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==Overview==
==Overview==
'''''Brucella''''' is a [[genus]] of [[Gram-negative]] [[bacterium|bacteria]].<ref name=Sherris>{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref> They are small (0.5 to 0.7 by 0.6 to 1.5 µm), non-[[motile]], encapsulated [[coccobacillus|coccobacilli]].
Human brucellosis is caused by four [[Brucella|Brucellae]] species: [[Brucella abortus|''B. abortus'']], [[Brucella canis|''B. canis'']], [[Brucella melitensis|''B. melitensis'']], and ''B. suis''.<ref>{{Cite web|url=http://www.who.int/csr/resources/publications/Brucellosis.pdf|title=WHO|last=|first=|date=|website=|publisher=|access-date=}}</ref>


''Brucella'' is the cause of [[brucellosis]], a true [[zoonosis|zoonotic]] disease (i.e. human-to-human transmission has not been identified).<ref name=Sherris /> It is transmitted by ingesting infected food, direct contact with an infected animal, or inhalation of aerosols. Minimum infectious exposure is between 10 - 100 organisms. [[Brucellosis]] primarily occurs through occupational exposure (e.g. exposure to cattle, sheep, pigs), but also by consumption of unpasteurised milk products.
==Causes==
*'''''[[Brucella]]''''' is a genus of [[gram-negative bacteria]].<ref name="Sherris">{{cite book | author = Ryan KJ, Ray CG (editors) | title = Sherris Medical Microbiology | edition = 4th ed. | publisher = McGraw Hill | year = 2004 | isbn = 0-8385-8529-9 }}</ref>They are small (0.5 to 0.7 by 0.6 to 1.5 µm), non-motile and encapsulated [[coccobacilli]].  


There are a few different species of ''Brucella'', each with a slightly different presentation, such as B. melitensis, B. abortus, B. suis and B. citicosis.
=== Brucella species ===
''[[Brucella]]'' species have been found primarily in mammals. <ref name="pmid15930423">{{cite journal| author=Pappas G, Akritidis N, Bosilkovski M, Tsianos E| title=Brucellosis. | journal=N Engl J Med | year= 2005 | volume= 352 | issue= 22 | pages= 2325-36 | pmid=15930423 | doi=10.1056/NEJMra050570 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15930423  }} </ref> Brucellla species, with their host and degree of virulence is described below:<ref>{{Cite web|url=http://www.who.int/csr/resources/publications/Brucellosis.pdf|title=WHO|last=|first=|date=|website=|publisher=|access-date=}}</ref>
{| style="border: 0px; font-size: 90%; margin: 3px;" align="center"
|+
! style="width: 180px;background: #4479BA" |{{fontcolor|#FFF| Species}}
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| Host}}
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| Human Virulence}}
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''B. melitensis''
| style="background: #F5F5F5; text-align:center" | Goats, sheep, cattle, buffaloes, dogs and camels
| style="background: #F5F5F5; text-align:center" | ++++
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''B. abortus''
| style="background: #F5F5F5; text-align:center" | Cattle, buffaloes, bison, dogs, elk, and horses
| style="background: #F5F5F5; text-align:center" | ++/+++
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''B. canis''
| style="background: #F5F5F5; bold; text-align:center" | Dogs
| style="background: #F5F5F5; text-align:center" | +
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''B. suis''
| style="background: #F5F5F5; text-align:center" | Pigs and sheep
| style="background: #F5F5F5; text-align:center" | +
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | ''B. ovis''
| style="background: #F5F5F5; text-align:center" | Sheep
| style="background: #F5F5F5; text-align:center" | -
|-
|}


==Laboratory isolation==
=== Tests to differentiate brucella species ===
''Brucella'' are slow-growing, but may be isolated from normal blood cultures using standard media.  In traditional blood culture media, prolonged incubation (up to 6 weeks) may be required, but on modern automated machines the cultures often come positive within seven days.  On [[Gram stain]] they appear as dense clumps of Gram-negative coccobacilli and are exceedingly difficult to see.
Following tests may be used to differentiate between the different species of brucella.<ref>{{Cite web|url=http://www.who.int/csr/resources/publications/Brucellosis.pdf|title=WHO|last=|first=|date=|website=|publisher=|access-date=}}</ref>
 
{| style="border: 0px; font-size: 90%; margin: 3px;" align="center"
Laboratory acquired brucellosis is common.<ref name=Robichaud_2004>{{cite journal |author=Robichaud S, Libman M, Behr M, Rubin E |title=Prevention of laboratory-acquired brucellosis |journal=Clin. Infect. Dis. |volume=38 |issue=12 |pages=e119-22 |year=2004 |pmid=15227634 |doi=10.1086/421024}}</ref>  This most often happens when the disease is not thought of until cultures become positive, by which time the specimens have already been handled by a number of laboratory staff. The idea of preventative treatment is to stop people who have been exposed to ''Brucella'' from becoming unwell with the disease.
|+
 
! style="width: 180px;background: #4479BA" |{{fontcolor|#FFF| Test}}
There are no clinical trials to be relied on as a guide for optimal treatment, but a three week course of [[rifampicin]] and [[doxycycline]] twice daily is the combination most often used, and appears to be efficacious;<ref name=Robichaud_2004 /><ref name="Maley2006">{{cite journal |author=Maley MW, Kociuba K, Chan RC |title=Prevention of laboratory-acquired brucellosis: significant side effects of prophylaxis |journal=Clin. Infect. Dis. |volume=42 |issue=3 |pages=433-4 |year=2006 |pmid=16392095 |doi=10.1086/499112}}</ref> the advantage of this regimen is that it can be taken by mouth and there are no injections, however, a high rate of side effects (nausea, vomiting, loss of appetite) has also been reported.<ref name="Maley2006"/>
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| ''B. melitensis'' }}
 
