Salmonella: Difference between revisions

Jump to navigation Jump to search
VisualWikitext
No edit summary
Line 3: Line 3:
{{CMG}}; {{AE}} {{JS}} {{JM}}
{{CMG}}; {{AE}} {{JS}} {{JM}}


<!--
==Overview==
Enterobacteriaceae of the genus Salmonella, a gram-negative rod-shaped bacilli. Approximately 2000 serotypes cause human disease.
==Causes==
Enterobacteriaceae of the genus [[Salmonella]], a [[gram-negative]] rod-shaped bacilli. Approximately 2000 serotypes cause human disease.
Salmonellosis is an infection with a bacteria called Salmonella. The Salmonella germ is actually a group of bacteria that can cause [[diarrheal]] illness in humans. They are microscopic living creatures that pass from the feces of people or animals, to other people or other animals. There are many different kinds of Salmonella bacteria.<ref>http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salmonellosis_g.htm </ref>
-->
==Overview==
==Overview==
'''''Salmonella''''' is a [[genus]] of rod-shaped [[Gram-negative]] [[enterobacteriaceae|enterobacteria]].<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | id = ISBN 0-8385-8529-9 }}</ref> ''Salmonella'' species are [[Motility|motile]] and produce [[hydrogen sulfide]].<ref name=Baron>{{cite book | author = Giannella RA | editor = Baron S ''et al'' (eds.) | chapter = Salmonella | title = Baron's Medical Microbiology | edition = 4th ed. | publisher = Univ of Texas Medical Branch | year = 1996 | chapterurl = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.1929| isbn = 0-9631172-1-1 }}</ref>
'''''Salmonella''''' is a [[genus]] of rod-shaped [[Gram-negative]] [[enterobacteriaceae|enterobacteria]].<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | id = ISBN 0-8385-8529-9 }}</ref> ''Salmonella'' species are [[Motility|motile]] and produce [[hydrogen sulfide]].<ref name=Baron>{{cite book | author = Giannella RA | editor = Baron S ''et al'' (eds.) | chapter = Salmonella | title = Baron's Medical Microbiology | edition = 4th ed. | publisher = Univ of Texas Medical Branch | year = 1996 | chapterurl = http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mmed.section.1929| isbn = 0-9631172-1-1 }}</ref>
Line 32: Line 22:


When the sample has a low number of [[bacteria]], special enrichment broths, such as the selenite-based enrichment broth, may be used to increase the number of [[bacteria]].<ref name="PerezCavalli2003">{{cite journal|last1=Perez|first1=J. M.|last2=Cavalli|first2=P.|last3=Roure|first3=C.|last4=Renac|first4=R.|last5=Gille|first5=Y.|last6=Freydiere|first6=A. M.|title=Comparison of Four Chromogenic Media and Hektoen Agar for Detection and Presumptive Identification of Salmonella Strains in Human Stools|journal=Journal of Clinical Microbiology|volume=41|issue=3|year=2003|pages=1130–1134|issn=0095-1137|doi=10.1128/JCM.41.3.1130-1134.2003}}</ref>
When the sample has a low number of [[bacteria]], special enrichment broths, such as the selenite-based enrichment broth, may be used to increase the number of [[bacteria]].<ref name="PerezCavalli2003">{{cite journal|last1=Perez|first1=J. M.|last2=Cavalli|first2=P.|last3=Roure|first3=C.|last4=Renac|first4=R.|last5=Gille|first5=Y.|last6=Freydiere|first6=A. M.|title=Comparison of Four Chromogenic Media and Hektoen Agar for Detection and Presumptive Identification of Salmonella Strains in Human Stools|journal=Journal of Clinical Microbiology|volume=41|issue=3|year=2003|pages=1130–1134|issn=0095-1137|doi=10.1128/JCM.41.3.1130-1134.2003}}</ref>
[[Salmonella]] isolates should be serogrouped with polyvalent antisera or in public health centers. [[Salmonella]] are serogrouped according to:<ref>{{cite book | last = Murray | first = Patrick | title = Medical microbiology | publisher = Elsevier/Saunders | location = Philadelphia | year = 2013 | isbn = 0323086926 }}</ref>
*Capsular [[antigen]]
*[[Polysaccharide]] O antigens
*Flagellar [[antigens]]
Different [[salmonella]] serotypes may be distinguished according to the different [[metabolism]] of sugars.<ref>{{cite book | last = Mandell | first = Gerald | title = Mandell, Douglas, and Bennett's principles and practice of infectious diseases | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | year = 2010 | isbn = 0443068399 }}</ref>


