Unit 3: Brucella Flashcards
What is the morphology of the genus Brucella?
gram-negative small rods or coccobacilli
Describe the growth on culture of the genus Brucella.
slow growing (2-5 days), forms small colonies, grows well on BAP, may need some CO2
What is identification of specific Brucella species based on?
urease, oxidase, CO2 requirement, H2S, growth in the presence of dyes, agglutination
What is the genus Brucella generally susceptible to?
chemical disinfectants
What is the general pathogenesis of the Brucella genus?
The organism pass from the point of entry to the lymphatics, multiply in the regional lymph node and then enter the bloodstream. They travel to the parenchymatous organs and other tissues. They are primarily intracellular in macrophages with development of granulomatous foci or nodules in the lymph nodes, liver, spleen, bone marrow, and testes
What is Brucella abortus the cause of?
abortion in cattle and undulant fever in humans
What does Brucella abortus require for growth?
CO2 on primary isolation - growth is stimulated by erythritol
Where is Brucella abortus endemic and in what species?
in the middle east in cattle, goats, horses, camels, and others
What is Brucella abortus excreted in?
genital secretions, colostrum, or mil from recently infected cows or carrier animals that abort or calve
What are the two infectious routes of Brucella abortus?
- ingestion of food and water contaminated with uterine discharges or urine or ingestion of milk
- Penetration of skin and mucous membranes
What is the pathogenesis of Brucella abortus in cows that are pregnant (6 months +)?
the organism localizes in the placenta causing abortion, due primarily to circulatory disturbance, and sometimes sterility
What does Brucella abortus cause in bulls?
epididymitis and orchitis which leads to sterility or decreased fertility
True or False: Calves maintain Brucella abortus infection.
false
What is the significance of erythritol in Brucella abortus infection?
it is a sugar alcohol present in the placenta and testes of susceptible species - it provides stimulation of growth in these tissues
What humans are susceptible to Brucella abortus?
lab workers, veterinarians, slaughterhouse workers, and farmers
What is a major source of human infection of Brucella abortus?
unpasteurized milk
What is undulant fever characterized by?
profuse perspiration, joint and back pain
Where may Brucella abortus localize in humans?
liver, lymph nodes, or bone
How do you treat Brucella abortus infection in humans??
tetracycline and/or streptomycin for at least one month
Brucella abortus causes disease in _____ and _____ similar to that in cattle.
sheep and goats
What does Brucella abortus cause in horses?
fistulous withers or poll evil
What is used in the United States to vaccinate against Brucella abortus?
RB51 - a B. abortus rough strain (lacks O antigen)
What does accidental exposure of RB51 in humans require?
20-day-post-exposure treatment with doxycycline
When should heifer calves be vaccinated with RB51?
at 3-10 months of age
True or False: There is a State-Federal cooperative control program in the U.S for Brucella abortus.
True
What are the 3 components of the State-Federal Cooperative control program for Brucella abortus?
- Blood test cattle either at the sale barn, slaughter plant, or pre-sale replacement heifers and cows going from one farm or state to another
- Eliminate all cattle with positive titers
- Calfhood immunization is required in a few states. Calves are less susceptible to infection but can still be infected
What is the card test for Brucella abortus?
it is a field test that uses 1 serum dilution and a stained antigen
What is the ring test for Brucella abortus?
it tests for immunoglobulin in the milk of cows and is run 1 to 4 times per year on each dairy herd depending on state/federal agreement
What is the cause of Malta fever?
Brucella melitensis
Where is Brucella melitensis infection widespread?
in countries surrounding the Mediterranean, central Asia, around the Arabian Gulf and Latin America
What species does Brucella melitensis infect in endemic areas?
sheep, camels, and horses
How do humans become infected with Brucella melitensis?
by eating unpasteurized goat milk
Disease in goats due to Brucella melitensis is very similar to that caused by what in cattle?
Brucella abortus
True or False: Brucella suis is host restricted to swine.
False
How is Brucella suis transmitted?
via ingestion of contaminated feed or water or venereal
What may infection of Brucella suis cause in swine?
sterility, birth of a stillborn or weak pigs, and focal abscessation in organs
What can Brucella suis cause in cattle?
spondylitis or lameness
How do you diagnose Brucella suis infections?
agglutination tests
How do control a Brucella suis infection?
isolate and slaughter infected swine herds and sanitize the premises and restock after 2 months
What does Brucella ovis cause?
Contagious epididymitis in rams and may cause abortion and decreased fertility in ewes
True or False: There is a State-Federal Cooperative control program in the US for Brucella ovis.
False
What is Brucella canis’ growth inhibited by?
10% CO2
What does Brucella canis cause?
persistent bacteremia, generalized lymphadenitis, splenitis, embryonic deaths, and late term abortions
epididymitis and testicular atrophy in males
How is Brucella canis transmitted?
it is passed in large numbers by aborting females and infects other dogs via oral and conjunctival routes
The organism can be transmitted to males that breed with infected females and vice versa
What is the distribution of Brucella canis?
it is most common in large kennels and in the southeastern United States and is common in other countries especially where feral dogs are a problem
How do you diagnose a Brucella canis infection?
culture and a rapid slide agglutination test (RSAT)
Is there treatment for Brucella canis?
long term antibiotics have been tried but it is not usually practiced
How is Brucella canis infection conrolled?
test and eliminate positive animals
What animals are Brucella pinnipediae and Brucella cetaceae isolated from?
marine animals
What does Brucella pinnipediae and Brucella cetaceae cause?
abortion in marine animals
