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VMS 2006 > Brucella > Flashcards

Brucella Flashcards

1
Q

What does Brucella cause?

A

Abortion in animals and foodborne zoonosis for humans

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2
Q

Where was brucella first discovered?

A

In small cocci in the spleen

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3
Q

What is the basic microbiology of brucella?

A
  • Gram negative
  • Small coccobacilli
  • Aerobic, Capnophillic (thrive in high CO2), Catalase +
  • Faculative intracellular
  • Has environmental persistence
  • Non-Sporulating
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4
Q

What are the 6 classical species of Brucella?

A
  1. B. abortus
  2. B. melitensis
  3. B. suis
  4. B. canis
  5. B.ovis
  6. B. neotomae
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5
Q

What species are smooth/ possess the O-polysaccharide?

A

B. abortus, B. melitensis & B. suis

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6
Q

What species are naturally rough/ do not produce OPS?

A

B. ovis & B. canis

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7
Q

What type of Brucella are more pathogenic?

A

Smooth

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8
Q

What is the taxonomy of Brucella?

A

Phylum: α-Proteobacteria
* Order: Rhizobiales
* Family: Brucellaceae
* Genus: Brucella

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9
Q

What has brucella derived from?

A

soil dwelling plant associate

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10
Q

What is important about ruminant abortion

A
  • Only in the last trimester
  • they only abort once from the infection
  • next pregnnacy they excrete the bacteria- milk/ calf may be infecred
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11
Q

Where is the significant shedding of brucella in ruminants?

A

Through milk

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12
Q

How is brucella transmissed?

A
  • Shared grazing
  • Importation of animals
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13
Q

Why does brucella not effect human pregnancies?

A

Humans do not produce the hormone erythitol

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14
Q

How does brucella cause abortion in a pregnant animal carrying it?

A
  1. Erythitol is produced by placental cells in the final trimester
  2. Brucella is attracted to the placenta-due to the erythitol
  3. Invasion of the placenta via erythropathogenic cells
  4. Causes an inflammatory response -> tissue damage -> abortion
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15
Q

What are the clinical signs of brucella in pigs?

A
  • Similiar to ruminants
  • may see swollen joints and tendon sheaths, lameness and incoorrdination
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16
Q

How do we control brucella in animals?

A

Culling rather than Treating

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17
Q

What are the clinical signs of brucella in horses?

A
  • Vague lameness
  • ‘fistulous’ withers
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18
Q

How many chromosones does Brucella have and what are their total size?

A
  • 2 chromosones
  • total size = 3.3 Mbp
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19
Q

What can release large quantities of Brucella into the environment?

A

Abortion or live birth from an infected animal

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20
Q

What is the most significant brucella symptom in males?

A

Orchitis

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21
Q

In what herds is their most likely to be ‘extreme’ abortion storms?

A

Naive herds, may be abortion storms of up to 50%

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22
Q

How may Brucella be passed on into humans?

A
  • Conjunctiva or Broken skin comes into contact with infected tissue
  • May be ingested/ e.g raw milk
  • Inhalation of infectious aerosols
  • Inoculation with vaccines
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23
Q

What is the average incubation of brucella?

A

7-21 days to several months

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24
Q

What are the most common symptoms of Brucella in humans?

A
  • Flu-Like, e.g anorexia, fatigue, weight-loss
  • Hepatosplenomegaly, Lymphadenopathy
  • primarily a febrile disease
25
Q

How is Brucella Treated?

A

Antibiotic treatment- doxycycline, streptomycin

26
Q

What usually causes death in humans?

this is rare <2%

A

endocarditis, meningitis

27
Q

What percentage of treated cases relapse?

A

Around 5%

28
Q

Where does Brucella mainly reside?

aka what cell

A

within non-professional and professional phagocytes such as
macrophages & form Brucella Containing Vacuoles (BCVs)

this makes it invisible to the immune system

29
Q

How does the Type IV secretion system work?

A
  • Injects effector proteins into the cytoplasm cell
  • T4SS is crucial for establishment
    of the replicative niche –
    an endoplasmic reticulum
    (ER) derived vacoule.
  • Brucella T4SS mutants are
    highly attenuated
30
Q

Give 5 ways you could diagnose Brucella

A
  1. Serological testing
  2. Milk testing
  3. Culture Abortion Products
  4. Bacteriological identification
  5. Tissue collected post-mortem

rose-bengal test is the most common

31
Q

What two infectious agents may resemble Brucella?

