Snapshot A 24-year-old male self-presents to the ED. He reports having argued with and being bit by his girlfriend about 4 hours ago (See image). The skin does not appear erythematous or infected. No subcutaneous crackles are appreciated. Strength and neurovascular status distal to the bite are preserved. No other lesions are observed throughout his body. The patient reports a complete immunization history. The bite is cleaned with mild soap and irrigated with sterile water. Forearm radiographs are unremarkable for residual tooth fragments. No sutures are applied. After evaluation by the on-call plastic surgery resident, the patient is discharged with Tdap vaccination and started on a 7-day course of amoxicillin/clavulanic acid with follow-up at the hospital plastic surgery clinic in 1 week. Introduction 1% of all visits to the emergency department 60-90% of mammalian bites are by dogs however, 80% of cat bites vs. 5% of dog bites become infected human bites also have high likelihood of becoming infected Presentation Mammalian bites extremities are most common site of presentation of dog bites cat scratches or bites may present with cat-scratch disease (bartonella henselae) papule at site of scratch followed by fever, tender LAD, and malaise most common organism of infection is Pasteurella multocida Human bites most commonly over dorsum of metacarpophalangeal joint from punch into mouth mouth organisms can get trapped in joint space when fit unclenches and overlying skin forms air-tight covering ideal for anaerobic growth can lead to septic arthritis most common organisms: S. aureus > α hemolytic Strep > Eikenella > Bacteroides Evaluation History time and circumstance of bite (AMPLE history) tetanus immunization status rabies risk comorbid conditions (particularly immunocompromising diseases) HIV/hepatitis risk (human bites) Physical exam type of wound (abrasion, laceration, puncture, crush) degree of direct tissue damage (skin, bone, tendon, neurovascular status) Investigations radiographs to rule out foreign body, fracture, subcutaneous air culture for aerobic, anaerobic organisms Management Best initial step: aggressive irrigation with debridement Closure bites are usually left open to heal by secondary intention only consider primary closure for bite wounds on face otherwise contraindicated Urgent surgical exploration of joint with drainage/debridement of infected tissue splint to prevent joint space from being covered by skin Prophylactic antibiotics amoxicillin-clavulanic acid if penicillin allergy, use clindamycin plus doxycycline or clindamycin plus TMP-SMX Tetanus prophylaxis Rabies post-exposure prophylaxis both vaccine and immunoglobulin administer vaccine via intramuscular route infiltrate wound with immunoglobulin administer remainder via IM route human bites: NEVER required dog, cat, ferret bites if healthy or no signs of rabies after 10 days observation: no prophylaxis if bite exposure is around head or neck: prophylaxis if rabid or observation not possible: prophylaxis all other animals (raccoons, bats, coyotes, etc.): prophylaxis HIV/hepatitis prophylaxis consider if source of bite is from diseased host