What is the recommended treatment for cat scratch fever?

Treatment of Cat Scratch Fever

Azithromycin is the first-line antibiotic treatment for cat scratch disease, dosed at 500 mg on day 1 followed by 250 mg daily for 4 additional days in patients >45 kg, or 10 mg/kg on day 1 and 5 mg/kg for 4 more days in patients <45 kg. 1

When to Treat vs. Observe

Most cases of cat scratch disease in immunocompetent patients are self-limited and resolve without antibiotics within 1-6 months 1. However, treatment is specifically indicated for:

• Immunocompromised patients (especially HIV/AIDS with CD4+ <100 cells/µL) 1
• Extranodal or disseminated disease (hepatosplenic involvement, CNS disease, bacillary angiomatosis) 1
• Severe or persistent lymphadenopathy where more rapid resolution is desired 1, 2
• Systemic symptoms with fever ≥38.5°C or pulse ≥100 bpm 3

Treatment Algorithm by Clinical Scenario

Standard Cat Scratch Disease (Immunocompetent)

• Azithromycin 500 mg day 1, then 250 mg daily × 4 days (>45 kg) 1, 4
• Azithromycin 10 mg/kg day 1, then 5 mg/kg daily × 4 days (<45 kg) 1, 4
• This regimen accelerates lymph node size reduction compared to placebo 1

Alternative Antibiotics (if azithromycin contraindicated)

• Doxycycline 100 mg twice daily 1
• Erythromycin 500 mg four times daily 1
• Ciprofloxacin has shown efficacy in case reports but is not first-line 5

Severe/Disseminated Disease

• Doxycycline with or without rifampin for CNS bartonellosis and severe infections 1
• Gentamicin for hepatosplenic involvement (73% efficacy with rapid response within 48 hours) 1
• Extended therapy >3 months for HIV patients with bacillary angiomatosis, peliosis hepatis, or CNS involvement 1

Special Populations

Pregnant Women:

• Erythromycin only - tetracyclines (doxycycline) are absolutely contraindicated 1

HIV/AIDS Patients:

• Erythromycin or doxycycline for >3 months 1
• Continue suppressive therapy until CD4+ >200 cells/µL for >6 months 1
• Up to 25% may never develop antibodies despite active infection 1

Children:

• Same weight-based azithromycin dosing as above 1
• Fluoroquinolones only if no alternatives exist 1

Critical Pitfalls to Avoid

• Never use penicillins or first-generation cephalosporins (cephalexin) - they have no in vivo activity against Bartonella 1, 3
• Avoid quinolones and TMP-SMX - variable activity and inconsistent clinical response 1
• Do not test cats for Bartonella - provides no diagnostic or management benefit 1
• Serologic testing may be falsely negative if performed <6 weeks after infection 1
• In advanced HIV (CD4+ <100), 25% never develop antibodies - absence of antibodies does not exclude infection 1

Adjunctive Management

• Thoroughly cleanse any open wounds with sterile saline 3
• Update tetanus immunization if not current 3
• Elevate affected extremity to reduce swelling 3
• Reassess in 48-72 hours to ensure antibiotic efficacy 3
• Monitor for complications: septic arthritis, osteomyelitis, hepatosplenic involvement 3

Prevention Measures

• Choose cats >1 year old in good health 1
• Avoid rough play and situations where scratches are likely 1
• Promptly wash any cat-associated wounds 1
• Implement comprehensive flea control for cats 1
• Do not allow cats to lick open wounds 1
• Severely immunosuppressed persons should consider risks of cat ownership 1