Skin & Soft Tissue: Bite Wounds

Human Bite Wounds

Microbial Infection

  • High Risk of Infection
    • Superficial Wounds: 2%
    • Occlusion Bites: 10%
    • Clenched-Fist Injuries (Traumatic Puch): > 25%
  • Most Common Organisms:
    • Skin Flora (Staphylococcus & Streptococcus)
    • Oral Flora (Eikenella corrodens, Prevotella, Fusobacterium & Porphyromonas)

Treatment

  • Uninfected: Irrigation & Wound Care
    • Generally Wounds Should Be Left Open to Heal by Secondary Intention & Not Be Closed Primarily
    • Indications for Antibiotic Prophylaxis:
      • Wounds Closed Primarily
      • Wounds to Face, Hands or Genitals
      • Close Proximity to Bones or Joints
      • Diabetic or Immunocompromised
      • Deep Wounds
      • Association with Crush Injury
    • Consider Tetanus, Hepatitis & HIV Prophylaxis 
  • Infected: Wound Care & Antibiotics
    • May Require IV Antibiotics if Severely Ill or Rapidly Progressing
    • Surgical Debridement May Be Required

Antibiotic Regimen (If Indicated)

  • First-Line: Amoxicillin/Clavulanate (Augmentin)
  • Second-Line (Penicillin Allergy): Should Cover Eikenella & Anaerobes
    • Eikenella Coverage:
      • Trimethoprim-Sulfamethoxazole (TMP-SMX/Bactrim)
      • Doxycycline
      • Ciprofloxacin
    • Anaerobic Coverage:
      • Metronidazole (Flagyl)
      • Clindamycin

Human Teeth 1

Common Animal Bite Wounds

Microbial Infection

  • Generally Polymicrobial
  • Most Common Organisms: Streptococci (#1) & Staphylococci (#2)
  • Other Organisms:
    • Pasteurella multocida
    • Bartonella henselae – From Cats
    • Capnocytophaga
    • Anaerobes

Dog Bites

  • Most Common Animal Bite (90%)
  • Most Common in Children
  • Tend to Be Large & Open
  • Less Likely to Become Infected

Cat Bites

  • Most Common in Adult Women
  • Deeper Penetration
  • More Likely to Become Infected

Treatment

  • Uninfected: Irrigation & Wound Care
  • Infected: Irrigation, Wound Care & Antibiotics
    • May Require IV Antibiotics if Severely Ill or Rapidly Progressing
    • Surgical Debridement May Be Required

Antibiotic Regimen (If Indicated)

  • First-Line: Amoxicillin/Clavulanate (Augmentin)
  • Second-Line (Penicillin Allergy): Should Cover Pasteurella & Anaerobes
    • Pasteurella Coverage:
      • Trimethoprim-Sulfamethoxazole (TMP-SMX/Bactrim)
      • Doxycycline
      • Ciprofloxacin
    • Anaerobic Coverage:
      • Metronidazole (Flagyl)
      • Clindamycin

Dog Teeth 2

Cat Teeth 3

Spider Bite Wounds

Black Widow (Latrodectus)

  • Appearance: Shiny Black a Red Structure on Body
  • Habitat:
    • All Throughout the US
    • Rarely Found Indoors
    • Most Commonly Found Around Homes (Garages & Sheds)
  • Effects:
    • Indistinct Local Lesions
    • Systemic Effects are Uncommon
      • Muscle Pain
      • Localized Diaphoresis Around the Bite
      • Muscle Rigidity
      • Tetany & Seizures

Brown Recluse (Loxosceles)

  • Appearance: Brown without Significant Distinguishing Features
  • Habitat:
    • Mostly in the Mid-West & South US
    • Most Common Inside Homes
  • Effects:
    • Red Plaque with Central Pallor
    • May Progress to Necrosis
    • Systemic Effects are Rare

Treatment

  • Primary Treatment: Local Wound Care & Pain Management
    • Consider Tetanus Prophylaxis
  • Debride Necrotic Tissue Once Fully Demarcated (Avoid Early Debridement)
  • Antivenom:
    • Consider for Black Widow Spiders with Moderate-Severe Envenomation Unresponsive to Supportive Cares
    • None Exist for Brown Recluse Spiders

Black Widow 4

Brown Recluse 5

Snake Bite Wounds

Systemic Effects

  • Tissue Necrosis
  • Neurotoxicity (Ptosis, Drooling, Flaccid Paralysis or Gait Disturbance)
  • Coagulopathy
  • Rhabdomyolysis
  • Shock
  • *Effects Vary by the Snake & Venom

Treatment

  • Keep Patient Calm & Still
    • Immobilize/Splint the Extremity as Well
  • May Consider Pressure Bandage Immobilization (PBI)
    • Venom Spread & Deterioration May Occur After PBI Removal
    • PBI Should Not Be Removed Until the Patient Has Received Antivenom or they Have Been Fully Evaluated with No Evidence of Envenomation
  • Keep Extremity Below the Level of the Heart – Slow Lymphatic Venom Absorption
  • Consider Antivenom Administration if Indicated
  • Local Wound Care
  • Consider Tetanus Prophylaxis

Antivenom

  • Types:
    • Monovalent – Developed Against a Single Species
    • Polyvalent – Developed Against Multiple Different Species Sharing a Geographical Region
  • Indications:
    • Rhabdomyolysis
    • Severe Systemic Illness
    • Severe or Rapidly Progressing Local Effects

Avoid Unproven Methods

  • Orally “Sucking Out” the Venom
  • Mechanical Suction Devices
  • Incision to Bleed
  • Tourniquets

References

  1. Gunnarsson T. Wikimedia Commons. (License: CC BY-SA-4.0)
  2. Yaali. Wikimedia Commons. (License: CC BY-SA-4.0)
  3. Gonzalez G. Wikimedia Commons. (License: CC BY-2.0)
  4. Chepyle. Wikimedia Commons. (License: CC BY-SA-3.0)
  5. Br Recluse Guy. Wikimedia Commons. (License: Public Domain)