===Infectious Cycle===
===Infectious Cycle===
Line 66: Line 49:
*Formerly [[subspecies]] V<ref name="pmid15313257">{{cite journal| author=Popoff MY, Bockemühl J, Gheesling LL| title=Supplement 2002 (no. 46) to the Kauffmann-White scheme. | journal=Res Microbiol | year= 2004 | volume= 155 | issue= 7 | pages= 568-70 | pmid=15313257 | doi=10.1016/j.resmic.2004.04.005 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15313257  }} </ref>
*Formerly [[subspecies]] V<ref name="pmid15313257">{{cite journal| author=Popoff MY, Bockemühl J, Gheesling LL| title=Supplement 2002 (no. 46) to the Kauffmann-White scheme. | journal=Res Microbiol | year= 2004 | volume= 155 | issue= 7 | pages= 568-70 | pmid=15313257 | doi=10.1016/j.resmic.2004.04.005 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15313257  }} </ref>


<!--
===Serovars===
[[Salmonella]] subspecies may be serogrouped, into more than 2500 serovars with polyvalent antisera. For this division the following bacterial structures are considered:<ref>{{cite book | last = Murray | first = Patrick | title = Medical microbiology | publisher = Elsevier/Saunders | location = Philadelphia | year = 2013 | isbn = 0323086926 }}</ref>
*Capsular [[antigen]]
*[[Polysaccharide]] O antigens
*Flagellar [[antigens]]


Members of the seven Salmonella subspecies can be serotyped into one of more than 2500 serotypes (serovars) according to antigenically diverse surface structures: somatic O antigens, the carbohydrate component of lipopolysaccharide, and flagellar (H) antigens (Table 223- 1).13 The name usually refers to the location where the Salmonella serotype was first isolated. According to the current Salmonella nomenclature system in use at the U.S. Centers for Disease Control and Prevention (CDC) and World Health Organization laboratories, the full taxonomic designation Salmonella enterica subspecies enterica serotype Typhimurium can be shortened to Salmonella serotype Typhimurium or Salmonella Typhimurium.14 The authors have chosen to use the abbreviated form in this chapter and will omit the “sero- type,” for example, designating “Salmonella serotype Typhimurium” as “Salmonella Typhimurium.”
Different [[salmonella]] serotypes may be distinguished according to the different [[metabolism]] of sugars.<ref>{{cite book | last = Mandell | first = Gerald | title = Mandell, Douglas, and Bennett's principles and practice of infectious diseases | publisher = Churchill Livingstone/Elsevier | location = Philadelphia, PA | year = 2010 | isbn = 0443068399 }}</ref>
 
-->


==Tropism==
==Tropism==

Revision as of 15:44, 21 August 2014

Salmonellosis Microchapters

Home

Patient Information

Overview

Historical Perspective

Pathophysiology

Causes

Differentiating Salmonellosis from other Diseases

Epidemiology and Demographics

Risk Factors

Natural History, Complications and Prognosis

Diagnosis

History and Symptoms

Physical Examination

Laboratory Findings

Treatment

Medical Therapy

Primary Prevention

Cost-Effectiveness of Therapy

Future or Investigational Therapies

Case Studies

Case #1

Salmonella On the Web

Most recent articles

Most cited articles

Review articles

CME Programs

Powerpoint slides

Images

American Roentgen Ray Society Images of Salmonella

All Images
X-rays
Echo & Ultrasound
CT Images
MRI

Ongoing Trials at Clinical Trials.gov

US National Guidelines Clearinghouse

NICE Guidance

FDA on Salmonella

CDC on Salmonella

Salmonella in the news

Blogs on Salmonella

Directions to Hospitals Treating Salmonellosis

Risk calculators and risk factors for Salmonella

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: João André Alves Silva, M.D. [2] Jolanta Marszalek, M.D. [3]

