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Brucellosis

Brucellosis. Prepared by: Dr Mostafavy SN Department of Pediatric Infectious Disease Isfahan University of Medical science. Etiology. Brucella spp. Melitensis : severe disease Abortus Suis Canis: infrequent Gram negative coccobacilli Intracellular

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Brucellosis

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  1. Brucellosis Prepared by: Dr Mostafavy SN Department of Pediatric Infectious Disease Isfahan University of Medical science

  2. Etiology • Brucella spp. • Melitensis : severe disease • Abortus • Suis • Canis: infrequent • Gram negative coccobacilli • Intracellular • Zoonosis: lives in breast, genitourinary, and blood of the host( humans accidental host)

  3. Transmission • Conjunctiva or broken skin • Farmers • Ranchers • Abattoir workers • Veterinarians • Slaughters • Ingestion of unpasteurized dairy products • Inhalation • Stables • Laboratories

  4. Pathogenesis • Inoculation to susceptible host • Ingestion by phagocytic cells • Multiply within PMNs • Disseminationto RES and joints • Replicationin organs • Cell mediated immunity( humoral) • Recovery+/- ABs

  5. Clinical manifestations • Incubation period: 1-4wk( to several mo.) • Insidious onset, more benign in children • Classic triad • Fever, arthritis( sacroilliac and large lower limbs), (hepato)splenomegaly • Nonspecific complaints • Anorexia, sweats, fatigue, weight loss • Occasional complications • Neurobrucellosis, osteomyelitis, endocarditis • Relapse within 6-12 mo

  6. Diagnosis • Medical history • Nonspecific tests • Culture • Serological tests • PCR

  7. Medical history • Occupation • Consumption of unpasteurized dairy product • Family history • Affected animals • Travel to endemic area

  8. Nonspecific tests • WBC/ diff (usually normal to low) • ALT/ AST( minor disturbances is common) • CSF analysis: lymphocytic pleocytosis, increased protein, decreased glucose • Synovial analysis: WBC< 15,000, Lymphocytic predominance

  9. Culture • Definite diagnosis • Any fluid: blood, bone marrow, liver biopsy, synovial, CSF • The sensitivity in blood is lower( 15-70%) than bone marrow(80-90%) • Bone marrow in pts with severe cytopenia, FUO, or negative serology • Time consuming( 7th-21st day), shorter in Bactec system • Inform lab personnel

  10. Humoral responses in brucellosis • IgM appear earlier than IgG • But IgM persists for months to years after therapy • IgG decline to low levels after therapy • Rising IgG suggest relapse, reinfection, or complication

  11. Serological tests • Agglutination tests: • Wright test( slide, tube) • Coombs Wright test • 2 Mercapto-Ethanol test • ELISA tests

  12. Wright test • Two types: • Standard: (in tubes), report titers • Rose Bengal: on plates, rapid screening test, sensitivity> 99% • Measures antibodies against LPS (no B. canis) • The mainstay diagnosis of acute brucellosis: simple, low cost, and reliable (90% sensitive)

  13. Wright test • Seroconversion or 4 fold increase of the titers over >2 weeks is the definite test • Titers >1:160 in endemic and >1:80 in non-endemic areas is highly suggestive • False positive: cross-reaction with other bacteria • False-negative: early infection , immuno suppression, prozone phenomenon, blocking antibodies, complicated cases

  14. Slide Agglutination Test

  15. Coombs Wright Test • Addition of anti-human globulin to SAT tubes • Titers > 1/320 considered as positive • Can detect blocking antibodies • Helpful in highly suspected cases with negative SAT • 7% false-negative results

  16. Coombs Wright Test

  17. 2 Mercapto Ethanol test • Addition of 2ME to brucella SAT tubes • 2ME makes IgM inactive • Positive test( >1/80 ) is evidence of active infection

  18. ELISA tests • Simple, rapid, and reliable but expensive • Measures IgM, IgG, and IgA • Useful in complicated, relapsed or reinfection cases

  19. Treatment • Disease: • Doxycycline(Cotrimoxazole in < 8yr) for 6 wk+ • Gentamicine for 14 days or rifampine for 6 wk • Complications: • Doxycycline(Cotrimoxazole in < 8yr) for 6 mo+ • Gentamicin for 14 days+ • Rifampin for 6 mo in adults and chidren< 8 year

  20. Prevention • Education • Wearing gloves, masks, goggles if dealing with infected animals/ tissues • Avoiding consumption of raw dairy products • Immunization of animals • Eradicate reservoir

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