What is the treatment for cat scratch fever?

Treatment for Cat Scratch Fever

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 kg, or 10 mg/kg on day 1 and 5 mg/kg for 4 more days for patients <45 kg. 1

Overview of Cat Scratch Disease

Cat scratch disease (CSD) is caused by Bartonella henselae, a gram-negative bacterium transmitted primarily through cat scratches or bites. The disease typically presents with:

• A papule or pustule at the inoculation site 3-30 days after exposure
• Regional lymphadenopathy occurring approximately 3 weeks after inoculation
• Lymph node enlargement that may persist for 1-6 months
• Suppuration of lymph nodes in about 10% of cases
• Occasional extranodal manifestations (CNS, liver, spleen, bone, lung) in ≤2% of cases

Treatment Algorithm

For Typical Cat Scratch Disease (Uncomplicated Lymphadenopathy)

1. First-line therapy: Azithromycin

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

2. Alternative therapies (if azithromycin is contraindicated):

   • Doxycycline 100 mg twice daily 1, 2
   • Erythromycin 500 mg four times daily 1, 3
   • Trimethoprim-sulfamethoxazole 2
   • Ciprofloxacin 2

For Complicated or Disseminated Disease

• For immunocompromised patients with bacillary angiomatosis:

  • Erythromycin 500 mg four times daily or doxycycline 100 mg twice daily for 2 weeks to 2 months 1

• For patients with hepatosplenic involvement or severe systemic disease:

  • Consider gentamicin, particularly for hepatic involvement 4
  • Rifampin may be effective for disseminated disease 2

Evidence-Based Considerations

The 2014 Infectious Diseases Society of America (IDSA) guidelines provide strong, moderate-quality evidence supporting azithromycin as the treatment of choice 1. This recommendation is based on a controlled study showing that azithromycin therapy was associated with more rapid reduction in lymph node size compared to placebo 1, 2.

Most cases of cat scratch disease in immunocompetent hosts are self-limited and may not require antibiotic therapy 3, 5, 2. However, treatment should be considered for:

• Severe or persistent symptoms
• Lymphadenopathy that is painful or suppurative
• Systemic manifestations or complications
• Immunocompromised patients

Special Populations

Immunocompromised Patients

• At higher risk for developing bacillary angiomatosis or peliosis hepatis
• Require longer treatment courses (2 weeks to 2 months) 1
• May need long-term suppression with erythromycin or doxycycline if relapse occurs 1

Pregnant Women

• If treatment is required, erythromycin is preferred
• Tetracyclines (including doxycycline) should be avoided during pregnancy 1

Clinical Pearls and Pitfalls

• Diagnostic challenge: B. henselae is difficult to culture, so diagnosis often relies on clinical presentation, history of cat exposure, and serologic testing (IgG titers >1:256) 5

• Prolonged fever: Children with CSD who have prolonged fever (>7 days) should be evaluated for complications such as hepatosplenic involvement or CNS disease 6

• Treatment duration: While a 5-day course of azithromycin is standard for uncomplicated disease, complicated cases may require 2-4 weeks of therapy

• Prevention: HIV-infected and immunocompromised individuals should be counseled about the risks of cat ownership, particularly with kittens. If they do own cats, they should avoid rough play, promptly clean scratches, and maintain flea control 1