From the Guidelines
For a cat bite infection in a patient with a penicillin allergy, I recommend starting empiric treatment with doxycycline 100mg twice daily for 5-7 days. This recommendation is based on the guidelines for the diagnosis and management of skin and soft-tissue infections, which suggest that doxycycline is an alternative oral agent for the treatment of cat bites 1. The patient's penicillin allergy necessitates alternative antibiotics that cover both aerobic and anaerobic organisms, and doxycycline is a suitable option.
Key Considerations
- The bite should be thoroughly cleaned with soap and water, and the hand should be elevated to reduce swelling.
- The patient should seek immediate medical attention as hand infections can rapidly worsen and may require surgical debridement.
- Cat bites are particularly concerning because they create deep puncture wounds that can introduce bacteria like Pasteurella multocida, which typically causes rapid onset of infection within 24-48 hours.
- Other options, such as trimethoprim-sulfamethoxazole or clindamycin, may also be considered, but doxycycline is a preferred choice due to its efficacy and safety profile.
- Tetanus prophylaxis should also be updated if needed.
Important Facts
- Cat bites have a higher proportion of osteomyelitis and septic arthritis compared to dog bites 1.
- First-generation cephalosporins, such as cephalexin, penicillinase-resistant penicillins, macrolides, and clindamycin, have poor in vitro activity against P. multocida and should be avoided 1.
- Amoxicillin-clavulanate is typically first-line therapy, but the penicillin allergy in this patient necessitates alternative antibiotics.
From the FDA Drug Label
Adults: The usual dose of oral doxycycline is 200 mg on the first day of treatment (administered 100 mg every 12 hours) followed by a maintenance dose of 100 mg/day In the management of more severe infections (particularly chronic infections of the urinary tract), 100 mg every 12 hours is recommended 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.
For an infected cat bite on the left hand in a patient with a PCN allergy, the recommended treatment is doxycycline. The dosage is 100 mg orally twice a day. The duration of treatment depends on the severity of the infection, but it is typically 7-14 days. It is essential to note that doxycycline is effective against a wide range of bacteria, including those commonly found in cat bites 2.
- Key points:
- Doxycycline is the recommended treatment for infected cat bites in patients with PCN allergy.
- The dosage is 100 mg orally twice a day.
- The duration of treatment is 7-14 days, depending on the severity of the infection.
- Doxycycline is effective against a wide range of bacteria, including those commonly found in cat bites 2.
From the Research
Infected Cat Bite on Left Hand with PCN Allergy
- The patient has a high risk of infection from the cat bite, as approximately 20-80% of all cat bites will become infected 3.
- The most commonly cultured bacterium from infected cat bite wounds is Pasteurella multocida 3, 4, 5.
- Given the patient's PCN allergy, alternative antibiotics such as amoxicillin-clavulanate potassium, cefazolin, or azithromycin may be considered for treatment 3, 4.
- It is essential to note that Pasteurella multocida can cause severe disease and even fatal outcomes, especially in immunocompromised individuals 5, 6.
- Prompt medical attention and appropriate treatment, including antibiotics and possibly surgical drainage or debridement, are crucial to prevent long-term disability and achieve good outcomes 7.
- The patient should be closely monitored for signs of infection, and clear guidelines for clinical recognition of infection, hospital admission, and management should be followed 7.