Human Bite

Aka: Human Bite, Clenched-fist Injury, Clenched-Fist Bite Wound, Fight Bite, Tooth-Knuckle Injury

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II. Types

  1. Occlusive Bites
    1. Teeth penetrate and sink into skin
  2. Closed Fist (Fight Bite) - most common
    1. Laceration from fist contacting teeth

III. Pathophysiology

  1. Delayed presentation is common (wound appears mild initially)

IV. Mechanism: Hand is often injured in fist fight

  1. Known as Clenched-Fist Bite Wound or Fight Bite
  2. Index or Long finger MCP joint strikes tooth (typically upper teeth)
    1. Site of injury obscured in extension
    2. High risk for infection spread
    3. Often associated with small (3-5 mm) Laceration over MCP joint
  3. Associated injuries (in 75-100% of cases) despite initial benign, superficial appearance
    1. Penetrated tendon
    2. MCP joint capsule penetration
    3. Metacarpal head
    4. Extensor Tendon Injury
    5. Patzakis (1987) Clin Orthop Relat Res (220): 237-40 +PMID:3594996 [PubMed]

V. Risk Factors

  1. Fight Bites
    1. Young males
    2. Alcohol Intoxication
  2. Human Bites
    1. Assailants with psychiatric Illness or Developmental Delay
    2. Health care workers
    3. Law enforcement

VI. Causes: Organisms

  1. Most common
    1. Mixed Anaerobes and aerobes
    2. Staphylococcus aureus
    3. Streptococcus
    4. Bacteroides
    5. Fusobacterium
    6. Eikenella corrodens (anaerobic Gram Negative Rod)
  2. Rare, but case reports
    1. HIV Infection
    2. Hepatitis B Infection

VII. Signs: Fight Bite

  1. Laceration of 3-5 mm overlying the MCP joint, and less commonly, the (PIP joint)

VIII. Exam

  1. Thorough inspection
    1. Neurovascular evaluation
    2. Extensor tendon function (Elson Extensor Tendon Test)
  2. Cleansing and debridement is critical
  3. Extend Laceration as needed for full visualize

IX. Labs

  1. Anaerobic and aerobic cultures from wound
  2. Wound Gram Stain

X. Imaging: Clenched-Fist Bite Wound

  1. Finger XRay
    1. Fracture
    2. Osteomyelitis
    3. Foreign body

XI. Management

  1. Hand surgeon Consultation (Fight Bite)
    1. Discuss with local hand surgery
    2. Protocols vary by locale and per individual consultant
    3. Some experts recommend immediate admission, debridement, irrigation and parenteral antibiotics
  2. Tetanus prophylaxis
  3. Hepatitis B Postexposure Prophylaxis
    1. Hepatitis B transmission has occurred with Human Bites (albeit rare)
    2. Prophylaxis Indicated if patient unimmunized and source cannot be tested or is suspected positive for Hepatitis B
      1. Give Hepatitis B immune globulin and Hepatitis B Vaccine
  4. Other Postexposure Prophylaxis
    1. HIV and Hepatitis C transmission are more rare than Hepatitis B transmission
    2. Transmission is possible if blood is in biter's Saliva
    3. Consider Infectious Disease Consultation regarding HIV Postexposure Prophylaxis indications
  5. Wound left open, and no structures are repaired
  6. Extensively irrigate wound
  7. Explore and debride wound under adequate lighting and exposure
    1. Extend Puncture Wounds in distal to proximal plane
    2. Remove foreign bodies
  8. Wick may be placed in wound, and removed the next day
  9. Splint hand in a position of function
  10. Apply Soft Bulky Dressing
  11. Antibiotics
    1. Precautions
      1. Obtain wound tissue for Gram Stain and culture prikor to antibiotics if possible
      2. Infections are most often polymicrobial
    2. Oral agents
      1. Amoxicillin-clavulanate (Augmentin) or
      2. Dicloxacillin with Penicillin (covers E. corrodens)
      3. Cephalexin (Keflex) with Penicillin or
      4. Clindamycin with Fluoroquinolone or
      5. Clindamycin with Trimethoprim-sulfamethoxazole
    3. Parenteral agents
      1. Indications
        1. Consider 1 parenteral dose and then oral
        2. Diabetes Mellitus
        3. Peripheral Vascular Disease
        4. Immunocompromised patient
        5. Wound older then 24 hours
        6. Signs of extensor tendon, capsule, or bone injury
        7. Systemic symptoms
        8. Concurrent Cellulitis
      2. Agents
        1. Ampicillin-sulbactam (Unasyn)
        2. Ticarcillin-clavulanate (Timentin)
        3. Cefoxitin (Mefoxin)
  12. Daily Wound Cleansing and dressing changes
    1. if satisfactory healing:
      1. Antibiotics for 2-3 weeks
    2. if not improving then:
      1. Additional surgical debridement
      2. Consider IV antibiotics
    3. Complete Extensor Tendon Laceration
      1. Requires secondary repair
      2. Otherwise Secondary wound closure is not necessary
  13. Outpatient Management Indications
    1. Indicated for wounds less than 24 hours old and no signs of infection
  14. Hospital management Indications
    1. Delayed presentation >24 hours after wound onset
    2. Immunocompromised state
    3. Systemic symptoms
    4. Joint capsule penetration

XII. References

  1. Cowling and House (2017) Crit Dec Emerg Med 31(5): 15-20
  2. Hori (2015) Crit Dec Emerg Med 29(3): 2-7
  3. Clark (2003) Am Fam Physician 68:2167-76 [PubMed]
  4. Presutti (1997) Postgrad Med 101(4): 243-54 [PubMed]

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Related Studies

Ontology: Human Bite (C0005660)

Definition (MSH) Bites inflicted by humans.
Concepts Injury or Poisoning (T037)
MSH D001734
ICD9 E928.3
ICD10 W50.3
SnomedCT 157940004, 242605002, 43028005
English Bite, Human, Bites, Human, Human Bites, human bites (diagnosis), human bites, Human bite - accidental, Bites, Human [Disease/Finding], Bite;human, bite human, biting humans, bites human, bites humans, Human bite (disorder), Human bite, Human bite (morphologic abnormality), bite; human, human; bite, Human Bite, human bite, Human bite (finding), Human bite (event)
Spanish mordedura de humano (evento), mordedura de humano (hallazgo), mordedura de humano, mordedura humana (anomalía morfológica), mordedura humana, Mordedura humana, Mordeduras Humanas
Italian Morso umano, Morsi umani
Japanese 人による咬傷, ﾋﾄﾆﾖﾙｺｳｼｮｳ
Swedish Människobett
Czech kousnutí člověkem, Kousnutí člověkem
Finnish Ihmisen puremat
Russian UKUSY CHELOVECHESKIE, УКУСЫ ЧЕЛОВЕЧЕСКИЕ
Polish Ukąszenie przez człowieka, Ugryzienie przez człowieka
Hungarian Emberi harapás
Norwegian Menneskebitt
Dutch beet; humaan, humaan; beet, mensenbeet, Beet, mensen-, Beten, mensen-, Mensenbeet, Mensenbeten
Portuguese Mordedura humana, Mordeduras Humanas
French Morsure humaine, Morsures humaines
German Menschenbiss, Bisse, menschliche, Menschenbisse
Derived from the NIH UMLS (Unified Medical Language System)

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