Brucella Flashcards
Classification of Brucella.
Family: Brucellaceae
Genus: Brucella
Species: B. melitensis, B. suis, B.melitensis, B.melitensis
Describe classification of brucella.
Family: Brucellaceae
Genus: Brucella
Species: Many but know these: B. melitensis, B. suis
List general characteristics of brucella. (capsule,spores,motility,gram test, aerobicity and biochemical tests)
•Pleomorphic Gram-negative bacilli(short or coccobacilli)
• Non-sporeforming
• Non-motile
•Non-capsulated
•Obligate aerobes
•Oxidase, catalase and urease positive.
Explain transmission of brucella.
ZOONOSES
Infection in humans arises from:
Direct or indirect contact with infected animals
Consumption of contaminated meat or dairy products
Entry via:
1. Mucous membrane (droplets)
2. Broken skin
3. Ingestion (relatively common compared to the rest)
List the virulence factors.
.Lipopolysaccharide
•Inhibits phagosome fusion and lysosome destruction -> intracellular survival
•Inhibits complement deposition
•Outer membrane proteins
•Type IV secretion system •Allows pathogen to reach endoplasmic reticulum and replicate
•Superoxide dismutase, catalase •Defense against oxidative burst activity -> intracellular survival
Primary cell target?
Macrophages
it is a facultative intracellular pathogen
Describe the pathogenesis of brucella.
• Brucella first invade the host cells
• form Brucella-containing vacuoles (BCVs)
• undergo fusion with the lysosome in a controlled manner
• In this step, about 90% of the Brucella are degraded, and the remaining 10% survive
• the BCV traffic to and reach the endoplasmic reticulum (ER)and
• establish the replicative site
• after ER replication, the Brucella traffic toward the autophagy-like vacuoles
• survive within these compartments and finally,
• leave the host cells to promote cell-to-cell spreading
Whats the main clinical manifestation in brucella?
Brucellosis/Undulant fever
What are the levels of brucellosis?
Acute-fever and malaise; INTERMITTENT WAVES OF FEVER
Subacute- febrile illness
Chronic- Internal organ damage
List the complications of brucella.
nervous
cardiovascular
Bone and joint involvement
What specimen is used for diagnosis?
Blood
Infected tissue
It is highly contagious
What culture medium is used in diagnosis?
Culture medium: Tryptone soya(tryptic soy)
biphasic medium:Castenada
Describe the appearance of culture.
Colonies — small, smooth, convex, non-haemolytic
Biochemical tests?
Oxidase positive
Catalase positive
Urease positive
What antibiotics are used?
Rifampin
Doxcycline
Prevention techniques?
•Animal immunization-Eradication of infected animals
• No human vaccine available
•Post-exposure prophylaxis for high-risk individuals
•Avoid unpasteurized dairy products
