Bite wounds

Use the table below for the antimicrobial treatment overview of animal bites.

• FigureAnimal bites - treatment overview

Discuss treatment of pig bites with a microbiologist.

Prophylactic antibiotics are indicated if the wound has been caused by a cat or pig, or if it is a high risk injury, such as:

• animal bites to the hand, foot, and face and genitalia
• puncture or crush wounds; wounds requiring surgical debridement
• wounds involving bones, joints, tendons, ligaments, or suspected fractures
• bites on limbs with impaired circulation
• wounds that have undergone primary closure
• people who are at risk of serious wound infection (for example, those who are diabetic, cirrhotic, asplenic, immunocompromised, or at extremes of age)
• people with a prosthetic valve or joint
• delayed presentation (more than 8 hours but less than 24-48 hours)

Take a pus sample or deep wound swab for culture before cleaning the wound and starting antibiotics. State clearly on the form that the swab is from an infected animal bite.

Assess the risk of tetanus and rabies. For infected wounds, review at 24 and 48 hours to ensure that infection is responding to treatment, particularly if the patient has been prescribed a non-penicillin based regimen.   

If the bite wound is not infected, advise the person to check for signs of infection and if these develop to attend urgently for review.

Primary care: Refer patients with wounds that require surgical debridement or wound closure, wounds on the hand or foot, and wounds that involve joints, tendons, or ligaments. Refer all patients with severe infection and signs of systemic illness. 

First line:

Doxycycline oral 100mg 12 hourly

N.B. In pregnant patients, doxycycline is contraindicated.

Second line:

Amoxicillin oral 1g 8 hourly

Lyme disease is unlikely if a tick has been attached for less than 24 hours. Erythema migrans (EM) develops within six weeks of a tick bite.

Investigation and treatment of late manifestations of Lyme disease, such as Lyme arthritis, Lyme carditis or neuroborelliosis should be discussed with an infection specialist.

Any patient with EM following significant exposure or known tick bites should be treated for Lyme disease without confirmatory testing. In the absence of documented tick bites and/or clinical features of Lyme disease, neither treatment nor serological testing are indicated.

First line:

Co-amoxiclav oral 375mg 8 hourly (increased to 625mg 8 hourly in severe infections)

If true penicillin / beta-lactam allergy:

Clarithromycin oral 250-500mg 12 hourly

and

Metronidazole oral 400mg 8 hourly

N.B. Clarithromycin should not be prescribed concurrently with ciclosporin, sirolimus or tacrolimus.

Prophylactic antibiotics are advised for all human bites. Assess the risk of blood borne virus transmission.   

Take a pus sample or deep wound swab for culture before cleaning the wound and starting antibiotics. State clearly on the form that the swab is from an infected human bite.

For infected wounds, review at 24 and 48 hours to ensure that the infection is responding to treatment, particularly if the patient has been prescribed a non-penicillin based regimen. Advise the patient to attend urgently for review if the infection worsens or if they feel increasingly unwell. 

Primary care: Refer patients with wounds that require surgical debridement or wound closure, wounds on the hand or foot, and wounds that involve joints, tendons, or ligaments. Refer all patients with severe infection and signs of systemic illness.