What is the appropriate management for a dog bite in a patient with a penicillin (PCN) allergy?

From the Guidelines

If you have a penicillin allergy and experience a dog bite, doxycycline is typically the recommended antibiotic treatment. The standard adult dosage is 100mg taken twice daily for 5-7 days, as recommended by the Infectious Diseases Society of America 1. For children, the dose is adjusted based on weight (typically 2-4mg/kg/day divided into two doses). Alternatives for those who cannot take doxycycline include trimethoprim-sulfamethoxazole (TMP-SMX) or a fluoroquinolone like ciprofloxacin.

Key Considerations

• Dog bites require prompt treatment as they can introduce various bacteria including Pasteurella, Staphylococcus, and Streptococcus species into the wound.
• While amoxicillin-clavulanate would normally be first-line therapy due to its excellent coverage of these organisms, your penicillin allergy necessitates alternative antibiotics.
• In addition to antibiotics, proper wound care is essential - thoroughly clean the wound with soap and water, apply antiseptic, and seek medical attention for proper assessment, especially for deep wounds, facial wounds, or if signs of infection develop (increasing redness, swelling, warmth, pus, or fever).
• Tetanus prophylaxis should also be considered if your vaccination is not current.

Management Approach

• The decision to give “prophylactic” antibiotics should be based on wound severity and host immune competence 1.
• A meta-analysis of 8 randomized trials of dog bite wounds found a cumulative incidence of infection of 16%, with a relative risk of infection in patients treated with antibiotics compared with controls to be 0.56 1.
• The use of ciprofloxacin plus clindamycin or aztreonam plus vancomycin is recommended for patients with a history of an immediate-type hypersensitivity reaction to penicillin 1.

Recent Guidelines

• A 2024 systematic review for a World Health Organization guideline highlights the importance of penicillin allergy testing and delabeling for patients who are prescribed penicillin 1.
• A 2019 narrative review and consensus recommendations on the management of a surgical patient with a label of penicillin allergy emphasize the need for risk stratification and appropriate testing strategies 1.

From the FDA Drug Label

Syphilis–early: Patients who are allergic to penicillin should be treated with doxycycline 100 mg, by mouth, twice a day for 2 weeks Syphilis of more than one year’s duration: Patients who are allergic to penicillin should be treated with doxycycline 100 mg, by mouth, twice a day for 4 weeks.

The appropriate management for a dog bite in a patient with a penicillin (PCN) allergy is not directly addressed in the provided drug label. However, for patients allergic to penicillin, doxycycline is recommended for the treatment of syphilis.

• The dosage for syphilis is 100 mg, by mouth, twice a day.
• The duration of treatment depends on the stage of syphilis, but for early syphilis, it is 2 weeks and for syphilis of more than one year’s duration, it is 4 weeks 2. However, the management of a dog bite may involve treatment for other types of infections, and the provided label does not give information on the appropriate management for a dog bite.

From the Research

Management of Dog Bites

• Thorough cleansing of the wound with copious irrigation is essential in managing dog bites 3, 4.
• Assessment for the risk of tetanus and rabies virus infection, and subsequent selection of prophylactic antibiotics, are essential in the management of dog bites 5, 4.
• Initiation of prophylactic antibiotics is indicated if the dog bite has undergone primary closure; if there is a moderate or severe bite wound; for puncture wounds (especially if penetration of bone, tendon sheath, or joint), facial bites, bites to the hands or feet, or genital area bites; or wounds sustained by victims who are immunocompromised or asplenic 5.

Antibiotic Therapy for Patients with Penicillin Allergy

• For patients allergic to penicillins, suitable antibiotics for the initial empiric and expectant therapy include clindamycin and a fluoroquinolone 3.
• Amoxicillin-clavulanate is the first-line choice of antibiotic, but alternative antibiotics should be used in patients with penicillin allergy 5.

Wound Care and Prevention of Infection

• Abscesses, when present, should undergo incision and drainage 3.
• Proper preparation of the wound prior to repair will decrease infection rates 6.
• Thorough discharge instructions are an important aspect of the nursing role 6.