Overview

Salmonella is a genus of rod-shaped Gram-negative enterobacteria.[1] Salmonella species are motile and produce hydrogen sulfide.[2]

Taxonomy

Cellular organism; Bacteria; Proteobacteria; Gammaproteobacteria; Enterobacteriales; Enterobacteriaceae[3]

Biology

Computer-generated image of three drug-resistant non-typhoidal Salmonella bacteria. Adapted from Public Health Image Library (PHIL), Centers for Disease Control and Prevention.[4]
Colonial growth pattern displayed by Salmonella enterica subsp. arizonae, formerly Salmonella choleraesuis and Arizona hinshawii bacteria grown on a blood agar culture plate Adapted from Public Health Image Library (PHIL), Centers for Disease Control and Prevention.[4]

Salmonella is a Gram-negative bacterium, facultatively intracellular anaerobic, non-spore-forming bacilli. It measures 2 to 3 by 0.4 to 0.6 μm. Salmonellae do not ferment lactose, reduce nitrates, produce acid on glucose fermentation and are non producers of cytochrome oxidase.[5] Due to the presence of flagella, almost all salmonella are motile. 1% of the bacteria are able to ferment lactose, which may be responsible for its non-detection in media other than MacConkey agar.

For the isolation of salmonella in culture media, freshly passed stool are preferred. Common media for the growth of salmonella include: MacConkey agar, deoxycholate agar, and xylose-lysine-deoxycholate agar.[6]

When the sample has a low number of bacteria, special enrichment broths, such as the selenite-based enrichment broth, may be used to increase the number of bacteria.[6]

Infectious Cycle

Salmonella enterica enters the body through the mouth, by ingestion of contaminated food and water. For the bacteria to cause disease, an inoculum of about 50 000 bacteria is often required. Once in the intestine, the bacteria will first localize at the apical epithelium. Salmonella will then initiate bacterial mechanisms that allow host cell invasion, inducing inflammatory changes, such as:[7][8][9][10]

Different serovars will have different preferable intestinal locations. An example is the enterocolitis at the terminal ileum, cecum, and proximal colon caused by serovar Typhimurium. Intestinal disease is marked by neutrophil migration to the intestinal epithelium. This recruitment is done by the secretion of interleukin-8, induced by Salmonella.[11]

Classification

Before 1983 Salmonella were classified in different species. However, genome studies have shown high levels of DNA similarities among the different types of salmonella, which lead to the actual classification of salmonella in 2 different species:

Salmonella enterica

  • Contains six subspecies - I, II, IIIa, IIIb, IV, and VI:[12][13]
    • I - enterica
    • II - salamae
    • III - arizonae
    • IIIb - diarizonae
    • IV - houtenae
    • VI - indica
  • Subspecies I contains most pathogenic serotypes for humans (99.5%)
  • Subspecies IIIa and IIIb, formerly belonging to the genus Arizonae, are responsible for rare human infections

Salmonella bongori

Serovars

Salmonella subspecies may be serogrouped, into more than 2500 serovars with polyvalent antisera. For this division the following bacterial structures are considered:[15]

Different salmonella serotypes may be distinguished according to the different metabolism of sugars.[16]

Tropism

Natural Reservoir

Different salmonella serovars may have different natural reservoirs. Common types of serovars of salmonella enterica that infect the human gastrointestinal tract include the serovars Sendai, Typhi, and Paratyphi. These have humans as their only natural host.

