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Brucella : 

Brucella -Varun C N

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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

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Varun C N- Brucella 3 Important members of Brucella B. melitensis B. abortus B. suis B. canis

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Varun C N- Brucella 4 Brucella spp. are poorly staining, small gram-negative coccobacilli and are seen mostly as single cells and appearing like “fine sand”

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Stephen H. Gillespie, Principles and Practice of Clinical Bacteriology Second Edition 6 Varun C N- Brucella

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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

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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)

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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

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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

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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.

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Varun C N- Brucella 14 Acute unilateral scrotal swelling in a 27-year-old man with brucellosis

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Varun C N- Brucella 15 Eurosurveillance, Volume 15, Issue 30, 29 July 2010

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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

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Varun C N- Brucella 17 Colonies of Brucella abortus Small pearly-white colonies of Brucella melitensis after prolonged culture on blood agar

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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…

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Varun C N 22 Thank you for your kind attention You can also follow me at my blog.

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