269|edition=4|editor=Baron, Samuel|accessdate=February 11, 2012|chapter=Shigella: Structure, Classification, and Antigenic Types}}</ref> | |||
''S. dysenteriae'', spread by contaminated water and food, causes the most severe dysentery because of its potent and deadly [[Shiga toxin]], but other species may also be dysentery agents.<ref>{{cite journal |author=Herold S, Karch H, Schmidt H |title=Shiga toxin-encoding bacteriophages—genomes in motion |journal=[[International Journal of Medical Microbiology|Int J Med Microbiolo]] |volume=294 |issue=2–3 |pages=115–121 |year=2004 |pmid=15493821 |doi=10.1016/j.ijmm.2004.06.023 |url=http://linkinghub.elsevier.com/retrieve/pii/S1438-4221(04)00054-2}}</ref> Contamination is often caused by bacteria on unwashed hands during food preparation, or soiled hands reaching the mouth.{{Citation needed|date=February 2010}} | |||
==Diagnosis== | |||
Since the typical fecal specimen is not sterile, the use of selective plates is mandatory. [[XLD agar]], [[DCA agar]], or [[Hektoen enteric agar]] are inoculated; all give colorless colonies as the organism is not a [[lactose]] fermenter. Inoculation of a [[TSI slant]] shows an alkaline slant and acidic, but with no gas, or {{chem|link=hydrogen sulfide|H|2|S}} production. Following incubation on SIM, the culture appears nonmotile with no {{chem|H|2|S}} production. Addition of [[Indole test|Kovac's reagent]] to the SIM tube following growth typically indicates no [[indole]] formation ([[serotype]]s 2, 7, and 8 produce indole<ref>{{cite book |last1=Germani |first1=Y. |last2=Sansonetti |first2=P.J. |editor1-first=M. (editor-in-chief) |editor1-last=Dworkin |title= The Prokaryotes: Proteobacteria: gamma subclass |edition=3rd |volume=6 |year=2006 |publisher=Springer |isbn=0-387-25496-X |doi=10.1007/0-387-30746-x_6 |pages=99–122 |chapter=Chapter 3.3.6: The Genus ''Shigella''}}</ref>). | |||
''[[Shigella flexneri]]'' will produce acid and gas from glucose, and ''[[Shigella sonnei]]'' is [[mannitol]] and [[ornithine]] positive, and is also a late lactose fermenter (ONPG positive). Some ''Shigella'' species can produce indole. | |||
==References== | |||
{{reflist|colwidth=30em}} | |||
==External Links== | |||
*{{cite web |title=''Shigella dysenteriae'' |work=NCBI Taxonomy Browser |url=http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=622 |id=622}} | |||
{{Gram-negative bacterial diseases}} | |||
[[Category:Enterobacteria]] |
Latest revision as of 15:47, 8 December 2015
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Template:Seealso Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Shigella dysenteriae is a species of the rod-shaped bacterial genus Shigella.[1][page needed] Shigella species can cause shigellosis (bacillary dysentery). Shigellae are Gram-negative, nonspore-forming, facultatively anaerobic, nonmotile bacteria.[2]
S. dysenteriae, spread by contaminated water and food, causes the most severe dysentery because of its potent and deadly Shiga toxin, but other species may also be dysentery agents.[3] Contamination is often caused by bacteria on unwashed hands during food preparation, or soiled hands reaching the mouth.[citation needed]
Diagnosis
Since the typical fecal specimen is not sterile, the use of selective plates is mandatory. XLD agar, DCA agar, or Hektoen enteric agar are inoculated; all give colorless colonies as the organism is not a lactose fermenter. Inoculation of a TSI slant shows an alkaline slant and acidic, but with no gas, or H
2S production. Following incubation on SIM, the culture appears nonmotile with no H
2S production. Addition of Kovac's reagent to the SIM tube following growth typically indicates no indole formation (serotypes 2, 7, and 8 produce indole[4]).
Shigella flexneri will produce acid and gas from glucose, and Shigella sonnei is mannitol and ornithine positive, and is also a late lactose fermenter (ONPG positive). Some Shigella species can produce indole.
References
- ↑ Ryan, Kenneth James; Ray, C. George, ed. (2004). Sherris medical microbiology: an introduction to infectious diseases (4th ed.). McGraw-Hill Professional Med/Tech. ISBN 978-0-8385-8529-0.
- ↑ Hale, Thomas L.; Keusch, Gerald T. (1996). "Shigella: Structure, Classification, and Antigenic Types". In Baron, Samuel. Medical microbiology (4 ed.). Galveston, Texas: University of Texas Medical Branch. ISBN 978-0-9631172-1-2. Retrieved February 11, 2012.
- ↑ Herold S, Karch H, Schmidt H (2004). "Shiga toxin-encoding bacteriophages—genomes in motion". Int J Med Microbiolo. 294 (2–3): 115–121. doi:10.1016/j.ijmm.2004.06.023. PMID 15493821.
- ↑ Germani, Y.; Sansonetti, P.J. (2006). "Chapter 3.3.6: The Genus Shigella". In Dworkin, M. (editor-in-chief). The Prokaryotes: Proteobacteria: gamma subclass. 6 (3rd ed.). Springer. pp. 99–122. doi:10.1007/0-387-30746-x_6. ISBN 0-387-25496-X.
External Links
- "Shigella dysenteriae". NCBI Taxonomy Browser. 622.