Related Chapters

References

  1. ↑ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
  2. ↑ Giannella RA (1996). "Salmonella". In Baron S et al (eds.). Baron's Medical Microbiology (4th ed. ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1.
  3. ↑ "Salmonella (Taxonomy)".
  4. ↑ 4.0 4.1 "Public Health Image Library (PHIL), Centers for Disease Control and Prevention".
  5. ↑ Mandell, Gerald (2010). Mandell, Douglas, and Bennett's principles and practice of infectious diseases. Philadelphia, PA: Churchill Livingstone/Elsevier. ISBN 0443068399.
  6. ↑ 6.0 6.1 Perez, J. M.; Cavalli, P.; Roure, C.; Renac, R.; Gille, Y.; Freydiere, A. M. (2003). "Comparison of Four Chromogenic Media and Hektoen Agar for Detection and Presumptive Identification of Salmonella Strains in Human Stools". Journal of Clinical Microbiology. 41 (3): 1130–1134. doi:10.1128/JCM.41.3.1130-1134.2003. ISSN 0095-1137.
  7. ↑ McGovern VJ, Slavutin LJ (1979). "Pathology of salmonella colitis". Am J Surg Pathol. 3 (6): 483–90. PMID 534385.
  8. ↑ Giannella RA, Formal SB, Dammin GJ, Collins H (1973). "Pathogenesis of salmonellosis. Studies of fluid secretion, mucosal invasion, and morphologic reaction in the rabbit ileum". J Clin Invest. 52 (2): 441–53. doi:10.1172/JCI107201. PMC 302274. PMID 4630603.
  9. ↑ Clarke RC, Gyles CL (1987). "Virulence of wild and mutant strains of Salmonella typhimurium in ligated intestinal segments of calves, pigs, and rabbits". Am J Vet Res. 48 (3): 504–10. PMID 3551701.
  10. ↑ Finlay BB, Heffron F, Falkow S (1989). "Epithelial cell surfaces induce Salmonella proteins required for bacterial adherence and invasion". Science. 243 (4893): 940–3. PMID 2919285.
  11. ↑ McCormick BA, Colgan SP, Delp-Archer C, Miller SI, Madara JL (1993). "Salmonella typhimurium attachment to human intestinal epithelial monolayers: transcellular signalling to subepithelial neutrophils". J Cell Biol. 123 (4): 895–907. PMC 2200157. PMID 8227148.
  12. ↑ "The type species of the genus Salmonella Lignieres 1900 is Salmonella enterica (ex Kauffmann and Edwards 1952) Le Minor and Popoff 1987, with the type strain LT2T, and conservation of the epithet enterica in Salmonella enterica over all earlier epithets that may be applied to this species. Opinion 80". Int J Syst Evol Microbiol. 55 (Pt 1): 519–20. 2005. PMID 15653929.
  13. ↑ Tindall BJ; Grimont PAD, Garrity GM; Euzéby JP (2005). "Nomenclature and taxonomy of the genus Salmonella". Int J Syst Evol Microbiol. 55: 521&ndash, 524. PMID 15653930.
  14. ↑ Popoff MY, Bockemühl J, Gheesling LL (2004). "Supplement 2002 (no. 46) to the Kauffmann-White scheme". Res Microbiol. 155 (7): 568–70. doi:10.1016/j.resmic.2004.04.005. PMID 15313257.
  15. ↑ Murray, Patrick (2013). Medical microbiology. Philadelphia: Elsevier/Saunders. ISBN 0323086926.
  16. ↑ Mandell, Gerald (2010). Mandell, Douglas, and Bennett's principles and practice of infectious diseases. Philadelphia, PA: Churchill Livingstone/Elsevier. ISBN 0443068399.


Template:WikiDoc Sources

Template:WikiDoc Sources

Retrieved from "https://www.wikidoc.org/index.php?title=Salmonella&oldid=1011212"