Brucella Ultimate

8/8/2019 Brucella Ultimate

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Brucella



Brucella spp.

y Gram negative, coccobacilli

y Facultative, intracellular organism

y Environmental persistence

Temp, pH, humidity

Frozen and aborted materials

y Multiple species



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



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



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



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,



V irulence

Lipopolysaccharide

Contain 2 antigenic determinants

A & M

B. abortus A: M = 20:1

B. melitensis M : A = 20:1

B. suis - intermediate



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.



y Antigenic cross reaction occurs with V . cholerae,

E.coli 0:116, 0:157, Salmonella, Ps. maltophila, Y.

enterocolitica, F. tularensis



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



y Organism carried to LN & sequestrated in

reticuloendothelial systems liver, spleen,

bone marrow

Phagocytosed by macrophages providing a safe

haven

Macrophages rupture eventually



Brucella inside the macrophage



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



y potential agent of bioterrorism

delivered affectively by aerosol & able tosurvive both in soil & water for weeks

Providing both immediate & delayed period of

infectivity



Granuloma formation



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



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



Disease in Humans



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



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



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



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



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



Laborator y diagnosis

y Culture

y Grams

y Serological

y molecular



Coccobacillar y form



y Specimen: blood & bone marrow

y ( 70% & 90% positivity rate )



y High index of suspicion

y H/O occupational exposure & exotic travel,

ingestion of uncooked food



y Biosafety level 3 organism

y Avoidance of procedure known to generate

aerosol





y Strict aerobic

y Capnophilic (B. abortus)

y Temp- 37c(20-40)

y pH 6.6 to 7.4



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



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



Blood agar



Blood agar



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



Prozone phenomena



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



y Positive titres also seen in cholera, tularemia &

Yersinia infection

y Cross reacting agglutinins removed by agglutinationabsorption test & also by mercaptoethanol



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



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



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



Treatment

y To Treat current infection

y Prevent relapse

y Surgical intervention



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.



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



Prognosis

y May last days, months or years

y Recovery is common

y Disability is often pronounced

y About 5% of treated cases relapse

y Case-fatality rate: <2% ( untreated)

Endocarditis caused by B. melitensis

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Brucella Ultimate