Difference between revisions of "Brucella species"

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<big><center>[[Infectious agents and parasites|'''BACK TO INFECTIOUS AGENTS AND PARASITES''']]</center></big>
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#REDIRECT[[:Category:Brucella species]]
<big><center>[[Bacteria|'''BACK TO BACTERIA''']]</center></big>
 
 
 
 
 
*''B. abortus'' occasionally in [[Joints - inflammatory#In Cattle|arthritis of cattle]]
 
 
 
 
 
*Isolated from closed cases of [[Bursae and Tendons - inflammatory#Poll Evil and Fistulous Withers|Poll Evil and Fistulous Withers]]
 
 
 
===Overview===
 
 
 
*Important zoonoses worldwide
 
*Cause chronic granulomatous diseases
 
*6 species
 
*Target reproductive organs of certain species
 
*Infected animals act as reservoir of infection
 
*Organisms can remain viable in moist environment for months
 
*Cause undulant fever in humans
 
 
 
 
 
===Characteristics===
 
 
 
*Small, non-moltile, Gram negative coccobacilli
 
*Facultatice intracellular pathogens
 
*Modified Ziehl-Neelsen positive - clusters of red coccobacilli on smears
 
*Aerobic and capnophilic
 
*Catalase positive; oxidase and urease positive except for ''Brucella ovis'' 
 
*Some species require enriched media for growth
 
*Non-haemolytic
 
*Smooth colonies of ''B. abortus, B. melitensis'' and ''B. suis'' are small, glistening, blue and translucent after incubation for 3-5 days, and become opaque with age
 
*Rough colonies of ''B. ovis'' and ''B. canis'' are dull, yellow, opaque and friable
 
*Slide agglutination with speicific antisera detect important antigens
 
*''B. abortus'' lysed by specific bacterophages
 
*Oxidative metaboloic rates can differentiate species
 
 
 
 
 
===Pathogenesis and pathogenicity===
 
 
 
*Penetrate nasal, oral or pharyngeal mucosa
 
*Phagocytosed and carried to regional lymph nodes
 
*Survive and multiply in cells of the reticulo-endothelial system
 
*Inhibit lysosome-phagosome fusion
 
*Lymph nodes enlarge (lymphatic and lymphoreticular hyperplasia) and inflammation is induced
 
*Surviving organisms spread to other organs (liver, spleen, placenta) and cause granulomatous reactions
 
*Eythritol is a growth stimulant and attracts the bacteria to the bovine placenta
 
*Infection of foetus and abortion
 
 
 
 
 
===Clinical disease===
 
 
 
 
 
 
 
 
 
===Diagnosis===
 
 
 
 
 
 
 
 
 
===Control===
 
 
 
*Serological testing of milk (Milk Ring Test) and beef cattle (Rose Bengal Plate Test)
 
*Serological tests detect anti-lipopolysaccharide antibodies
 
*LPS antigen present in virulent as well as some vaccine strains therefore vaccination may confuse serological testing
 
*False positives due to cross-reaction with LPS in other bacteria
 
*Vaccination:
 
**Strain S19, a live vaccine, stimulating a cell-mediated immune response; vaccination of young animals; interferes with serological testing
 
**Newer RB51 vaccine has no LPS O-antigen therefore not detcted by serological tests
 
**Live attenuated ''Brucella melitensis'' vaccine to protect sheep and goats against ''B. melitensis''
 
*Test and slaughter program has eradicated Brucellosis in the UK
 

Latest revision as of 21:06, 10 May 2010