What is the recommended treatment for a cat scratch infection?

Treatment of Cat Scratch Infection

Azithromycin is the recommended first-line treatment for cat scratch disease, with a dosage of 500 mg on day 1 followed by 250 mg for 4 additional days for patients ≥45.5 kg, and 10 mg/kg on day 1 and 5 mg/kg for 4 more days for patients <45.5 kg. 1

Antibiotic Selection Based on Clinical Presentation

Typical Cat Scratch Disease

• For uncomplicated cases with lymphadenopathy:
  • Azithromycin is the treatment of choice, shown to reduce lymph node size with 80% regression at 30 days compared to placebo 1
  • Many uncomplicated cases in immunocompetent hosts are self-limiting and may not require antibiotic therapy 2

Complicated or Severe Presentations

• For patients with lymphangitis and progressive edema:

  • Broader coverage is necessary due to potential polymicrobial infection including Staphylococcus aureus and Streptococcal species 1
  • Prompt antibiotic therapy is essential to reduce inflammation quickly 1

• For diabetic patients:

  • Amoxicillin-clavulanate 875/125 mg orally twice daily for 5-7 days
  • Alternative for penicillin-allergic patients: doxycycline 100 mg twice daily 1

• For immunocompromised patients:

  • Extended treatment with erythromycin 500 mg four times daily or doxycycline 100 mg twice daily for 2 weeks to 2 months 1
  • Closer monitoring is required due to risk of developing bacillary angiomatosis 3

• For severe infection with high fever or extensive lymphadenopathy:

  • Hospitalization and IV antibiotics may be necessary 1

Clinical Monitoring and Follow-up

• Clinical reassessment within 24-48 hours for patients with worsening lymphangitis and edema 1
• Follow-up appointment in 1-2 weeks to assess symptom resolution 1
• Patients should be informed that lymphadenopathy may persist for 1-6 months despite appropriate treatment 1

Alternative Antibiotic Options

While azithromycin has the strongest evidence, other antibiotics with reported clinical efficacy include:

• Rifampin
• Ciprofloxacin
• Gentamicin
• Trimethoprim-sulfamethoxazole
• Clarithromycin 3

Prevention Strategies

• Immediate thorough washing of wounds with soap and water 1
• Implementation of flea control for cats (fleas are responsible for cat-to-cat transmission) 2
• Avoid rough play with cats and keep cats' nails trimmed 1
• Supervise children's interactions with cats 1
• Immunocompromised individuals should be especially cautious due to higher risk of severe infection 1

Important Clinical Considerations

• Cat scratch disease is caused by Bartonella henselae, a gram-negative bacillus 3
• Diagnosis is typically based on history of cat exposure and serologic testing with high titers (>1:256) of IgG antibody to B. henselae 2
• While typical presentation involves lymphadenopathy, atypical presentations can include Parinaud oculoglandular syndrome, neuroretinitis, persistent fever, hepatosplenic infection, encephalopathy, osteomyelitis, and endocarditis 3, 4