From the Guidelines
For a cat bite in someone with a penicillin allergy, the most effective antibiotic regimen is Doxycycline (100 mg twice daily for 5-7 days) or a combination of a fluoroquinolone, such as Ciprofloxacin (500 mg twice daily) or Levofloxacin (750 mg daily), with Metronidazole (250-500 mg three times daily). This recommendation is based on the most recent and highest quality study available, which prioritizes the treatment of skin and soft tissue infections, including those caused by cat bites 1.
Key Considerations
- Cat bites can introduce a variety of bacteria, including Pasteurella multocida, which can cause rapid infection and has a high prevalence in cat bites 1.
- The chosen antibiotic regimen should cover both aerobic and anaerobic bacteria commonly found in cat bites.
- Doxycycline is a good option as it has excellent activity against Pasteurella multocida, as well as some streptococci, although some streptococci are resistant 1.
- Fluoroquinolones, such as Ciprofloxacin or Levofloxacin, can be used in combination with Metronidazole to provide broad coverage against both aerobic and anaerobic bacteria, but it's essential to note that they may not cover MRSA 1.
Additional Recommendations
- Thoroughly clean the wound with soap and water and apply antiseptic to reduce the risk of infection.
- Seek medical attention, especially for deep puncture wounds, hand injuries, or if signs of infection develop (increasing redness, swelling, warmth, or pus).
- Tetanus prophylaxis should be considered if the vaccination is not current.
- It's crucial to choose an antibiotic regimen based on the most recent guidelines and the specific patient's needs, taking into account any allergies or resistance patterns 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 recommended antibiotic treatment for a patient with a cat bite who is allergic to penicillin is doxycycline. The dosage is 100 mg, by mouth, twice a day. However, the exact duration of treatment is not specified in the label for cat bites.
- The dosage of doxycycline for syphilis (which can be used as a reference for other infections) is 100 mg, by mouth, twice a day for 2 weeks for early syphilis and 4 weeks for syphilis of more than one year’s duration 2.
From the Research
Antibiotic Treatment for Cat Bites
- The majority of cat bite wounds become infected, with Pasteurella multocida being the most commonly cultured bacterium 3.
- Phenoxymethyl penicillin is recommended as the drug of choice for treating infections associated with cat and dog bites 4.
- However, in cases where the patient is allergic to penicillin, alternative antibiotics such as ciprofloxacin may be recommended 4.
Penicillin Allergy Considerations
- Approximately 10% of the US population reports an allergy to penicillin, but clinically significant IgE-mediated or T lymphocyte-mediated penicillin hypersensitivity is uncommon (<5%) 5.
- Patients with a low-risk history of penicillin allergy can undergo direct amoxicillin challenge, while those with a moderate-risk history can be evaluated with penicillin skin testing 5.
- The goals of antimicrobial stewardship are undermined when reported allergy to penicillin leads to the use of broad-spectrum antibiotics, increasing the risk of antimicrobial resistance 5.
Alternative Antibiotic Options
- Amoxicillin-clavulanate potassium is an effective treatment for infected cat or dog bites with no known bacterial cause 6.
- Pasteurella multocida is often resistant to typical empiric antibiotics used to treat skin infections, making amoxicillin-clavulanate potassium a suitable alternative 6.
- Antibiotic treatment should cover P. multocida, which is the dominating pathogen among patients with infected cat bites 7.