What is the treatment for cat scratch disease?

Treatment of Cat Scratch Disease

Azithromycin is the first-line antibiotic 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 daily for 4 more days in patients <45 kg. 1

When to Treat vs. Observe

Most immunocompetent patients with uncomplicated cat scratch disease do not require antibiotics, as the condition is self-limited and resolves within 1-6 months. 2, 3 However, treatment is indicated in specific circumstances:

• Treat immunocompromised patients (particularly those with HIV and CD4+ <100 cells/µL) due to risk of disseminated disease including bacillary angiomatosis, peliosis hepatis, and CNS involvement 1
• Treat extranodal or disseminated disease (hepatosplenic involvement, encephalopathy, retinitis, endocarditis, osteomyelitis) 1
• Consider treatment for severe or persistent lymphadenopathy causing significant symptoms or quality of life impairment 1

First-Line Antibiotic Therapy

Azithromycin is the preferred agent based on placebo-controlled evidence showing more rapid reduction in lymph node size: 1, 2

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

Alternative Antibiotic Options

If azithromycin is contraindicated, use: 1

• Doxycycline 100 mg twice daily for 10-14 days (adults) 1, 4
  • Children <45 kg: 2.2 mg/kg twice daily (max 100 mg/dose) for 10-14 days 4
  • Avoid in pregnancy and use with extreme caution in children only if no alternatives exist 1
• Erythromycin 500 mg four times daily 1
  • This is the only safe option for pregnant women 1

Other effective agents with clinical evidence include rifampin, ciprofloxacin, gentamicin, trimethoprim-sulfamethoxazole, and clarithromycin, though these are not first-line. 2, 5

Treatment for Severe/Disseminated Disease

For CNS bartonellosis and other severe infections, use doxycycline with or without rifampin for extended duration (>3 months). 1

For HIV-infected patients with bacillary angiomatosis, peliosis hepatis, or CNS involvement, treat with erythromycin or doxycycline for more than 3 months. 1

Gentamicin has shown 73% efficacy with rapid response within 48 hours for severe cases with hepatosplenic involvement. 1

Prevention of Recurrence

Long-term suppression with erythromycin or doxycycline should be considered for patients with relapse or reinfection. 6, 1

For HIV patients, continue suppressive therapy until CD4+ >200 cells/µL for >6 months. 1

Critical Pitfalls to Avoid

• Do not use penicillins or first-generation cephalosporins—they have no in vivo activity against Bartonella 1
• Quinolones and TMP-SMX have variable activity and inconsistent clinical response—not recommended as first-line 1
• Serologic testing may be falsely negative if performed <6 weeks after infection 1, 7
• In advanced HIV (CD4+ <100), up to 25% of culture-positive patients never develop antibodies—do not rely on serology alone 1
• Do not test cats for Bartonella—this provides no clinical benefit 7, 4

Special Populations

Children: Same treatment algorithm with weight-based azithromycin dosing; fluoroquinolones only if absolutely no alternatives exist 1, 7

Pregnant women: Erythromycin only; tetracyclines (doxycycline) are absolutely contraindicated 6, 1

Immunocompromised: More aggressive evaluation and treatment required; consider Bartonella in any HIV patient with unexplained fever and CD4+ <100 cells/µL 1

Prevention Measures

• Avoid rough play with cats and situations where scratches are likely 6, 1
• Promptly wash any cat-associated wounds 6, 1
• Implement comprehensive flea control for cats 6, 1
• Do not allow cats to lick open wounds 6, 1
• Consider adopting cats >1 year old in good health 6, 1
• Severely immunosuppressed persons should carefully consider the risks of cat ownership 6, 1