A 7-year-old girl is brought to the emergency department due to a cat bite on her right arm. She was bitten while picking up a neighbor's cat by its tail. Afterward, her mother immediately cleaned the wound with hydrogen peroxide. The patient's vaccinations are up to date, and her most recent tetanus vaccine was 3 years ago. Her temperature is 36.9 C (98.4 F), blood pressure is 108/70 mm Hg, pulse is 107/min, and respirations are 21/min. Physical examination shows a deep puncture wound on the anterolateral aspect of the patient's right forearm. There is no visible debris in the wound and no active bleeding. Neurovascular function is intact. Her wound is copiously irrigated with saline and cleaned with povidone-iodine. Which of the following is the best next step in management?
Management of mammalian bites | |
Wound care |
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Imaging |
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Infection management |
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*Primary closure may be considered for cosmetic reasons (eg, facial laceration) or involvement of deep musculoskeletal or vascular structures. | |
This patient has a puncture wound from a cat bite. Cats have long, sharp teeth that can inoculate oral flora deep into skin, reaching soft-tissue structures (eg, nerves, tendon sheaths). Therefore, cat bites are much more likely to cause serious infection (eg, septic arthritis, osteomyelitis) than dog bites and always warrant antibiotic prophylaxis.
Bite wound infections are usually polymicrobial and caused by human skin flora (eg, streptococci, Staphylococcus aureus) and/or animal oral flora. Oral flora of cats includes Pasteurella multocida (gram-negative coccobacilli) and anaerobes. The agent of choice for infection prophylaxis is amoxicillin-clavulanate; amoxicillin has activity against gram-positive organisms and P multocida while clavulanate provides coverage against beta-lactamase–producing anaerobes.
Acute management of cat bites also includes copious irrigation, and the wound is typically left open to heal by secondary intention. Unless there is concern for cosmetic appearance (eg, facial wound), primary wound closure with sutures is generally avoided due to higher risk for infection (Choice B).
(Choice A) A tetanus toxoid–containing booster should be administered to those who sustain a bite and are either incompletely vaccinated for age or last received a dose of the vaccine ≥5 years ago. This patient is up to date with vaccinations and received a tetanus vaccine 3 years ago; therefore, she does not require a booster dose.
(Choice C) Observation and close follow-up alone are appropriate for immunocompetent individuals with minor dog bites that are located on low-risk areas (eg, trunk). Because cat bites are typically deep puncture wounds, the risk of infection is high, and all cat bites warrant antibiotic prophylaxis.
(Choice E) Azithromycin has activity against Bartonella henselae, the causative pathogen of cat-scratch disease. However, antibiotic prophylaxis against this condition is not recommended in immunocompetent individuals, and azithromycin is not recommended as prophylaxis against wound infection in mammalian bites.
(Choice F) Clindamycin covers gram-positive skin flora (eg, Staphylococcus, Streptococcus) and most oral anaerobes. Although clindamycin is commonly used to treat cellulitis and abscesses unrelated to bites, it has no activity against P multocida and therefore should not be used as monotherapy for prophylaxis following a cat bite.
Educational objective:
Cat bites wounds are at high risk for infection due to inoculation of bacteria into deep puncture wounds. All cat bites warrant antibiotic prophylaxis, and first-line therapy is amoxicillin-clavulanate, which has activity against skin flora and cat oral flora (eg, Pasteurella multocida, anaerobes).