LECTURE - Brucella Flashcards
Agents of ________, a zoonotic disease with bioterrorism/bioweapon potential
brucelllosis
B. abortus
cattle
B. melitensis
goats and sheep
B. suis
swine
B canis
dog
Characteristics of Brucella species
- non-motile
- gram neg coccobacilli
- strict aerobe
- obligate mammalian pathogen; facultative intracellular (can grow in cells but don’t have to); only found in animal (not environment growing)
- special nutritional requirements = thiamine, niacin, biotin; Blood agar ok
- 2-3 days to grow at 37 C
- biosafety level 3 to handle!!
- CDC category B agent
- causes granulomas
economically important disease of domesticated animals
Brucellosis ; worldwide!
Where is brucellosis more common
found worldwide but more common in countries that do not have good standardized and effective public health and domestic animal health programs
- high risk = Mediterranean Basin, South & Central America, Eastern Europe. Asia, Africa, Caribbean, Middle East
village cheeses
unpasteurized cheese from high endemic areas for Brucellosis may present risk for tourists
main species infecting Bison
Brucella abortus
- Tuberculosis and brucellosis = AB
Brucella
organotropism for pregnant uterus
cattle; B. abortus
Brucella
organotropism for mammary glands
goats and sheep; B. melitensis
four ways Brucella can get in
- most common = ingestion of either contaminated dairy products, undercooked meats, etc.
- abraded skin = vets, Abattoir workers
- conjunctivae = by aerosols or fingers (rubbing eyes; hunter)
- inhalation of aerosols = slaughterhouse procedures, lab accidents, vet manipulations
main virulence factors of Brucella spp.
- LPS = 100 x less endotoxic than other LPSs but impairs innate immune response (complement binding)
- PCS = molecular mimicry; phosphatidylcholine synthase
- CGS = prevents phagosome-lysosome fusion
- VirB is a type IV secretion system (injection needle); effector proteins modify host cell function; inhibit the phagosome-lysosome function
- can survive in macrophages**
unusual growth p Brucella spp.
unipolar growth
- asymmetric division
….
clinical manifestations of Brucella spp.
- malaise
- chills
- fever (remittent)
- headache
- profuse sweats (esp. during the morning after a night fever)
- neuropsychiatric (depression, anxiety or insomnia); don’t feel right = problem to diagnosing Brucella unless vet or something
- *organism can end up all over body**
diagnosis of Brucellosis
- lab = blood cultures esp at a time of fever spikes; Casteneda bottles (sloped agar; layered over with broth)
- quantitative serology (based on Abs patient will produce overtime); ELISA/EIA tests
- clinical = occupation, raw milk, fresh cheese, travel, symptoms, signs
- course of disease
diagnosis of Brucellosis
- lab = blood cultures esp at a time of fever spikes; Casteneda bottles (sloped agar; layered over with broth)
- quantitative serology (based on Abs patient will produce overtime); ELISA/EIA tests
- clinical = occupation, raw milk, fresh cheese, travel, symptoms, signs
- course of disease
serological tests for Brucella
- Rose Bengal Test (RBT); agglutination; can quantitate; sensitive
- serum agglutination test (SAT); sensitive
- complement fixation test (CFT) = more specific; carried out on all RBT pos samples
T or F. Brucella organisms live inside macrophages in organ tissue
T! start to fuse together as they attempt to wall off organisms invading but eventually, fibrin will form around the whole process = granuloma (giants cells of fused macs infected by organism); Th1 response needed to eliminate organisms
Brucella as a facultative intracellular pathogen
- live inside macs in organ tissue
- inhibit phagosome-lysosome fusion
- form granulomas
- Th1 response needed to eliminate intracellular organisms
Treatment and prevention of Brucellosis
- Tetracyclin (works intracellularly) with rifampin or streptomycin
- attenuated live vaccine available for cattle on;y
- elimination (destruction of infected animals) is the most effective prevention
model for evasion of lysosomal killing through expression of virulence factor (Brucella)
- entry dependent on LPS and BvrR/BvrS regulatory system on surface
- LPS + phosphatidylcholine synthase (PCS) and cyclic beta 1-2 glucan (CGS) = intracellular trafficking
- interaction & fusion with ER elements leading to bacterial replication dependent on VirB type IV secretion system; since virB-effective mutant fails to sustain fusion-proficient interactions with the ER and ultimately fuses with lysosomes
