What is the recommended antibiotic for cat scratch fever (Bartonella henselae infection)?

Antibiotic Treatment for Cat Scratch Fever

First-Line Recommendation

Azithromycin is the recommended first-line antibiotic for cat scratch disease (Bartonella henselae infection), 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 daily for 4 more days in patients <45 kg. 1

This recommendation comes from the American College of Physicians and is based on a placebo-controlled study demonstrating more rapid reduction in lymph node size compared to placebo. 1, 2

When to Treat vs. Observe

• Most immunocompetent patients with uncomplicated cat scratch disease do not require antibiotic therapy, as the condition is typically self-limited with lymphadenopathy resolving within 1-6 months. 2, 3

• Treatment is specifically indicated for:

  • Immunocompromised patients 1
  • Cases with extranodal or disseminated disease (CNS, liver, spleen, bone, lung involvement) 1
  • Severe or persistent symptoms 4
  • Bacillary angiomatosis in HIV/AIDS patients 5

Alternative Antibiotic Options

If azithromycin is contraindicated or unavailable:

• Doxycycline 100 mg twice daily is recommended by the CDC as an alternative. 1, 6 The FDA label specifically lists bartonellosis as an approved indication for doxycycline. 6

• Erythromycin 500 mg four times daily is another CDC-recommended alternative. 1

• For pregnant women, erythromycin should be used instead of tetracyclines, which are contraindicated during pregnancy. 1

Special Clinical Scenarios

Severe Bartonellosis in Immunocompromised Patients

For HIV-infected patients with bacillary angiomatosis, peliosis hepatis, or CNS involvement:

• Erythromycin or doxycycline for >3 months is recommended based on case series experience. 5

• Doxycycline with or without rifampin is the treatment of choice for CNS bartonellosis and other severe infections. 5

• Clarithromycin or azithromycin can be alternatives for patients unlikely to comply with more frequent dosing schedules. 5

Agents to Avoid

• Penicillins and first-generation cephalosporins have no in vivo activity and should not be used for bartonellosis treatment. 5

• Quinolones and TMP-SMX have variable in vitro activity and inconsistent clinical response; they are not recommended. 5

Treatment Duration and Monitoring

• Standard course: 5 days for azithromycin in immunocompetent patients 1

• Extended therapy: >3 months for severe bartonellosis in immunocompromised patients 5

• Long-term suppression with erythromycin or doxycycline should be considered for patients with relapse or reinfection. 1

Clinical Pitfalls

• Do not confuse initial wound management (which may require amoxicillin-clavulanate for polymicrobial cat scratch/bite wound infections) with treatment of established cat scratch disease caused by B. henselae. 7

• Serologic testing may not show detectable antibodies until 6 weeks after acute infection in immunocompetent patients. 5

• In advanced HIV infection, up to 25% of culture-positive patients may never develop antibodies. 5

• Cross-reactivity can occur between B. henselae and B. quintana on serologic testing. 8, 9