Updated: 3/29/2019

Pasteurella multocida

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  • A 40-year-old woman presents to the emergency room after being bitten by a cat. She had been visiting her boyfriend, who has 5 cats, when one of them was wary of strangers and bit her on the thumb. She cleaned it with some water and soap. On physical exam, she has a normal range of motion and sensation in her thumb. Her pulses are 2+ bilaterally. The wound is irrigated with sterile saline and wound is examined for any foreign bodies. She is started on empiric antibiotics to cover bacteria associated with cat bites.
  • Classification
    • Pasteurella multocida
      • an facultative anaerobic gram-negative coccobacillus
      • encapsulated
      • can cause cellulitis at the site of inoculation
      • can also cause osteomyelitis
  • Epidemiology
    • incidence
      • high in cat bites
    • demographics
      • male > female
      • more common in those < 20 years of age
    • risk factors
      • cat bites > dog bites
      • bites in the hand
      • deep penetrating wounds
      • immunosuppression
  • Pathogenesis
    • direct inoculation of oral pathogens from animal bites into the wound, leading to infection
    • cats have narrow and sharp teeth, which can inflict deep penetrating wounds with tiny wound openings that prevent good drainage
  • Symptoms
    • fevers
    • chills
  • Physical exam
    • wound with signs of cellulitis
      • purulence
      • surrounding erythema
      • edema
    • osteomyelitis
      • deep penetrating wound with bone involvement
    • may have a foreign body in the wound
  • Radiography
    • indication
      • to rule out fracture
    • findings
      • fracture of bone
      • early signs of osteomyelitis
        • soft tissue swelling
        • focal bony lysis or cortical loss
        • blurring of normal fat planes
  • Labs
    • wound culture
    • blood cultures if a systemic infection is suspected
    • catalase positive
    • oxidase positive
    • grows on 5% sheep's blood
  • Making the diagnosis
    • based on clinical presentation
  • Tularemia
    • distinguishing factors
      • associated with rabbits and ticks not with an animal bite
      • presents with skin ulcer and lymphadenopathy
  • Management approach
    • wounds are not typically closed due to the risk of infection
  • Conservative
    • wound care
      • indication
        • all patients
      • modalities
        • sterile saline irrigation
        • removal of any foreign bodies
  • Medical
    • amoxicillin/clavulanate
      • indication
        • all patients
    • post-exposure prophylaxis
      • indication
        • patients with exposure risk
      • prophylaxis for
        • tetanus
        • rabies
  • Abscess
    • more common with cat bites

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