Brucella : Brucella -Varun C N Slide 2: Small, Gram-negative coccobacilli
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
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. 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
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
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.suis (A:M=2:1) Slide 9: Varun C N- Brucella 9 Pathogenesis
Cu–Zn superoxide dismutase enzyme
Inhibits de-granulation in WBC
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.
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
Urine, sputum, breast milk
Lymph node biopsy
Bone marrow aspirate
Culture and isolation:
Automated methods such as Bactec is best
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
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.