Human bites

Assessment

Carefully examine bite wounds and clenched-fist injuries to identify deeper injuries, devitalised tissue and retained foreign bodies.

Skin breaks over the knuckles can lead to the introduction of both skin and oral flora into fascial layers of the hand, with potential spread to nearby joint and soft tissues.

Review the tetanus immunisation status of patients. Consider tetanus prophylaxis.

For human bite injuries with associated blood exposure, consider the need for post exposure prophylaxis against bloodborne viruses (e.g. hepatitis B or HIV).

Management

Investigations

Before starting antibiotic therapy, collect infected tissue for gram stain and aerobic and anaerobic culture. Specify that the sample is from a bite or clenched-fist wound on the laboratory request.

Image as required to rule out fractures and foreign bodies.

Treatment

The recommended management of bites and clenched-fist injuries is thorough cleaning, irrigation, debridement, elevation and immobilisation.

Wound closure

For most patients with human bite wounds, leave the wounds open to heal by secondary intention rather than by primary closure, given the high risk of subsequent infection.

Indications for surgical consultation

Most human bites can be managed at the bedside. Surgical consultation is warranted for:

• clenched-fist wounds with associated fracture, joint disruption, retained foreign body or abnormal extensor tendon examination
• complex facial lacerations
• wounds on the hand or feet
• deep wounds, especially if significant avulsion or amputation is present
• wounds associated with neurovascular compromise.

Antibiotic therapy

Antibiotic therapy is required for infected bites and clenched-fist injuries.

Antibiotic therapy is required for infected bite injuries refer to Therapeutic Guidelines: Bite wound infections including clenched-fist injury infections (NSW Health login required).

For bites and clenched-fist injuries that are not infected, antibiotic therapy is usually not necessary for otherwise healthy individuals if the risk of wound infection is low.

Give presumptive therapy if the risk of wound infection is high, including if any of these conditions are true:

• presentation to medical care is delayed by eight hours or more
• the wound is a puncture wound that cannot be debrided adequately
• the wound is on the hands, feet or face
• the wound involves deeper tissues (e.g. bones, joints, tendons)
• the wound involves an open fracture
• the patient is immunocompromised (e.g. due to asplenia or immunosuppressive medications) or has alcoholic liver disease or diabetes.

Background

Bites, including clenched-fist injuries, often become infected.

Types of bites that cause serious injury or infection:

• Occlusal bites – Frank bites by human teeth. On examination, they appear as semicircular or oval areas of erythema or bruising. The skin may or may not be intact.
• Clenched-fist injuries – Also known as fight bites, are lacerations from a clenched fist of one person striking the teeth of another. The lacerations are small (usually ≤15mm) and are typically over the third and fourth metacarpophalangeal or proximal interphalangeal joints of the dominant hand.

The bacteria associated with human bites (including clenched-fist injuries) are Staphylococcus aureus, Eikenella corrodens, Streptococcus species and beta-lactamase–producing anaerobic bacteria.

Patient information

Facial injuries
Source: Healthdirect