What is the recommended treatment for cat scratch fever?

Treatment of Cat Scratch Fever

Azithromycin is the recommended first-line treatment for cat scratch disease, with a dosing protocol of 500 mg on day 1 followed by 250 mg for 4 additional days for patients >45 kg, or 10 mg/kg on day 1 and 5 mg/kg for 4 more days for patients <45 kg. 1

Clinical Presentation and Diagnosis

Cat scratch disease (CSD) is caused by Bartonella henselae, a fastidious gram-negative bacillus transmitted through cat scratches or bites. The clinical presentation typically includes:

• A papule or pustule developing 3-30 days after a scratch or bite 1
• Regional lymphadenopathy occurring approximately 3 weeks after inoculation 1
• Lymphadenopathy generally resolving within 1-6 months, with suppuration in about 10% of cases 1
• Extranodal disease (affecting CNS, liver, spleen, bone, lung) developing in ≤2% of cases 1

Diagnosis is typically based on:

• History of cat exposure 2
• Serologic testing with high titers (>1:256) of IgG antibody to B. henselae 2
• PCR or Warthin-Starry silver stain of infected lymph node tissue in difficult cases 1

Treatment Algorithm

Immunocompetent Patients with Typical CSD

1. First-line treatment: Azithromycin

   • Adults >45 kg: 500 mg on day 1, then 250 mg daily for 4 days 1
   • Children <45 kg: 10 mg/kg on day 1, then 5 mg/kg daily for 4 days 1

2. Alternative treatments (if azithromycin is contraindicated):

   • Doxycycline 100 mg twice daily 1
   • Erythromycin 500 mg four times daily 1
   • Ciprofloxacin 500 mg twice daily 3
   • Trimethoprim-sulfamethoxazole 4

Immunocompromised Patients with Bacillary Angiomatosis

For immunocompromised patients (especially those with HIV/AIDS) who develop bacillary angiomatosis:

• First-line treatment: Erythromycin 500 mg four times daily or doxycycline 100 mg twice daily for 2 weeks to 2 months 1
• Alternative treatment: Clarithromycin or azithromycin 1
• Duration: Therapy should be administered for >3 months 1
• For CNS involvement: Doxycycline with or without rifampin 1

Prevention of Recurrence

• Long-term suppression with erythromycin or doxycycline should be considered for patients with relapse or reinfection 1
• For pregnant women requiring long-term suppression, erythromycin should be used (tetracyclines are contraindicated during pregnancy) 1

Evidence Quality and Treatment Efficacy

The recommendation for azithromycin is based on a placebo-controlled study showing more rapid reduction in lymph node size (80% regression at 30 days) in patients receiving azithromycin compared to placebo (P = .02) 1. This represents the strongest evidence available for treatment efficacy.

Most cases of cat scratch disease in immunocompetent hosts are self-limited and may not require antibiotic therapy 4, 2. However, treatment is recommended for:

• Severe or persistent cases 5
• Patients with systemic symptoms 2
• Immunocompromised patients 1
• Cases with extranodal or disseminated disease 1

Prevention Measures

For prevention of Bartonella infection, especially in immunocompromised individuals:

• Consider risks of cat ownership, particularly for severely immunosuppressed persons 1
• If acquiring a cat, choose one >1 year old in good health 1
• Avoid rough play with cats 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

Special Considerations

• Children: The same treatment recommendations apply, with weight-based dosing for azithromycin 1
• Pregnant women: Erythromycin is preferred; tetracyclines should be avoided 1
• HIV-infected patients: More aggressive and prolonged treatment is needed, particularly for bacillary angiomatosis 1