Bacteria

Brucellosis

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Brucellosis, Brucella abortus, Brucella suis, Brucella melitensis, Brucella canis

  • Epidemiology
  1. US Incidence <100 cases per year (0.34/100,000)
  • Causes
  1. Brucella abortus (cows)
  2. Brucella suis (pigs)
  3. Brucella melitensis (goats, camels)
  4. Brucella canis (dogs)
  • Pathophysiology
  1. Facultative intracellular Parasite
    1. Releases endotoxin when dies
  2. Infective dose: 10-100 organisms
  3. Incubation: 5-60 days
  • Transmission
  1. Zoonosis from animal exposure or infected animal products
    1. Tissue from Sheep in U.S.
    2. Unpasteurized milk
    3. Cow, pig, goat or sheep exposure
  2. Vaccine exposure
  3. No transmission person to person
  4. Enters via mucus membranes, broken skin, or inhalation
  • Risk Factors
  1. Veterinarians
  2. Farm workers
  3. Meat processing plants
  4. Travel or residence in endemic region
    1. Mediterranean
    2. India
    3. North Africa, East Africa
    4. Central Asia, South Asia
  • Symptoms
  1. Intermittent Fevers
    1. Undulating fever
    2. Temperature peaks in evening to 101-104
  2. Arthralgia especially sacroileitis (20-30%, up to 90% in some studies)
  3. Weakness
  4. Lassitude
  5. Weight loss
  6. Headache
  7. Sweating
  8. Chills
  • Signs
  1. Hepatosplenomegaly (20-30%)
  2. Cervical or Inguinal Lymphadenopathy (12-20%)
  3. Orchitis or Epididymitis (2-40%)
  4. Purpura (5%)
  • Differential Diagnosis
  1. Tularemia
  2. Psittacosis
  3. Rickettsia
  4. Visceral Leishmaniasis
  5. Human Immunodeficiency Virus (HIV)
  • Complications
  1. Meningitis
  2. Endocarditis
  • Labs
  1. Culture (Slow growing, fastidious organism)
    1. Blood Culture (70% sensitive in acute illness)
    2. Discharge Culture
    3. Bone Marrow Aspirate (90% sensitive in acute illness)
  2. Complete Blood Count
    1. Thrombocytopenia
    2. Granulopenia
    3. Leukopenia with relative Lymphocytosis
    4. Anemia
  3. Brucella Serology
  4. Brucella PCR
  5. Liver Function Tests (elevated in 30-60%)
  6. Bone Marrow Biopsy show Granuloma
  • Management
  • Non-localized
  1. Precautions
    1. Risk of relapse in 10% of cases
    2. See other references for neurobrucellosis and endocarditis
  2. Age <8 years old or pregnancy
    1. TMP-SMZ 5 mg/kg of TMP orally twice daily for 6 weeks AND
    2. Rifampin 15-20 mg/kg up to 600-900 mg orally daily for 6 weeks
  3. Age >8 years old and adults
    1. Doxycycline 100 mg orally twice daily for 6 weeks AND
    2. Gentamicin 5 mg/kg IV daily for 7 days AND
    3. Consider Rifampin 15-20 mg/kg up to 600-900 mg orally daily for 6 weeks
      1. May be used in place of Gentamicin
      2. For Spondyloarthropathy or Arthritis, use all 3 agents, with Rifampin with Doxycycline for 3 months
      3. When combined with Doxycyline and Gentamicin improves clearance rates without relapse
        1. Vrioni (2014) Antimicrob Agents Chemother 58:7541-4 [PubMed]
  • Prevention
  1. See other references for Post-exposure Prophylaxis
  • Course
  1. Weeks to months
  • Prognosis
  1. Case Fatality <5% treated
  • References
  1. (2016) Sanford Guide to Antibiotics, IOS app accessed 4/14/2016
  2. (1998) Medical Management of Biological Casualties
    1. U.S. Army Medical Research Institute of ID