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Created page with '===Overview=== *Important zoonoses worldwide *Cause chronic granulomatous diseases *6 species *Target reproductive organs of certain species *Infected animals act as reservoir …'
===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
*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]]
*Caprine and ovine brucellosis:
**Caused by ''B. melitensis''
**Goats more susceptible
**Abortion, orchitis in males, arthritis, hygromas
**May not have protective immunity following abortion
**Rose Bengal agglutination test and complement fixation test
**Test and slaughter where exotic
*Ovine epididymitis
**Caused by ''B. ovis''
**Epididymitis in rams and placentitis in ewes
**Reduced fertility in rams, sporadic abortion and peinatal mortality
**Venereal transmission
**Long latent period in rams following infection (present in semen 5 weeks after infection)
**Premating checks on rams - serological tests and scrotal palpation
**Testicular atrophy and swollen epididymis in chronically-infected rams
**Agar gel immunodiffusion test, complement fixation test and indirect ELISA
**Vaccination of young rams with ''B. melitensis'' vaccine or ''B. ovis'' bacterin
*Porcine brucellosis:
**Caused by ''B. suis''
**Prolonged bacteraemia
**Chronic inflammation in reproductive organs of boars and sows; also in joints and bones
**Routes of infection: ingestion or venereal
**Abortion, still birth, neonatal mortality, temporary sterility
**Boars excreting bacteria in semen may have testicular abnormalities or be normal
**Lameness, incoordination and posterior paralysis in joint and bone involvement
**Rose Bengal and indirect ELISA for diagnosis
**Test and slaughter where exotic
**Modified live ''B. suis'' vaccine
*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]]
*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
*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]]
*Caprine and ovine brucellosis:
**Caused by ''B. melitensis''
**Goats more susceptible
**Abortion, orchitis in males, arthritis, hygromas
**May not have protective immunity following abortion
**Rose Bengal agglutination test and complement fixation test
**Test and slaughter where exotic
*Ovine epididymitis
**Caused by ''B. ovis''
**Epididymitis in rams and placentitis in ewes
**Reduced fertility in rams, sporadic abortion and peinatal mortality
**Venereal transmission
**Long latent period in rams following infection (present in semen 5 weeks after infection)
**Premating checks on rams - serological tests and scrotal palpation
**Testicular atrophy and swollen epididymis in chronically-infected rams
**Agar gel immunodiffusion test, complement fixation test and indirect ELISA
**Vaccination of young rams with ''B. melitensis'' vaccine or ''B. ovis'' bacterin
*Porcine brucellosis:
**Caused by ''B. suis''
**Prolonged bacteraemia
**Chronic inflammation in reproductive organs of boars and sows; also in joints and bones
**Routes of infection: ingestion or venereal
**Abortion, still birth, neonatal mortality, temporary sterility
**Boars excreting bacteria in semen may have testicular abnormalities or be normal
**Lameness, incoordination and posterior paralysis in joint and bone involvement
**Rose Bengal and indirect ELISA for diagnosis
**Test and slaughter where exotic
**Modified live ''B. suis'' vaccine
*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]]