Review Topic
  • 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.
  • 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
  • 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
  • Chest radiography
    • indication
      • suspected lung involvement
    • findings
      • diffuse patchy infiltrates or consolidations
  • 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
  • Anthrax
    • distinguishing factor
      • presents with a necrotic ulcer rather than buboes
  • 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
  • Acute respiratory distress syndrome
  • Disseminated intravascular coagulopathy
  • Septic shock
  • Lymphatic scarring and chronic lymphedema
  • Superinfection of buboes with other bacteria

Please rate topic.

Average 5.0 of 2 Ratings

Questions (2)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Private Note