Difference between revisions of "Brucella species"
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| Line 12: | Line 12: | ||
*Important zoonoses worldwide | *Important zoonoses worldwide | ||
*Cause chronic granulomatous diseases | *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 | ||
| Line 18: | Line 23: | ||
*Small, non-moltile, Gram negative coccobacilli | *Small, non-moltile, Gram negative coccobacilli | ||
*Facultatice intracellular pathogens | *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=== | ===Pathogenesis and pathogenicity=== | ||
Revision as of 17:28, 17 May 2008
- B. abortus occasionally in arthritis of cattle
- Isolated from closed cases of 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