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Sharq Elneil CollegeSchool of Medical Laboratory Sciences Department of Microbiology Medical Bacteriology course BRUCELLA 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
Historical Background 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
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 speciesgram-negative bacilli
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 DIAGNOSIS1. 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’ test3. 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
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.