From the Guidelines
For a patient with cat scratch cellulitis who is allergic to penicillin and Zosyn, the recommended treatment is azithromycin 500 mg on day 1, then 250 mg once daily for 4 additional days. This recommendation is based on a study published in the Clinical Infectious Diseases journal in 2014 1, which found that azithromycin treatment resulted in significant regression of lymph node size in patients with cat scratch disease. The dose of azithromycin for patients weighing ≥45.5 kg is 500 mg on day 1, then 250 mg once daily for 4 additional days, while for those weighing <45.5 kg, the dose is 10 mg/kg orally on day 1, then 5 mg/kg on days 2–5.
Some key points to consider in the treatment of cat scratch cellulitis include:
- The primary causative organism of cat scratch disease is Bartonella henselae, which is susceptible to azithromycin
- Treatment with antimicrobial agents can help reduce symptom duration and prevent complications, particularly in immunocompromised patients
- Local wound care and warm compresses should be used in conjunction with antibiotic therapy
- Patients should be monitored for improvement within 48-72 hours, and treatment may need adjustment if symptoms worsen or fail to improve
It's worth noting that while doxycycline and fluoroquinolones are alternative options for treating cat scratch disease, azithromycin is a preferred choice due to its efficacy and safety profile, as demonstrated in the 2014 study 1. Additionally, azithromycin is a suitable option for children and pregnant women, where doxycycline is contraindicated.
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
- Doxycycline is recommended for the treatment of various infections, but the label does not specifically mention cat scratch cellulitis.
- However, considering the patient's allergy to penicillin and Zosyn (piperacillin/tazobactam), doxycycline may be a suitable alternative for the treatment of cat scratch cellulitis, which is typically caused by Bartonella henselae.
- The recommended dose of doxycycline for adults is 100 mg/day, but the label does not provide specific guidance for the treatment of cat scratch cellulitis.
- Given the lack of specific guidance, a conservative approach would be to use the recommended dose for other infections, which is 100 mg/day 2.
From the Research
Treatment Options for Cat Scratch Cellulitis
In a patient with cat scratch cellulitis who is allergic to penicillin and Zosyn (piperacillin/tazobactam), the following treatment options can be considered:
- Azithromycin: This antibiotic has been shown to be effective in treating cat scratch disease, with one study demonstrating more rapid diminution in size of infected lymph nodes 3. Another study found that azithromycin was associated with resolution and improvement of CSD in 51.4% of patients 4.
- Trimethoprim/sulfamethoxazole (TMP/SMX): This antibiotic combination has also been found to be effective in treating CSD, with a study showing that it was associated with resolution and improvement of CSD in 61.5% of patients 4.
- Ciprofloxacin: This antibiotic has been shown to be effective against Bartonella henselae, the causative agent of cat scratch disease, in vitro 3.
- Gentamicin: This antibiotic has also been shown to be effective against B. henselae in vitro 3.
- Clarithromycin: This antibiotic has been found to be effective in treating CSD, with one study demonstrating its efficacy in treating the disease 3.
Key Considerations
When treating a patient with cat scratch cellulitis who is allergic to penicillin and Zosyn, it is essential to consider the following:
- The patient's allergy history and potential cross-reactivity with other antibiotics
- The severity of the disease and the need for prompt treatment
- The potential for complications, such as hepatosplenomegaly or meningoencephalitis, and the need for close monitoring
- The effectiveness of alternative antibiotics, such as azithromycin and TMP/SMX, in treating CSD 4