If a patient presents with a cat scratch and worsening left lower extremity (LLE) edema with lymphangitis, while already on azithromycin (Azithromycin), is additional antibiotic (abx) therapy indicated?

Management of Cat Scratch Disease with Lymphangitis and Lower Extremity Edema

For a patient with cat scratch disease presenting with worsening left lower extremity edema and lymphangitis who is already on azithromycin, additional antibiotic therapy is indicated to provide broader coverage against potential secondary bacterial pathogens.

Recommended Treatment Approach

Current Situation Assessment

• Patient has confirmed cat scratch disease (Bartonella henselae infection)
• Currently on azithromycin (first-line therapy for cat scratch disease)
• Developing worsening lymphangitis and edema in left lower extremity
• These progressive symptoms suggest possible secondary bacterial infection

Additional Antibiotic Recommendations

1. Add an anti-staphylococcal antibiotic:

   • First choice: Amoxicillin-clavulanate 875/125 mg orally twice daily for 5-7 days 1
   • For penicillin-allergic patients: Doxycycline 100 mg twice daily 1

2. Continue current azithromycin therapy:

   • Complete the full course (500 mg on day 1, followed by 250 mg for 4 additional days) 1, 2

Rationale for Additional Antibiotic Coverage

• Lymphangitis with progressive edema suggests potential secondary bacterial infection beyond Bartonella

• Skin and soft tissue infections following animal contact often involve polymicrobial pathogens including:

  • Staphylococcus aureus (including potential MRSA)
  • Streptococcal species
  • Other gram-negative organisms

• The Infectious Diseases Society of America (IDSA) guidelines for skin and soft tissue infections recommend broader coverage when lymphangitis and progressive edema are present 3

Monitoring and Follow-up

• Clinical reassessment within 24-48 hours to evaluate response

• If symptoms worsen despite oral antibiotics (increasing edema, spreading erythema, systemic symptoms):

  • Consider hospitalization for IV antibiotics 1
  • Consider imaging to rule out deeper infection or abscess formation

• Patients with lymphangitis and edema require prompt and effective antibiotic therapy to reduce inflammation quickly 1

Special Considerations

• If the patient is immunocompromised, a longer treatment duration may be required (2 weeks to 2 months) 1
• Diabetic patients particularly benefit from amoxicillin-clavulanate coverage 1
• Lymphadenopathy from cat scratch disease may persist for 1-6 months despite appropriate treatment 1

Prevention of Recurrence

• Proper wound care for any future cat scratches (immediate washing with soap and water)
• Implement flea control for cats
• Avoid rough play with cats and keep cats' nails trimmed 1

This approach provides targeted coverage for both the primary Bartonella infection and potential secondary bacterial pathogens that may be contributing to the worsening lymphangitis and edema, optimizing the chance for clinical improvement and preventing further complications.