A
  1. Coxiella
  2. Chlamydia
32
Q

What growth media would you use to grow Brucella?

A

Farrels medium containing horse serum
* 10% CO2
* Selective Enrichment used for blood

33
Q

What are the best ways we can control Brucella?

A
  • Pasteurisation of milk
  • Vaccination of cattle, sheep and goat in enzootic areas
  • Eradication testing and culling
  • Continued surveillance of milk and blood
  • Epidemiological tracing
34
Q

What category is Brucella in terms of Biological Warfare?

A

Category B
* Moderately easy to disseminate
* causes moderate morbidity and low mortality

35
Q

What does Brucella form when it resides within non-professional and ‘professional’ phagocytes?

A

Brucella Containing Vacuoles

36
Q

What is a ‘Brucella Containing Vacuole’?

A

They are invisible to the immune system and therefore known as stealth pathogens

37
Q

What type of Phagocytes can kill Invading Brucella?

A

Pre-Activated Macrophages, e.g with IFN-Y

38
Q

What Virulence Factors does Brucella lack?

A
  • Capsules
  • Adhesins
  • Fimbriae
  • Excreted Toxins
39
Q

What is the function of the T4SS?

A
  • Injects effector proteins into the cytoplasm cell
  • T4SS is crucial for the establishment of the replicative niche
  • The Brucella T4SS are highly attenuated
40
Q

What is the most widely used screening test for Brucella?

A

Rose Bengal Plate Test

41
Q

How may you diagnose Brucella?

A
  • Serological testing
  • Testing of Milk
  • Smear Examination
  • Culture of abortive products
  • Tissues collected post-mortem
  • Bacterial Identification
42
Q

How could you diagnose Brucella using microscopy?

A
  • Using smears of milk, vaginal discharge or placenta
  • Stamps’ modified Ziehl-Neelson Method
43
Q

What are Brucella resistant to?

A

Brucella are not truly acid-fast but are resistant to decolourisation by weak acids

44
Q

What other infectious agents may resemble brucella?

A
  • Coxiella Burnetti
  • Chlamydia
45
Q

How would you culture Brucella?

A
  • Due to slow growth- Selective media are usually required on primary culture
  • 10% CO2
  • Selective media such as Farrels medium
  • Serum dextrose agar is generally recommended for subculture
  • Selective enrichment for blood
46
Q

How would you diagnose Brucella using blood typing?

A
  • Serology is based on the reference OPS
  • Growth on media-containing dyes
  • CO2 is a requirement, H2S is produced
47
Q

What media containing dyes are acceptable for Brucella?

A
  • Thionin
  • Basic Fuchsin
48
Q

What molecular tests are available for Brucella?

A
  • Tandem repeats/ Variable Repeats
  • Multilocus sequence typing
  • PCR based on mobile elements
49
Q

What part of the Brucella is immunogenic?

A

LPS Surface antigen

50
Q

In what secretions are Brucella antibodies present?

A

In Serum and Milk

51
Q

What are important issues that should be brought up in the brucella vaccination programme?

A
  • Cost
  • Sensitivity
  • Specificity
52
Q

Why should you not use live vaccines in pregnant animals?

A

Live vaccine strains retain residual virulence

53
Q

What do you need to be able to safely handle brucella?

A
  • Safety cabinets
  • Negative pressure
  • Fumigation
54
Q

What is the WHO risk group 3?

A

pathogens that pose a high risk to the worker but only a low risk to the community

55
Q

What agar is generally only recommended for subculture?

A

Serum dextrose agar

56
Q

What organisms share epitopes and may cause a cross-reaction with brucella?

A
  • Yersinia enterocolitica
  • E.Coli 0:157
57
Q

How do you reduce an area from high brucella prevalence to low brucella prevalence?

A

Cattle: B. abortus S19 (smooth) or RB51(rough)
* Sheep & Goats: B. melitensis Rev1 (smooth)
* No vaccine for swine
* No vaccine for humans (all remain virulent in humans)

58
Q

Why should you not use the vaccines in pregnant animals?

A

if the live vaccine strains contain residual virulence

VMS 2006 (23 decks)

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