What is the recommended treatment for a patient presenting with a cat scratch and symptoms of left lower extremity edema and lymphangitis?

Treatment Management for Cat Scratch with Lymphangitis and Lower Extremity Edema

For a patient presenting to the ER with a cat scratch 2 days prior and symptoms of left lower extremity edema and lymphangitis, azithromycin is the first-line treatment, with a recommended dosage of 500 mg on day 1 followed by 250 mg once daily for 4 additional days. 1

Diagnosis and Assessment

• Confirm cat scratch disease (CSD) based on:
  • Recent history of cat scratch (2 days prior)
  • Presence of lymphangitis and edema
  • Look for a papule or pustule at the scratch site

Treatment Algorithm

First-line Treatment:

• Azithromycin:
  • For patients ≥45.5 kg: 500 mg on day 1, then 250 mg once daily for 4 additional days
  • For patients <45.5 kg: 10 mg/kg on day 1, then 5 mg/kg daily for days 2-5 2, 1, 3

Alternative Treatments (if azithromycin contraindicated):

• Doxycycline: 100 mg twice daily for 5-7 days 1
• Amoxicillin-clavulanate: 875/125 mg orally twice daily for 5-7 days (especially for diabetic patients) 1

Evidence and Rationale

The recommendation for azithromycin is based on a double-blind, placebo-controlled study showing that lymph node size regressed by 80% at 30 days more frequently in azithromycin-treated patients compared to placebo (P = .02) 2, 1. This is particularly important for this patient with lymphangitis and edema, as reducing inflammation quickly is essential.

While cat scratch disease is often self-limited in immunocompetent hosts 4, the presence of lymphangitis and edema indicates a more significant infection that warrants antibiotic therapy. The Infectious Diseases Society of America guidelines support azithromycin as the treatment of choice 2, 1.

Special Considerations

• Immunocompromised patients: For patients with HIV or other immunocompromised conditions, consider longer treatment duration and closer monitoring due to risk of developing bacillary angiomatosis 1

• Diabetic patients: Consider amoxicillin-clavulanate as it provides broader coverage for potential polymicrobial infection 1

• Severe infection: If patient shows signs of systemic illness (high fever, extensive lymphadenopathy), consider hospitalization and IV antibiotics

Prevention of Recurrence

• Advise proper wound care for any future cat scratches:
  • Immediate thorough washing with soap and water 1
  • Implement flea control for cats 1
  • Avoid rough play with cats and keep cats' nails trimmed 1

Follow-up

• Schedule follow-up in 1-2 weeks to assess resolution of symptoms
• Inform patient that lymphadenopathy may persist for 1-6 months despite appropriate treatment 2
• Advise to return sooner if symptoms worsen or new symptoms develop

Azithromycin is the clear treatment of choice based on the most recent and highest quality evidence, with demonstrated efficacy in reducing the inflammatory response associated with cat scratch disease, which is particularly important for this patient's presentation with lymphangitis and edema.