Post on 09-Apr-2018
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Brucella spp.
y Gram negative, coccobacilli
y Facultative, intracellular organism
y Environmental persistence
Temp, pH, humidity
Frozen and aborted materials
y Multiple species
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Introduction
y Brucellosis is a zoonosis, primarily affecting goats, sheep,
cattle, buffaloes, pigs, etc
y Humans contract infection from infected animals
y Major species causing human brucellosis are
Brucella melitensis
B. abortus
B. suis
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The Many Names of Brucellosis
Human Disease
y Malta Fever
y Undulant Fever
y Mediterranean Fever
y Rock Fever of Gibraltar
y Gastric Fever
Animal Disease
y Bangs Disease
y Enzootic Abortion
y Epizootic Abortion
y Slinking of Calves
y Ram Epididymitis
y Contagious Abortion
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Morpholog y
y Coccobacilli or short rods arranged singly or in short
chains
y Non motile
y Non capsulated
y Non sporing
y Non acid fast
y Bipolar staining can be seen
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Culture characters
y Strict aerobes
B. abortus is capnophilic
y Optimum temperature
370C (20 400C)
y pH
6.6 7.4
y Growth media
Grows on simple media but growth is scanty
Addition of serum or liver extract help in better growth
Serum dextrose agar, serum potato infusion agar,
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V irulence
Lipopolysaccharide
Contain 2 antigenic determinants
A & M
B. abortus A: M = 20:1
B. melitensis M : A = 20:1
B. suis - intermediate
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y Smooth / rough antigenic variation is : decreased
expression of gene encoding glycosylation of LPS
y Organism in smooth phase possess smooth type LPS
prevents intracellular killing by PMN presumably by
inhibiting lysosomal degranulation & respiratory burst
associated with PMN activation.
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y Antigenic cross reaction occurs with V . cholerae,
E.coli 0:116, 0:157, Salmonella, Ps. maltophila, Y.
enterocolitica, F. tularensis
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Pathogenesis
y Route : direct contact from animal
ingestion of contaminated meat
inhalation of aerosolized organismPhagocytosed by PMN : production of superoxide
dismutase, blocks toxic radicals
inhibition of degranulation of the granules of myeloperoxidase system
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y Organism carried to LN & sequestrated in
reticuloendothelial systems liver, spleen,
bone marrow
Phagocytosed by macrophages providing a safe
haven
Macrophages rupture eventually
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Brucella inside the macrophage
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y Released bacteria hematogenous seeding to
other organ leading to protean clinical
manifestation
y Tissue reaction - granuloma formation with
epithelial cells, giant cells, lymphocytes, plasma
cells
y Predilection for placenta d/t erythritol
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y potential agent of bioterrorism
delivered affectively by aerosol & able tosurvive both in soil & water for weeks
Providing both immediate & delayed period of
infectivity
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Granuloma formation
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Transmission to Humans
y Conjunctiva or broken skin contacting infected tissues
Blood, urine, vaginal discharges, aborted fetuses, placentas
y Ingestion
Raw milk & unpasteurized dairy products
Rarely through undercooked meat
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Transmission to Humans
y Inhalation of infectious aerosols
Pens, stables, slaughter houses
y Person-to-person transmission is very rare
y Incubation varies
7-21 days to several months
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Disease in Humans
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Human Disease
y Can affect any organ or organ system
y All patients have a cyclical fever
y Variability in clinical signs
Headache, weakness, arthralgia, depression, weight loss,
fatigue, liver dysfunction
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Human Disease
y 20-60% of cases
Osteoarticular complications
ÙArthritis, spondylitis, osteomyelitis
y Hepatomegaly may occur
y Gastrointestinal complications
y 2-20% of cases
Genitourinary involvement
ÙOrchitis and epididymitis most common
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Human Disease
y Neurological
Depression, mental fatigue
y Cardiovascular
Endocarditis resulting in deathy Chronic brucellosis is hard to define
Length, type and response to treatment variable
Localized infection
y Blood donations of infected should not be accepted
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A cute Brucellosis Clinical f inding (decreasing order of frequenc y)
y Fever >37c
y Joint pain
y Low backache
y Night sweat
y Cough, breathlessness,
hemoptysis
yTesticular pain, scrotal swellingburning micturition
y Pain abdomen, vomiting
y Jaundice
y Headache
y Fatigue
y Papule
y Convulsion
y Splenomegaly
y Hepatomegaly
y Lymphadenopathy
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Clinical spectrum
y Osteoarticular infection
y CNS ( neuro-brucellosis )
y Respiratory tract infection
y GIT / hepatobiliary
y Genitourinary tract infection
y Cardiovascular infection
y Ocular infection
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Laborator y diagnosis
y Culture
y Grams
y Serological
y molecular
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Coccobacillar y form
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y Specimen: blood & bone marrow
y ( 70% & 90% positivity rate )
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y High index of suspicion
y H/O occupational exposure & exotic travel,
ingestion of uncooked food
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y Biosafety level 3 organism
y Avoidance of procedure known to generate
aerosol
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y Strict aerobic
y Capnophilic (B. abortus)
y Temp- 37c(20-40)
y pH 6.6 to 7.4
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y Solid media- Serum dextrose agar, serum potato infusion
agar, trypticase soy agar, tryptose agar ( in MacConkey it
doesnt grow )
y Antibiotic supplements- bacitracin, polymyxin,
cycloheximide
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y Liquid media uniform, older culture produce powderyor viscous deposits
y Solid media- small, moist, translucent & glistening
y Erythritol & liver extracts stimulating growth
y Takes 4 -6 week
y BACTEC : 4 7 days
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Serological test
Standard agglutination test :
y tube agglutination test
y Serial dilution of patients serum & standardized antigen ( killedsuspension of standard strain of Br. abortus)
y Incubated 37c for 24hr or 50c for 18hr
>160 titre is positive
Titre tends to decline after acute phase of reaction
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Prozone phenomena
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y Selective IgG measured by addition of 2 - mercapto
ethanol which inhibits IgM
y IgM produced in 7-10 days after clinical infection,gradually declines & switch over occurs to class IgG
y
Rise in titre more imp than single high titre
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y Positive titres also seen in cholera, tularemia &
Yersinia infection
y Cross reacting agglutinins removed by agglutinationabsorption test & also by mercaptoethanol
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y Enzyme immunoassay
detects IgM, IgG, IgA against w hole B. abortus cell, B.
abortus smooth LPS, B. abortus protein extract & smoothLPS from B. melitensis as solid phase antigen
As sensitive & more specific than SAT
Others : complement fixation test, microscopicagglutination test, latex agglutination test
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In animal :
y Same methods also applicable
Fluorescent stained smears of biopsy samples from
pathological specimen
Rapid agglutination test
Rose Bengal card test
Milk ring test
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Diagnosis in Humans
y Isolation of organism
Blood, bone marrow, other tissues
y Serum agglutination test
Fourfold or greater rise in titer
Samples 2 weeks apart
y Immunofluorescence of organism in clinical specimen
y PCR
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Treatment
y To Treat current infection
y Prevent relapse
y Surgical intervention
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y Relapse occurs in nearly 30 % cases
y
Same therapy given for prolonged duration
y General condition & body weight is more
reliable indicator than serological markers
y IgG by SAT detected upto 2 yr.
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Prevention
y Control in domestic animals by mass vaccination
B. abortus strain 19 vaccine, B melitensis strain Rev 1
vaccine
y Protective clothings & gloves during handling still
birth/ product of conception & cultures
y Pasteurization of milk