|
|
| (11 intermediate revisions by 3 users not shown) |
| Line 1: |
Line 1: |
| − | ===Overview=== | + | {{frontpage |
| | + | |pagetitle =Brucella species |
| | + | |pagebody = The ''Brucella'' bacteria are Gram negative coccobacilli that cause important zoonoses worldwide. |
| | + | |contenttitle =Content |
| | + | |contentbody =<big><b> |
| | + | <categorytree mode=pages>Brucella species</categorytree> |
| | + | </b></big> |
| | + | |logo =bugs-logo copy.png |
| | + | }} |
| | | | |
| − | *Important zoonoses worldwide
| + | [[Category:Bacterial Organisms]] |
| − | *Cause chronic granulomatous diseases
| + | [[Category:Zoonoses]] |
| − | *6 species
| + | [[Category:Gram_negative_bacteria]] |
| − | *Target reproductive organs of certain species
| + | [[Category:Coccobacilli]] |
| − | *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
| |
| − | *Facultative 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 - Anatomy & Physiology|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===
| |
| − | [[Brucella abortus]]
| |
| − | [[Brucella melitensis]]
| |
| − | [[Brucella suis]]
| |
| − | | |
| − | | |
| − | | |
| − | *Canine brucellosis:
| |
| − | **Caused by ''B. canis''
| |
| − | **Rough therefore lower virulence - mild or asymptomatic infections
| |
| − | **Abortions, decreased fertility, reduced litter sizes, neonatal mortality
| |
| − | **Orchitis and epididymitis causing infertility in male dogs
| |
| − | **Infertility may be permanent if chronic infection
| |
| − | **Slide agglutination, ELISA, agar gel immunodiffusion
| |
| − | **Neuter infected animals
| |
| − | | |
| − | *Human brucellosis:
| |
| − | **Susceptible to ''B. abortus, B. suis, B. melitensis'' and ''B. canis''
| |
| − | **Transmission via contact with secretions from infected animals
| |
| − | **Routes of infection: skin abrasions, inhalation, ingestion
| |
| − | **Unpasteurised milk source of infection
| |
| − | **Undulant fever - fluctuating pyrexia, malaise, fatigue, muscle and joint pains, osteomyelitis
| |
| − | **Can become chronic
| |
| − | **''B melitensis'' and ''B. suis'' cause most severe infections
| |
| − | **Antimicrobials
| |
| − | | |
| − | ===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
| |
| − | *Modified Ziehl-Neelson stains reveal organisms in samples from cotyledons, uterine discharge and foetal abomasal contents
| |
| − | *PCR for detection in tissue
| |
| − | *Brucellin for intradermal testing for ''B. abortus''
| |
| − | *Enriched media for isolation
| |
| − | *Complement fixation test
| |
| − | *Indirect and competitive ELISA
| |
| − | *Serum agglutination test
| |
| − | *Antiglobulin test
| |
| − | | |
| − | | |
| − | ===Control===
| |
| − | | |
| − | *Test and slaughter program has eradicated bovine brucellosis in the UK
| |
| − | *Vaccination of heifers against ''B. abortus'' in endemic regions:
| |
| − | **Strain S19, a live attenuated vaccine, stimulating a cell-mediated immune response; vaccination of young animals; interferes with serological testing
| |
| − | **45/20 bacterin vaccine less effective
| |
| − | **Newer RB51 vaccine has no LPS O-antigen therefore not detected by serological tests and gives good protection
| |
| − | *Live attenuated ''Brucella melitensis'' vaccine to protect lambs and kids against ''B. melitensis''
| |
| − | [[Category:Bacteria]][[Category:Zoonoses]][[Category:Gram_negative_bacteria]] | |
