brucella mahadi ppt
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BRUCELLA
Sharq Elneil College
School of Medical Laboratory Sciences Department of Microbiology
Medical Bacteriology course
Mr.Mahadi Hassan Mahmoud Bsc, Msc, MIBMS Microbiology
Historical Background
1897 A.E. Wright ; pathologist in British
army - developed agglutination test.
What is the source?
“Mediterranean Fever Commission” 1904
1905 Zammit; Maltese physician - Goats were the source of infection. 1897 E. Bang; Danish veterinarian -described intracelular pathogen causing
abortion in cattle named “Bacillus abortus”.
1918 A. Evans; American microbiologist -made the connection between Bacillus
abortus and micrococcus melitensis & named it Bacteriaceae.
Historical Background
1920 Meyer and Shaw suggested BRUCELLA
1914 Mohler isolated organism from
liver & spleen of Pigs--B.suis. 1957 B. neotome, 1963 B. ovis, 1966
B. canis
Historical Background
Aerobic, Gram-negative bacilli
Appear as cocci, coccobacilli and short bacilli
Non-motile, non-capsulate
Optimum temp. >> 37oC
Facultative intracellular parasites
Essentially pathogens of goats, Cattle, sheep and pigs
Causative agents of Brucellosis
(typical zoonosis) worldwide
Also known as Malta, Mediterranean or undulant fever
Important species
B. melitensis >> goats & sheep
B. abortus >> cattle
B. suis >> pigs
Important: All 3 species can infect man and domestic animals
Brucella species gram-negative bacilli
Brucella abortus
Transmission
Zoonosis affecting domestic animals.
Concentrated in milk, urine, genital organs.
ROUTES OF TRANSMISSION
Oral : unpasteurised milk & products raw milk or meet.
Respiratory: lab workers.
Skin: accidental penetration or abrasion - at risk farmers & veterinarians.
Other routes:
Conjunctival, Blood transfusion, Transplacental, ? person to person.
PATHOGENESIS
Incubation period: 10-30 days
Symptoms may be delayed for months
Enter the body through: Skin abrasions, mucous membranes of the
alimentary or respiratory tracts and sometimes the conjunctivae>> reach the blood through regional lymphatics.
Symptoms may vary without the fluctuating temperature to act as guide.
Bacteria localize in various parts of the reticulo-endothelial system resulting in complications in any part of the body.
Symptoms include: malaise, low-grade fever, lassitude, insomnia, irritability and swelling around the joints.
LABORATORY DIAGNOSIS
1. Blood Culture
Specimen
Blood (10 ml volumes)
Inoculate
Blood culture tubes or bottles (glucose-serum broth)
Incubate in 10% CO2
Cultures should be retained for at least 6-8 weeks before being discarded as negative
Brucella melitensis colonies
2. Serological Tests
Standard agglutination test
Mercaptoethanol test
Complement fixation test
Coobs’ test
3. Brucellin Skin Test
Laboratory WBC (N) or . monocytosis
ESR of little help
Blood cultures
slow growth = 4 weeks
new automated system BATEC identifies he organism 4-8 days
more recent (BACT/ALERT) - 2.8 days
PCR
Biochemical tests
Gram stain: Gram negative cocco bacilli
Biochemicals:
Catalase
Oxidase
Dye inhibition test
Laboratory Diagnosis
Serology Main laboratory method of
diagnosis Serum agglutination test -
most widely used measures agglutination for
IgG, IgM, IgA 2ME - break sulf-hydrile bonds
in IgM polymer - no agglutination
which level is diagnostic ?? 1 : 160 - non endemic area 1 : 320 - endemic area SAT - false negative Prozone Blocking antibodies
Other tests: coombs, ELISA, CFT, FTA
Prognosis
Preantibiotic era
Mortality 2% mainly endocarditis
Morbidity
High with B. melitensis
Nerve deafness
Spinal cord damage
Antimiocrobial S.T
Combination of streptomycin and tetracycline or rifampicin and doxycycline
Vaccination of young cattle (6-8 months)
Pasteurization of milk or milk products
Eradication by compulsory testing animals and slaughtering positive reactors.
THANK YOU FOR ATTENTION