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| ''B. abortus'' }}
==Blue light study==
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| ''B. suis'' }}
In a study published in ''Science'' magazine in August of 2007, it was revealed that ''Brucella'' reacts strongly to the presence of the blue spectrum in natural light, reproducing at a great rate and becoming infectious. Conversely, depriving ''Brucella'' of the blue wavelengths dropped its reproductive rate by 90%, a result one of the co-authors called "spectacular."<!-- presumably with no pun intended.--><ref name="SciNEWS">[http://sciencenow.sciencemag.org/cgi/content/full/2007/823/2 "Deadly in the Daylight"] August 23, 2007 in ''ScienceNOW Daily News''.  Accessed September 8, 2007.</ref><ref name="SCIENCE">[http://www.sciencemag.org/cgi/content/abstract/317/5841/1090 "Blue-Light-Activated Histidine Kinases: Two-Component Sensors in Bacteria
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| ''B. ovis'' }}
"], August 24 2007, ''Science'' Vol. 317:5841, pp. 1090 - 1093  Accessed September 8, 2007.</ref>
! style="width: 120px;background: #4479BA" |{{fontcolor|#FFF| ''B. canis'' }}
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | Need to CO2
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | Production of H2S
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | -
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | Growth on basic fushin 0.002%
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | Growth on thionin 0.004%
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | +
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | Growth on thionin 0.002%
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | +
|-
| style="width: 120px;font-weight: bold;background: #DCDCDC" | Destroy with Tb phage
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | +
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | -
| style="background: #F5F5F5; text-align:center" | -
|-
|}


==References==
==References==
{{reflist|2}}
{{reflist|2}}


==External links==
[[Category:Disease]]
* [http://www.hpa.org.uk/infections/topics_az/zoonoses/brucellosis/menu.htm Brucellosis]
[[Category:Up-To-Date]]
 
[[Category:Pulmonology]]
*[http://www.genomesonline.org/search.cgi?colcol=all&goldstamp=ALL&gen_type=ALL&org_name1=genus&gensp=Brucella&org_domain=ALL&org_status=ALL&size2=ALL&org_size=Kb&gen_gc=ALL&phylogeny2=ALL&gen_institution=ALL&gen_funding=ALL&gen_data=ALL&cont=ALL&gen_country=ALL&gen_pheno=ALL&gen_eco=ALL&gen_disease=ALL&gen_relevance=ALL&gen_avail=ALL&selection=submit+search Brucella Genome Projects] (from [http://www.genomesonline.org Genomes OnLine Database])
[[Category:Hepatology]]
 
[[Category:Rheumatology]]
*[http://img.jgi.doe.gov/cgi-bin/pub/main.cgi?section=TaxonList&page=lineageMicrobes&genus=Brucella Comparative Analysis of Brucella Genomes] (at [[United_States_Department_of_Energy|DOE's]] [[Integrated_Microbial_Genomes_System|IMG system]])
[[Category:Nephrology]]
 
*[http://bbp.hegroup.org/ Brucella Bioinformatics Portal]
 
[[Category:Rhizobiales]]
[[Category:Gram negative bacteria]]
[[Category:Infectious Disease Project]]
 
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Latest revision as of 20:44, 29 July 2020

Brucellosis Microchapters

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Brucella

Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Alpha Proteobacteria
Order: Rhizobiales
Family: Brucellaceae
Genus: Brucella
Species

B. abortus
B. canis
B. melitensis
B. neotomae
B. ovis
B. suis

This page is about microbiologic aspects of the organism(s).  For clinical aspects of the disease, see brucellosis.

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Danitza Lukac, Vishal Devarkonda, M.B.B.S[2]

Overview

Human brucellosis is caused by four Brucellae species: B. abortus, B. canis, B. melitensis, and B. suis.[1]

Causes

Brucella species

Brucella species have been found primarily in mammals. [3] Brucellla species, with their host and degree of virulence is described below:[4]

Species Host Human Virulence
B. melitensis Goats, sheep, cattle, buffaloes, dogs and camels ++++
B. abortus Cattle, buffaloes, bison, dogs, elk, and horses ++/+++
B. canis Dogs +
B. suis Pigs and sheep +
B. ovis Sheep -

Tests to differentiate brucella species

Following tests may be used to differentiate between the different species of brucella.[5]

Test B. melitensis B. abortus B. suis B. ovis B. canis
Need to CO2 - + - + -
Production of H2S - + + - -
Growth on basic fushin 0.002% + + - + -
Growth on thionin 0.004% - - + + +
Growth on thionin 0.002% + - + + +
Destroy with Tb phage - + - - -

References

  1. ↑ "WHO" (PDF).
  2. ↑ Ryan KJ, Ray CG (editors) (2004). Sherris Medical Microbiology (4th ed. ed.). McGraw Hill. ISBN 0-8385-8529-9.
  3. ↑ Pappas G, Akritidis N, Bosilkovski M, Tsianos E (2005). "Brucellosis". N Engl J Med. 352 (22): 2325–36. doi:10.1056/NEJMra050570. PMID 15930423.
  4. ↑ "WHO" (PDF).
  5. ↑ "WHO" (PDF).
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