Topics / Surgery / Wounds / Bite Wounds

Summary This is a brief article is a summary of an approach to a human bite wound. We follow a 5 step approach while always keeping in mind the complications and dangers of a "simple" bite wound!

Basics

Human bite wounds are very dangerous. This is important to keep in mind because sometimes they may look harmless! They are associated with a few complications, such as infections, puncture wounds, and transmission of other diseases such as HIV, hepatitis (B, C), herpes simplex, syphilis, tetanus, and others. Local wound infection is prevalent since human bite wounds inculcate aerobic and anaerobic microorganisms from the mouth into the bite wound. The most common and dangerous area to be bitten is on the hand.

Classification

Clenched-fist injuries
- “The attacker gets an injury”
- A person with closed first strikes another person’s teeth. In this process, this action creates a small wound on the attacker’s hand. This wound usually occurs on dorsal surface of the metacarpophalangeal joints or the proximal interphalangeal joints. This wound is commonly associated with joint penetration, fractures or laceration of the extensor tendons. This is a very dangerous human bite and needs aggressive management.
Occlusive bites
- “The attacker causes an injury”
- This occurs when the attacker bites a body part and causes a break in the skin. Several types of wound injuries can occur such as avulsions, lacerations and other crushing injuries.

Transmission of Infections The wound is inoculated with both anaerobes and aerobes. Commonly cultured microorganism include: Staphylococcus, Streptococcus, Corynebacterium, Eikenella, E. corrodens, Bacteroides, Fusobacteria, Prevotella and Peptostreptococcus.

Others: Hepatitis B and HIV are present in saliva. Hepatitis B being around 100 times more infectious than HIV. HIV is less likely to be transmitted because it is present in lower levels than in the blood and there are other inhibitory factors present in the saliva that makes the virus non-infective. For this reason, patients with human bite wounds should be given hepatitis B prophylaxis and in severe wounds, post-exposure prophylaxis for HIV should be considered as well if the source is HIV positive.

Management

This includes the following:

Wound Management
Tetanus Prophylaxis
Antibiotics
Hepatitis B Prophylaxis
HIV Prophylaxis

Step 1: Clean the wound

The wound needs to be washed well with soap under running water for around 5 – 10 minutes. We should use Chlorhexidine 0.05% aqueous solution and we should also apply a disinfectant such as Povidone iodine 10% solution if available. After cleaning the wound, dress the wound (not with compressive dressing). Avoid suturing bite wounds unless it is on the head or face. If the wound needs closure then try to review the patient after 48 hours in order to perform secondary closure.

Step 2: Tetanus prophylaxis

If the patient has not been previously immunized within the last 5 years: Give the patient Tetanus toxoid (TT) 0.5ml IM stat.

Step 3: Antibiotics

The EML guidelines provides antibiotics for patients that do not need admission. If the patient meets the referral criteria, you should consider the patient or referring the patient. These patients will benefit from IV antibiotics.

Amoxicillin/clavulanic acid (875/125), 1g PO 12 hourly for 5 days AND
1. If there is a penicillin allergy, substitute Amoxicillin/clavulanic acid for Azithromycin 500mg PO OD for 3 days
Metronidazole, 400mg PO 8 hourly for 5 days.

Step 4: Hepatitis B prophylaxis

This should be done if the patient has a bite that is severe enough to cause bleeding. Hepatitis B Immune Globulin (HBIG) should preferably be given within 24-72 hours after exposure (or within 7 days). If it is going to take >24 hours to obtain HBsAb results, then just treat the patient as group C. If the patient is vaccinated and is a health care worker, repeat the HBsAb after 1-2 months to see if there is adequate immune response (titre > 10 units/ml).

Vaccination status and antibody response of exposed person	Source of the patient
Vaccination status and antibody response of exposed person	HBsAg Positive	HBsAG Negative	HBsAg unknown
Group A:Exposed person unvaccinated or vaccination is incomplete	-HBIG 500 units IM AND Hep B vaccine IM monthly for 3 months (3 doses)	-Hepatitis B vaccination at month 0, month 1 and month 6	-HBIG 500 units IM AND Hep B vaccine IM monthly for 3 months (3 doses)
Group B: Exposed person vaccinated AND known to have HBsAb titre ≥ 10 units/ml	No treatment	No treatment	No treatment
Group C: Exposed person vaccinated AND HBsAb titre < 10 units/ml OR level is unknown	-HBIG 500 units IM AND Hep B vaccine IM monthly for 3 months (3 doses)	No treatment	-HBIG 500 units IM AND Hep B vaccine IM monthly for 3 months (3 doses)

Step 5: Prophylaxis

The EML guidelines states that the risk of HIV transmission through biting is “negligible”. They state that post-exposure prophylaxis is not indicated after a human bite. However, some health care professionals provide their patients with HIV prophylaxis either way, especially if the wound is severe. Read HIV Post-Exposure Prophylaxis in order to learn more.

When to refer the patient:

Deep or large wounds that may require suturing
Extensive bleeding
Shock
Infected wounds that may require Orthopedic intervention
Hand bites

Complications

Cosmetic deformity
Disability (amputation of fingers)
Infectious tenosynovitis
Septic arthritis
Abscess
Amputations
Transmission of infections (Hepatitis B, HIV)
Osteomyelitis
Necrotizing fasciitis

Further Reading 1. The National Department of Health, South Africa: Essential Drugs Programme. Primary Healthcare Standard Treatment Guideline and Essential Medicine List. 7th ed. South African National Department of Health; 2020.
2. Emedicine.medscape.com. 2022. Human Bites Guidelines: Guidelines Summary. [online] Available at: [Accessed 20 September 2022].

Published on September 20, 2022

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Human Bites