Treatment for Cat Scratch Disease (Bartonella henselae Infections)
Azithromycin is the recommended first-line treatment for infections caused by cat scratches (Bartonella henselae), with a dosage of 500 mg on day 1 followed by 250 mg for 4 additional days for patients >45 kg. 1
First-Line Treatment Options
Azithromycin Regimen
- Adults >45 kg: 500 mg on day 1, then 250 mg daily for 4 more days
- Children <45 kg: 10 mg/kg on day 1, then 5 mg/kg daily for 4 more days 1
Alternative First-Line Options
- Erythromycin: 500 mg four times daily for 2 weeks to 2 months 1
- Doxycycline: 100 mg twice daily for 2 weeks to 2 months 1
Special Clinical Scenarios
Severe or Complicated Infections
For severe infections or those with extranodal manifestations:
- Treatment duration: Minimum 3 months recommended 1
- CNS involvement: Doxycycline with or without rifampin is preferred 1
- Immunocompromised patients: Longer treatment courses (>3 months) are recommended 2
Diabetic Patients
- Amoxicillin-clavulanate: 875/125 mg orally twice daily for 5-7 days 1
- Doxycycline: 100 mg twice daily (for penicillin-allergic patients) 1
Treatment Considerations
Important Caveats
- Penicillins and first-generation cephalosporins have no in vivo activity and should not be used 2, 1
- Quinolones and TMP-SMX have variable in vitro activity and inconsistent clinical response and are not recommended 2
- For immunocompetent patients with uncomplicated cat scratch disease, the infection is often self-limited and may not necessarily require antibiotic therapy 3
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
Prevention Strategies
Risk Reduction
- Wash cat scratches promptly with soap and water 1
- Implement comprehensive flea control for cats (cats are the main reservoir) 1
- Avoid rough play with cats and keep cats' nails trimmed 1
- Do not allow cats to lick open wounds 1
High-Risk Individuals
- Immunocompromised persons (especially those with HIV and CD4+ <100 cells/μL) should consider the risks of cat ownership 2, 1
- If acquiring a cat, choose one >1 year old and in good health 2, 1
Clinical Pearls
- Cat scratch disease typically presents as regional lymphadenopathy developing approximately 3 weeks after inoculation 1
- Suppuration occurs in about 10% of cases 1
- Extranodal manifestations (CNS involvement, hepatosplenic infection, osteomyelitis, endocarditis) occur in ≤2% of cases 1
- Serology is the primary diagnostic method, though antibodies may not be detectable for up to 6 weeks after infection 1