Bite Wounds

Jonathan Pirie

Introduction

Human and animal bite wounds are common: ˜1% of all emergency department (ED) visits
Most bite wounds are minor, but may cause significant morbidity
Management requires an understanding of the microbiology of wound infections, assessment of low- versus high-risk wounds, treatment strategies, and tetanus and rabies prophylaxis
Notify local public health department for all animal bite wounds

Frequency and Infection Rates

Dog bites are most common type of animal bite but have low infection rates
Younger children are most susceptible to significant morbidity and occasional mortality
Cat bites less frequent but have much higher infection rate
- Cats tend to inflict deep puncture wounds; they are hard to clean and tend to occur on hands and upper extremities
Human bites are least common yet have a relatively high infection rate
Beware of closed-fist injuries affecting area around the metacarpal-phalangeal joints

Microbiology

Bite wounds often involve multiple species:
- Pasteurella species: dog and cat bite wounds
- Eikenella corrodens: human bites
- Capnocytophaga canimorsus: dog or cat bites, can cause septicemia and shock in patients with asplenia or immunosuppression
- Other common organisms: streptococci, staphylococci, oral anaerobes
Amoxicillin/clavulanic acid is antimicrobial of choice: covers all potential pathogens in bite wound infections

Table 61.1 Bites and Infection Rates by Species

Bite Wound Management

Copious irrigation: normal saline with a 20-mL or larger syringe and 19G angiocath
Cautious debridement if indicated
Prophylactic antibiotics (high risk: see below)
Therapeutic antibiotics if signs of infection
Primary closure: low-risk lacerations
Immobilization in position of function
Elevation
Tetanus toxoid if indicated +/− tetanus immune globulin as necessary
Rabies prophylaxis if indicated

Note: Antibiotics alone not sufficient

Prophylactic Antibiotics

Controversial; limited studies
If present to ED within 24 hours, without signs of infection, and have high-risk criteria, consider for antibiotic prophylaxis
Give first dose in emergency department
Duration 3-5 days
Antibiotic of choice: amoxicillin-clavulanic acid
Alternatives: penicillin V + (cephalexin or cloxacillin)
Penicillin allergic: clindamycin + TMP-SMX