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Premium member Presentation Transcript Brucella : Brucella -Varun C N Slide 2: Small, Gram-negative coccobacilli Strict aerobes Non capsulate, non motile Obligate intracellular parasites The genus Brucella consists of seven species, some containing several biovars, differentiated on the basis of cultural, metabolic and antigenic characteristics. Oxidase and Catalase positive Capnophilic BSL-3 pathogen Brucellosis is a zoonosis 2 Varun C N- Brucella http://www.genomenewsnetwork.org/articles/09_02/weaponized.shtml Slide 3: Varun C N- Brucella 3 Important members of Brucella B. melitensis B. abortus B. suis B. canis Slide 4: Varun C N- Brucella 4 http://pathmicro.med.sc.edu/ghaffar/brucell03-2.jpg Brucella spp. are poorly staining, small gram-negative coccobacilli and are seen mostly as single cells and appearing like “fine sand” Slide 5: Varun C N- Brucella 5 http://medchrome.com/basic-science/microbiology/brucella-and-brucellosis/ Slide 6: Stephen H. Gillespie, Principles and Practice of Clinical Bacteriology Second Edition 6 Varun C N- Brucella Slide 7: Varun C N- Brucella 7 Antigens 1. Lipopolysaccharide The O-antigen contains several epitopes, including the A and M antigens The A epitope predominates in B. abortus strains 2. Outer Membrane Proteins They were first classified according to their apparent molecular mass into group 1 (88–94 kDa) group 2 (35–39 kDa) group 3 (25–31 kDa) 3. Cytoplasmic Proteins Stress proteins such as GroEL, GroES, DnaK and HtrA Bacterioferritin Lumazine synthetase L7/L12 ribosomal protein Slide 8: Varun C N- Brucella 8 Main somatic antigens: A and M The 3 main Brucella differ from one another in the amount of the 2 main antigen they have in common B.abortus (A:M=20:1) B.melitensis (A:M=1:20) B.suis (A:M=2:1) Slide 9: Varun C N- Brucella 9 Pathogenesis Intracellular Survival O-Polysaccharide Cu–Zn superoxide dismutase enzyme Inhibits de-granulation in WBC Brucellosis: Brucellosis is primarily a disease of animals and it affects organs rich in the sugar erythritol (breast, uterus, epididymis, etc.). The organism localizes in these animal organs and cause infertility, sterility, mastitis, abortion or resides as carriage. Humans in closed contact with infected animals Slide 10: Varun C N- Brucella 10 http://www.merinews.com/article/brucellosis-in-humans/15775025.shtml Slide 11: Varun C N- Brucella 11 Slide 12: Varun C N- Brucella 12 Clinical Manifestations: Acute brucellosis (influenza like syndrome) : Undulant fever (usually peaks in the evening and slowly returns to normal by morning) Headache, Limb and back pains are unusually severe, night sweating and fatigue are marked Anorexia, weakness, loss of weight, depression Slide 13: Varun C N- Brucella 13 Sub-acute brucellosis: It may follow acute brucellosis. Blood culture is less frequently positive. Skin test is positive. Chronic brucellosis: It is usually non bacteremic. Blood culture is rarely positive. Skin test and agglutination are strongly positive. Slide 14: Varun C N- Brucella 14 Acute unilateral scrotal swelling in a 27-year-old man with brucellosis http://www.medscape.com/viewarticle/441224_3 Slide 15: Varun C N- Brucella 15 Eurosurveillance, Volume 15, Issue 30, 29 July 2010 Slide 16: Varun C N- Brucella 16 Laboratory Diagnosis Specimen: Blood Urine, sputum, breast milk Lymph node biopsy Bone marrow aspirate Culture and isolation: Methods: Castaneda’s method Automated methods such as Bactec is best Culture: Liver infusion or glucose serum broth Sheep blood agar Trypticase soya broth Addition of bacitracin, polymyxin or cycloheximide makes media selective Slide 17: Varun C N- Brucella 17 Colonies of Brucella abortus Small pearly-white colonies of Brucella melitensis after prolonged culture on blood agar http://www.superstock.com/stock-photos-images/4102-22482 http://bestpractice.bmj.com/best-practice/monograph/911/resources/image/bp/1.html Slide 18: Varun C N- Brucella 18 Identification Do not ferment carbohydrate Catalase positive, Oxidase positive Strong Urease positive Reduce nitrate to nitrites IMViC ---- Standard agglutination test (SAT) It is a tube agglutination test in which equal volumes of serial dilution of patients and standard antigens are mixed. On incubation at 37 C a titre of more than 1:160 is considered as significant. SAT is done using standard antigens derived from B abortus strain 119 False negative reaction is seen in case of high dilutions. This is called as Prozone phenomenon . Cross reaction may be seen against E coli, V cholerae, Y enterocloitica, F tularensis etc… Slide 19: Varun C N- Brucella 19 Slide 20: Varun C N- Brucella 20 Slide 21: Varun C N- Brucella 21 Slide 22: Varun C N 22 Thank you for your kind attention You can also follow me at my blog. www.microboids.net You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.