Brucella Flashcards
Brucella Gram____? Shape?
Gram negative, small, coccobacilli (more coccoid) Pairs or clusters
Brucella Motile/Non-motile?
Non-Motile
Brucella Capsulated?
Non-encapsulated
Brucella Flagellated?
No flagella
Brucella Spore-forming?
Non-spore forming
Brucella Name the dominant surface antigens in LPS in rough versus smooth colonies
Rough: “R” antigen Smooth: “A” abortus or “M” melitensis antigens
Brucella What is significant about the cell wall?
Peptidoglycan layer = thicker than other Gram negative (modified acid fast stains for diagnosis)
Brucella Distribution?
Worlwide
Brucella Stable in environment?
No, obligate pathogen Survives 4 months in milk, urine, water, damp soil but NEEDS MAMMALIAN HOST
Brucella Often chronic or acute infections?
Mainly chronic infections
Brucella Target site
Reticuloendothelial system & genital tract Abortion & epididymitis/orchitis
Brucella Pathogenic species
*B. melitensis, B. abortus, B. suis* B. canis, B neotomae, B. ovis B. cetaceae, B. pinnipediae
Brucella Reportable?
YES REPORTABLE
Brucella Virulence factors
Cell Wall Erythritol Outer membrane proteins Superoxide dismutase & catalase T4SS
Brucella Erythritol role
4 carbon sugar alcohol *Allantoic fluid factors* (stimulates growth) Preferential location for reproduction & mammary glands
Brucella Omp (Outer membrane protein)
Stimulate delayed type hypersensitivity
Brucella Superoxide dismutase and catalase function
Defense against oxidative killing
Brucella T4SS function
Intramacrophage survival
Brucella Resistance factors
Survives freezing & thawing Survives in milk & other fluids Pasteurization kills it
Brucella Diversity
Genome very stable Different species vary in host preference & degree in virulence
Brucella What type of colonies are more virulent? Smooth or rough?
Smooth more virulent than rough Depends on polysaccharide side chain in LPS
What factors change Brucella host preference and virulence?
CO2 requirements H2S production Urease production Susceptible to different concentrations of certain dyes Susceptibility to bacteriophage (Tbilisi phage)
How does Brucella abortus differ from other strains?
B. abortus is susceptible to Tbilisi phage, others are resistant
Brucella Zoologic & Geographic reservoirs
Obligate parasite Host preference (some broad range) Survival time in environment depends on temperature & moisture
B. abortus
Cattle Smooth colonies, virulent Bison, camels, yaks
B. suis
Swine Smooth colonies, virulent Hares, reindeer
B. melitensis
Goat & Sheep Smooth colonies, virulent Camelids
B. neotomae
Wood Rat Smooth colonies, virulent
B. ovis
Sheep
B. canis
Dogs
Brucella Modes of transmission
Ingest cow/goat milk In utero (direct) Venereal Urine (dogs) Insects (maybe, minor)
Describe Brucella’s venereal transmission
Male sex gland infections Dissemination occurs without lesions Common in swine, sheep, dogs
Brucella Pathogenesis
Penetrates intact mucosa–> Macrophage–> survives –> Regional lymph node –> hematogenous dissemination & localization in reticulo-endothelial system & repro tract –> Abortions
How do Brucella species survive inside macrophages?
T4SS, Superoxide dismutase, catalase
How do Brucella species cause abortions?
Interference with fetal circulation / placentitis Endotoxin Fetal stress / Inflammation
What type of inflammation is shown in the picture?
Granulomatous inflammation!
What can cause Brucella infections to move extra-genitally? (Disseminate)
Prolonged bacteremia
Brucella Pathology
Grossly visible lesions in placenta Intercotyledonary thickening with yellow gelatinous fluid Necrotic cotyledon with thick brown exudate Aborted edematous fetus Male genitalia
Describe Brucellosis in males
Palpable enlargement of epididymus Increase neutrophils in semen (acute cases) Orchitis Scrotal dermatitis in dogs Results: decrease fertility, sometimes sterility
Describe orchitis from Brucellosis in males
Necrosis in testicular parenchyma with pus, prostatitis, fibrinopurulent, seminal vasculitis
What is shown in the picture? What species caused it?
Necrotic cotyledons in aborted material. B. melitensis
Brucella Disease Pattern Female reproductive tract
Abortion (most commonly) Retained placenta Mastitis (goats)
Brucella When will it cause cattle to abort?
~5month gestation
Brucella When will it cause swine to abort?
At any time
Brucella When will it cause dogs to abort?
~50 days gestation
Brucella Repeat abortions or lasting immunity?
Females usually abort once Acquired immunity