Brucella
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The document provides a detailed overview of Brucella, a genus of small, non-motile, aerobic, gram-negative coccobacilli responsible for brucellosis, a significant zoonotic disease. It includes information on the cultural characteristics, biochemical reactions, pathogenicity, types of infections, immunological response, laboratory diagnosis methods, prophylactic measures, and treatment options. A clinical case is presented to illustrate the disease's impact, with emphasis on diagnosis and management strategies.
Brucella
- 2. INTRODUCTION Small, non motile, aerobic, Gram negative coccobacilli David Bruce (1886) Zoonosis Mediterranean fever, Malta fever, Undulant fever
- 3. Brucellosis an Important Zoonotic Disease 3
- 4. SPECIES OF BRUCELLA Brucella melitensis Brucella abortus Brucella suis Brucella canis Brucella ovis Brucella neotomae
- 5. CULTURAL CHARACTERISTICS Strict aerobes B. abortus is capnophilic Serum dextrose agar Serum potato infusion agar Trypticase Soy agar Bacitracin, Polymyxin and Cycloheximide makes them selective Erythritol
- 6. BIOCHEMICAL REACTIONS Non fermentative Catalase + Oxidase + Urease + Nitrates are reduced to Nitrites Indole, MR, VP - Negative
- 7. RESISTANCE Destroyed at 60ºC in 10 minutes 1% Phenol in 15 minutes Killed by Pasteurisation Survive in soil and manure for several weeks Viable for 10 days in refrigerated milk, 1 month in ice cream and 4 months in butter. Sensitive to acids Meat – many weeks Sunlight
- 8. ANTIGENIC STRUCTURE A and M antigens Antigenic cross reaction exist with E. coli, Salmonella, Pseudomonas maltophila, Yersinia enterocolitica, Francisella tularensis & Vibrio cholorae Superficial L antigen – Vi antigen
- 9. CLASSIFICATION CO2 requirement, H2S production, sensitivity to dyes (Basic fuchsin and Thionin) Agglutination with monospecific sera Oxidative metabolic tests Phage lysis Tblisi bacteriophage B. suis lysed at 10,000 RTD, B. abortus at 1 RTD B. melitensis – Not lysed B. suis – American strain (H2S) - British strain
- 10. PATHOGENICITY Intracellular pathogen Reticuloendothelial system Lipopolysaccharide acts as a virulence factor Brucellae enter through wound, conjunctiva, inhalation or ingestion Incubation period is 10 – 30 days Multiply in lymph nodes Spill over into blood stream Prediliction to placenta (erythritol)
- 11. Types of Infection Latent infection Acute or Subacute Brucellosis Chronic Brucellosis
- 12. ACUTE BRUCELLOSIS Undulant fever Prolonged bacteremia and irregular fever Muscular and articular pain Asthmatic attacks Nocturnal drenching sweats Exhaustion Anorexia Constipation Nervous irritability Chills
- 13. CHRONIC BRUCELLOSIS No bacteremia Low grade infection with periodic exacerbations Hypersensitivity Sweating, Lasitude, Joint pain No pyrexia Illness lasts for years
- 14. IMMUNITY Cell mediated Activated macrophages T helper cells TNF α,γ Interleukins 1 and 12 Tissue reaction to brucella consists of granuloma formation with epithelial cells, giant cells, lymphocytes and plasma cells Granuloma heals with fibrosis and sometimes become calcified
- 15. LABORATORY DIAGNOSIS Culture Blood Bone marrow Lymph nodes CSF Urine Abscess, Sputum, Breast milk, Vaginal discharge & Seminal fluid Serology Delayed Hypersensitivity – type skin tests Animal inoculation – Straus reaction
- 16. BLOOD CULTURE Castaneda method Trypticase Soy broth 5 – 10% CO2 6 – 8 weeks Positive in 30 to 50% of cases
- 17. STANDARD AGGLUTINATION TEST(SAT) Tube agglutination test Titre of 160 or more is significant Blocking or Non agglutinating antibodies Blocking effect removed by prior heating at 55ºC for 30 min or 4% Saline Coomb’s test Positive in cholera, Tularemia, Yersinia, Immunisation 2- mercaptoetanol
- 18. DETECTION IN MILK AND INFECTED ANIMALS Immunofluorescence Milk Ring Test Brucella antigen ( killed B. abortus stained with hematoxylin) 70ºC for 40 – 50 min Blue ring at the top leaving the milk unstained Whey agglutination Test Rose Bengal Card Test Rapid Plate Agglutination Tests
- 19. PROPHYLAXIS Checking dairy animals for Brucellosis Slaughter of infected animals Certified Brucella free herds Pasteurisation Brucella abortus strain 19 vaccine
- 20. TREATMENT Doxycycline (45 days) + Streptomycin (2 weeks) Cotrimoxazole + Rifampicin or Gentamicin
- 21. CLINICAL CASE A 50 year old farmer presented with a history of intermittent fever for the previous 3 weeks. He complained of loss of appetite and nausea but there was no other specific complaints. The farmer attended to his cattle and sold the milk at the market nearby. On examination, no specific signs for the fever were found. Detailed laboratory test revealed only anaemia. Given his occupational history blood culture and SAT were carried out. The culture was negative and SAT titres were >1:1280 Diagnosis? Treatment?
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