Difference between revisions of "Brucella species"
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| Line 37: | Line 37: | ||
===Pathogenesis and pathogenicity=== | ===Pathogenesis and pathogenicity=== | ||
| + | *Brucellae that lack outer membrane LPS (rough colonies) are less virulent than those which possess it | ||
*Penetrate nasal, oral or pharyngeal mucosa | *Penetrate nasal, oral or pharyngeal mucosa | ||
*Phagocytosed and carried to regional lymph nodes | *Phagocytosed and carried to regional lymph nodes | ||
| − | * | + | *Smooth organisms survive and multiply in cells of the reticulo-endothelial system |
*Inhibit lysosome-phagosome fusion | *Inhibit lysosome-phagosome fusion | ||
| + | *Superoxide dismutase and catalase production may resist oxidative killing | ||
*Lymph nodes enlarge (lymphatic and lymphoreticular hyperplasia) and inflammation is induced | *Lymph nodes enlarge (lymphatic and lymphoreticular hyperplasia) and inflammation is induced | ||
*Surviving organisms spread to other organs (liver, spleen, placenta) and cause granulomatous reactions | *Surviving organisms spread to other organs (liver, spleen, placenta) and cause granulomatous reactions | ||
| − | *Eythritol is a growth stimulant and attracts the bacteria to the | + | *Eythritol is a growth stimulant and attracts the bacteria to the placenta of cattle, sheep, goats and pigs; also found in mammary gland and epididymis, targets for brucellae |
*Infection of foetus and abortion | *Infection of foetus and abortion | ||
| + | *May localise in joints or intervertebral discs in chronic infections | ||
| Line 54: | Line 57: | ||
===Diagnosis=== | ===Diagnosis=== | ||
| + | *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 | ||
| + | ===Control=== | ||
| − | |||
| − | |||
| − | |||
| − | |||
| − | |||
*Vaccination: | *Vaccination: | ||
**Strain S19, a live vaccine, stimulating a cell-mediated immune response; vaccination of young animals; interferes with serological testing | **Strain S19, a live vaccine, stimulating a cell-mediated immune response; vaccination of young animals; interferes with serological testing | ||
Revision as of 17:37, 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
- Brucellae that lack outer membrane LPS (rough colonies) are less virulent than those which possess it
- Penetrate nasal, oral or pharyngeal mucosa
- Phagocytosed and carried to regional lymph nodes
- Smooth organisms survive and multiply in cells of the reticulo-endothelial system
- Inhibit lysosome-phagosome fusion
- Superoxide dismutase and catalase production may resist oxidative killing
- 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 placenta of cattle, sheep, goats and pigs; also found in mammary gland and epididymis, targets for brucellae
- Infection of foetus and abortion
- May localise in joints or intervertebral discs in chronic infections
Clinical disease
Diagnosis
- 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
Control
- 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