Updated: 6/1/2018

Francisella tularensis

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Snapshot
  • A 34-year-old man presents to the emergency room for acute-onset fever, pain in the eyes, and ulcer. He has not been to the physician in years, so his past medical history is unknown. He currently works at an angora rabbit farm and interacts with the animals daily. He reports being bit recently on his forearm, where there is now a lesion. On physical exam, he is febrile. He has severe conjunctival injection bilaterally and has multiple 1-2-cm tender cervical lymph nodes. On his left forearm, there is a 1-cm ulcer with elevated edges.
Introduction
  • Classification
    • Francisella tularensis
      • an aerobic gram - coccobacilli
    • transmission
      • hosts include ticks, rabbits, and deer flies
      • bites from exposed animals
      • inhalation of organism
  • Epidemiology
    • incidence
      • rare
    • demographics
      • south-central United States
    • risk factors
      • exposure to small mammals (rabbits, voles, muskrats, etc.)
  • Pathogenesis
    • inoculation of the skin or mucous membranes leads to spread of organism to the lymph nodes and other organs
    • inhalation may result in pulmonary disease
  • Associated conditions
    • ulceroglandular tularemia (most common)
    • typhoidal tularemia
    • pulmonary tularemia
      • may accompany both ulceroglandular (< 50% of cases) or typhoidal (80% of cases) tularemia
  • Prognosis
    • symptoms arise acutely < 1 week after exposure
    • patients with pneumonia have the highest mortality
Presentation
  • Symptoms
    • ulceroglandular
      • headache
      • painful conjunctivitis
      • pharyngitis
    • typhoidal
      • nausea
      • vomiting
  • Physical exam
    • high fever
    • ulceroglandular
      • tender maculopapular rash initially
      • lesion may ulcerate with a raised border
      • tender lymphadenopathy
    • typhoidal
      • hepatomegaly
      • splenomegaly
    • pneumonia
Imaging
  • Chest radiography
    • indication
      • suspected pulmonary involvement
    • findings
      • pulmonary infiltrates
      • hilar lymphadenopathy
      • pleural effusion
Studies
  • Labs
    • culture is hazardous
    • positive titers on serology
      • diagnostic
  • Making the diagnosis
    • based on clinical presentation, risk factors, and serology
Differential
  • Cat-scratch disease
    • distinguishing factor
      • lymphadenopathy with papular, pustular, or vesicular lesions without ulceration at the site of inoculation
  • Brucellosis
    • distinguishing factor
      • often presents with osteoarticular disease, such as osteomyelitis or arthritis
Treatment
  • Medical
    • aminoglycosides
      • indication
        • first-line for all patients
      • drugs
        • gentamicin
        • streptomycin
    • ciprofloxacin
      • indication
        • patients who cannot tolerate aminoglycosides
Complications
  • Renal failure
  • Meningitis
  • Erythema nodosum
 

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