Test 2- Brucella Flashcards
Brucella
Gram–
Small
Non-motile
Coccobacilli
Culture: +
Obligate symbiotic, resistent
Obligate pathogen
Facultative intracellular
Reportable disease
Species
- Species
- B. melitensis, several animal species, mainly goat and sheep
- B. abortus, cattle
- B. suis, swine (hare, reindeer, caribou)
- B. canis, Dog
- etc
All of the brucella species have…
a high genetic homology, which makes it difficut to distinguish
International epidemiological context
B. melitensis: principal cause of human brucellosis No vaccines
Many countries eliminated B. abortus from cattle
Wildlife reservoirs, including marine-
B. melitensis: principal cause of human brucellosis No vaccines
Many countries eliminated B. abortus from cattle
Wildlife reservoirs, including marine This is why it has been very hard to get rid of
Falsepositiveserology(Y.enterocoliticaO9)
Facultative intracellular: carriers
Spread mainly by females animals Abortion
Fetus and especially placenta contains a huge amount of bacteria
Can spread via dogs and horses
False positive serology(Y.enterocoliticaO9)
Facultative intracellular: carriers
Spread mainly by females animals
Abortion- the aborted fetus is full of brucella
Fetus and especially placenta contains a huge amount of bacteria
Can spread via dogs and horses
Brucella abortus
Symptoms:
Infection
Mucosae
Oral
Wounds (upon handling contaminated meat)
Spread to regional lymphonodus
Further spread to other lymphonods, where it is safe from the immune system and then it goes to the TARGET ORGANS- only when it is in the target organs then the serology will be positive)
No symptoms- spread is via intracellular in macrophages– 1 to 6 weeks Incubation period
Brucella abortus
Pathogenesis
Target organs
Target organs
Reproductive organs
Uterus-fetus
Udder
Male reproductive organs
Articulations
Tendon sheath
Synovial bursa
Brucella abortus
Pathogenesis: Uterus + fetus
Placentoma & multiplication- Excretion and spread to bovines humans
Fetus & multiplication-
Abortion
Premature birth
Normal partution but calf is carrier
Pathogenesis: Udder
Subclinical mastitis
Excretion and spread
Diagnosis on milk samples
———– Antibodies
———–antigens
Farm status
Symptoms (human infection)
Acute bacteremic phase
Chronic phase (can take many years)
Intermittent fever
Duration: 3-4 weeks
A febrile period:3-4weeks
Long term
Weakness
Malaise
Headache
Jointandmusclepains
Enlargedlymphonodus
Enlargedliverandspleen Eventuallyosteomyelitis
Virulence
No capsule
No flagella (genetic code deficient)
Cell wall
Smooth colonies (Higher virulence )
———- Zoonotic more important species B.melitensis,B.abortus,B.suis
————- Not a stable phenotype, dissociation to R (mixed) (unfavorable growth conditions)
—————B. ovis and B. canis
————-Lacking the O-polysaccharide
What is different about the cell wall of brucella?
Cell wall (cont.)
Thicker PG than other Gr-
Erythritol
Responsible for preferential location
Reproductive organs
Mammary gland
Immunity
Antibodies
——--Come late
Cellular immunity
———-Early
Note
Facultative intracellular
Spread intracellular
Only when in organs antibodies are formed
Carriers
When cellular Immunity is not capable of killing all intracellular bacteria
———– Bacteria are intracellular
When immunity goes down (Pregnancy)
Bacteria
- ——– Start multiplication
- ———-are released from the cells
———–Abortion or transfer to fetus
Vaccination
Need for both humoral and cellular immunity
———- AroC mutants and DnaK mutants
Diagnosis
SAW or SAT: Slow Agglutination Test or Slow Agglutination of Wright.
