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Snapshot
  • A 53-year-old man presents to occupational health for suspected exposure to the plague. He works in a research laboratory that conducts research on infectious diseases and accidentally poked himself with a needle he used on an infected animal. He has had headaches, fatigue, and enlarged and painful "bug bite-like lesion" on his right groin.  On physical exam, he has inguinal lymphadenopathy and a large and tender buboe in the right inguinal area. He is started on the appropriate antibiotics, and the incident is reported to the Centers for Disease Control and Prevention.
Introduction
  • Classification
    • Yersinia pestis 
      • a nonmotile, gram-negative, facultative intracellular bacillus
        • non-lactose fermenting, oxidase negative, and does not produce H2S
      • reservoirs are rats and prairie dogs
      • transmitted via fleas 
      • causes the bubonic plague (most common) and pneumonic plague
  • Epidemiology
    • incidence
      • rare but outbreaks occur in the Southwest in the US
    • demographics
      • occurs in young people
    • risk factors
      • exposure with infected patients or small rodents, alive or dead
      • flea bites
      • occupational exposure
  • Pathogenesis
    • produces endotoxin, coagulase, and fibrinolysin
    • bacteria migrate to regional lymph nodes and survive intracellularly within macrophages
      • F1 capsular antigen is antiphagocytic
  • Prevention
    • plague vaccine
      • field workers in endemic areas
      • laboratory personnel who work with Yersinia pestis
  • Prognosis
    • if untreated, the disease will lead to death
    • if untreated, mortality rates range from 10-50%
    • pneumonic plague has the highest mortality
Presentation
  • Symptoms
    • sudden onset high fever and chills
    • headache
    • myalgias
    • fatigue
  • Physical exam
    • bubonic plague  
      • unilateral swollen and tender lymph nodes (buboes)
      • often in the groin (Greek bubon = groin) and axilla
      • can grow up to 10 cm in size
      • may have eschar and vesicles
      • buboes may rupture and have malodorous pus discharge
    • pneumonic plague
      • cough
      • chest pain
      • hemoptysis
      • dyspnea
Imaging
  • Chest radiography
    • indication
      • suspected lung involvement
    • findings
      • diffuse patchy infiltrates or consolidations
Studies
  • Peripheral blood smear
    • toxic granulations and Dohle bodies
    • Wright-Giemsa stain with rods
    • Wayson stain reveals “safety pin” appearance of bacteria with bipolar staining
  • Labs
    • positive blood cultures are diagnostic but can be hazardous
    • rapid F1 antigen detection via immunofluorescence
  • Lymph node aspirate
    • Yersinia pestis on microscopy or culture
  • Making the diagnosis
    • based on clinical presentation and laboratory studies
Differential
  • Anthrax
    • distinguishing factor
      • presents with a necrotic ulcer rather than buboes
Treatment
  • Management approach
    • mainstay of treatment is supportive care and antibiotics
  • Conservative
    • supportive care
      • indication
        • all patients
      • modalities
        • aggressive hydration
        • respiratory support
        • hemodynamic support
  • Medical
    • aminoglycosides
      • indication
        • all patients
    • doxycycline
      • indication
        • treatment
    • fluoroquinolones
      • indication
        • treatment
        • post-exposure prophylaxis
  • Operative
    • incision and drainage
      • indication
        • enlarging buboes
Complications
  • Acute respiratory distress syndrome
  • Disseminated intravascular coagulopathy
  • Septic shock
  • Lymphatic scarring and chronic lymphedema
  • Superinfection of buboes with other bacteria

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