Recommended Antibiotic Treatment for Cat Scratch Disease
Azithromycin is the recommended first-line antibiotic 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
Treatment Algorithm
First-line Treatment:
- Azithromycin:
- Adults/patients >45 kg: 500 mg on day 1, then 250 mg daily for 4 days
- Children/patients <45 kg: 10 mg/kg on day 1, then 5 mg/kg daily for 4 days
Alternative Treatments:
- Erythromycin: 500 mg four times daily for 2 weeks to 2 months 1
- Doxycycline: 100 mg twice daily for 2 weeks to 2 months 1
- Ciprofloxacin: Has shown clinical efficacy 2
- Trimethoprim-sulfamethoxazole: Effective option, particularly for complicated cases 2
Special Considerations
For Complicated Infections:
- CNS involvement: Doxycycline with or without rifampin 1
- Immunocompromised patients: Extended treatment courses (>3 months) 1
- Diabetic patients: Amoxicillin-clavulanate 875/125 mg orally twice daily for 5-7 days 1
For Cat Bites/Scratches (Initial Prophylaxis):
- Amoxicillin-clavulanate: 875/125 mg twice daily 1
- For penicillin-allergic patients: Doxycycline 100 mg twice daily 1
Clinical Context
Cat scratch disease is caused by Bartonella henselae and typically presents with regional lymphadenopathy developing approximately 3 weeks after inoculation. A papule or pustule appears at the site of scratch/bite 3-30 days after exposure 1. While many cases are self-limited and may not require antibiotic treatment 3, treatment is recommended for:
- Severe or persistent symptoms
- Immunocompromised patients
- Disseminated disease
- Ocular involvement
- Neurologic manifestations
Evidence Quality and Considerations
The recommendation for azithromycin as first-line therapy is supported by the highest quality evidence. In a placebo-controlled study, azithromycin therapy was associated with more rapid reduction in size of infected lymph nodes 2. This aligns with more recent guidelines that rate the evidence for azithromycin as moderate to high 1.
It's important to note that lymphadenopathy may persist for 1-6 months despite appropriate treatment 1. Clinical reassessment within 24-48 hours is necessary for patients with worsening lymphangitis and edema.
Common Pitfalls to Avoid
Delayed diagnosis: Serology is the primary diagnostic method, but antibodies may not be detectable for up to 6 weeks after infection 1
Inadequate treatment duration: For complicated cases, especially in immunocompromised patients, treatment should be extended (minimum 3 months) 1
Overlooking prevention: Advise patients (especially immunocompromised) to:
- Avoid rough play with cats
- Keep cats' nails trimmed
- Implement proper flea control
- Wash hands thoroughly after handling cats 1
Missing atypical presentations: Cat scratch disease can present as Parinaud oculoglandular syndrome, neuroretinitis, persistent fever, hepatosplenic infection, encephalopathy, or osteomyelitis 2