Thursday, April 17, 2025

👊Human Bite (“Fight Bite”) to the Hand


Scenario
A 28‑year‑old man presents to the ED 12 hours after punching another person in the face and sustaining a 1 cm laceration over the dorsal aspect of his right third metacarpophalangeal joint. He cleaned it at home but now has:

  • Increasing pain, swelling, and erythema over the joint

  • Temperature 38.2 °C, pulse 100 bpm

  • Mild crepitus when extending the finger

  • No obvious abscess, but the wound is tender with a small serosanguineous discharge

He is otherwise healthy, with no penicillin allergy.


Question

Which empiric oral antibiotic regimen is most appropriate for this patient?

A) Amoxicillin–clavulanate
B) Clindamycin monotherapy
C) Doxycycline + metronidazole
D) Cephalexin
E) Dicloxacillin

 Correct Answer: A) Amoxicillin–Clavulanate


📘 Mini‑Lesson & Teaching Points

            Likely Pathogens:

    • Eikenella corrodens (Gram‑negative), oral anaerobes

    • Staphylococcus aureus, Streptococcus spp.

    • Note: Pasteurella multocida (from cat bites) can mimic Eikenella corrodens in terms of rapid onset cellulitis and similar antibiotic susceptibilities, but human‐bite wounds classically involve Eikenella.


  1. Why Amoxicillin–Clavulanate?

    • Single‑agent cover for Eikenella and anaerobes, plus Staph/Strep

    • Excellent oral bioavailability; standard first‑line for human‐bite wounds

  2. Why the Others Are Less Suitable

    • B) Clindamycin: No reliable Gram‑negative/Eikenella coverage

    • C) Doxycycline + Metronidazole: Covers Eikenella and anaerobes—acceptable second‐line if β‑lactam allergy, but two drugs vs one

    • D) Cephalexin: Good for MSSA/Strep only; misses Gram‑negatives/anaerobes

    • E) Dicloxacillin: Narrow anti‑staph agent; no Gram‑negative or anaerobic activity

  3. Alternative for Penicillin Allergy

    • Doxycycline + metronidazole or moxifloxacin monotherapy are guideline‑endorsed alternatives in true β‑lactam allergy 

  4. Additional Management

    • I&D or joint washout if septic arthritis is suspected (crepitus, painful ROM)

    • Tetanus prophylaxis and update immunisation if needed

    • Leave the wound open—do not suture human‐bite wounds due to high infection risk


Key Take‑Home:
For uncomplicated human‐bite cellulitis in a non‐allergic patient, amoxicillin–clavulanate is the empiric oral antibiotic of choice. In those with penicillin allergy, switch to doxycycline + metronidazole or moxifloxacin.

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