Rose Bengal test simple, rapid slide-type agglutination assay, stained B. abortus suspension and plain serum
CFT- Complement fixation test
ELISA
IFN-γ-
Skin test
Bacteriology
How to grow B. abortus
B. abortus
Primary growth needs 10-20% CO2
B. abortus and B. suis produce H2S
Primary isolation: 4-7 days
Monoclonal antibodies
Farrell’s medium/ modified Thayer-Martin’s medium
Chocolate agar, horse blood (nicotinamide adenine dinucleotide (NAD))
eventually supplemented with Gr+ spectrum antibiotics and colistin if sample is contaminated like in abortions. Care what species (≠ susceptibility)
Specific commercial agars (eg. Brucella agar)
Brucellosis CMI Skin Test
Brucellergen (Skin) Test
- not an OIE recommended test
- often slight positive skin reactions - herd test
- not widely used- very hard to read
•EU regulation
(Proposed by the Scientific Committee)
- in the context of False Positive Serological Reactions
- discriminating method between FPSR and True Positive
Brucellosis CMI- IFN- gamma
- intrinsic values not known
- control possible, without any delay - complementary to serology
- costly
- need of culture
—— blood test
Diagnosis
Test strategy should be adapted to the countries plan for elimination of the agent
Note that there is a major interference when Yersinia enterocolitica O9 is present
Note that also B. suis can give false positive infections (contact wild boars)
Transient positive serology
Brucella suis
Small non-motile Gram-negative coccobacilli
Needs enriched media for growth
Obligate symbiotic
Obligate pathogenic
Resistant in the environment (in organic material) but does not withstand direct sunlight
- REPORTABLE
Eradicated in domesticated swine (including US, Canada, most EU countries)
Still present in wildlife
Reservoir for b. suis
wild boar (Sus scrofa scrofa)
Care: hunters!
B. suis General
5 biovars (based on biochemical testing)
5 biovars (based on biochemical testing)
Biovar1 and 2:
(reservoir in hares)
Biovar3:
Most pathogenic for pigs
Biovar4:
mainly in reindeer, caribou
Less pathogenic for pigs (seldom found)
Biovar5:
Brucellosis in mice
Genetically closer to the marine Brucella species
VariousB. suis biovarshavebeen reportedoccasionally in cattle, small ruminants, horses, dogs and other spillov er hosts
1-3 Biovars are the most pathogenic of pigs
Symptoms of B. suis
Reproduction system: abortion, orchitis, infertility
Arthritis
Tendovaginitis
Bursitis
Osteomyelitis
Note: swine can be infected with B. abortus, B. melitensis, B. canis but these infections do not result in clinical symptoms- but they can give false positive reactions
Has been weaponized
Zoonotic, hunters!
More pathogenic than B. abortus
Acute infection; duration couple of months
Temperature raises and falls intermittent
Sweating
Chills
General malaise
Weakness Joint pain
Complications: osteomyelitis Chronic
Localisation
Necrosis and pus
Pathogenesis of B. suis
Introduction Skin
M ucosae
XXX
1. regional lymph nodes (in leucocytes)
2. bacteremia after 1-7 weeks (in macrophages and neutrophils), duration 1 wk- 34 mths (mean 5 wks)
3. localization with abscess formation Lymphnodes
Reproductiveorgans Liver
Spleen
joints
Immunity to B. suis
Humoral
Cellular +++ (facultative IC)
However, carriers
In macrophages
Insufficiently activated MF
Not destroyed by cytotoxic T-lc
Diagnosis Brucellosis in wild boar, serology
Care
Contact with bovines: B. abortus
Yersinia enterocolitica O9
Brucella suis, wild boars
Serological tests only of value at farm level
Many cross reactions:
Y. enterocolitica O9 (and others)
Francisella
Campylobacter
Salmonella
Pasteurella
E. coli O157
Brucella melitensis Brucella ovis
Sheep and goat
Similar to B. abortus in bovines
Mainly in subtropical and Mediterranean countries (Malta fever)
B. melitensis, zoonotic: worse than B. abortus (Malta fever)
B. ovis: not zoonotic
Brucella canis
Need rich media for growth
Primary isolation up to 4 weeks!
Do not have O antigens
Obligate parasitic
Obligate pathogen
Resistant in the environment in organic material
Zoonotic
Symptoms of Brucella canis
Long bacteremia, no fever!
Lymphadenitis
Late abortion
Vaginal discharge
Epididymitis
Scrotum dermatitis
Atrophia testicularis
Prostatitis
STD
Dx and treatment of Brucella canis
Diagnosis
Bacteriology
Serology
Care: many false positive and false negative results
Treatment
Difficult
Long antibiotic treatment
Frequent recurrences after stop of treatment (IC)
Consider euthanasia (zoonosis!)
