What is the treatment for a cat scratch?

Treatment of Cat Scratch

For a simple cat scratch without signs of infection, immediate thorough wound irrigation with soap and water is the most critical intervention, followed by topical antibiotic ointment and occlusive dressing—antibiotics are reserved only for documented cat scratch disease with lymphadenopathy or signs of invasive infection. 1, 2, 3

Immediate Wound Management

All cat scratches require aggressive initial wound care regardless of infection status:

• Irrigate immediately with high-volume (100-1000 mL) soap and water to reduce bacterial load and prevent Bartonella henselae transmission 1, 3
• Add povidone-iodine solution as a virucidal agent, particularly important for stray cat exposures where rabies risk exists 1, 3
• Apply topical antibiotic ointment and cover with clean occlusive dressing, changing daily 3
• Update tetanus immunization if not current 2, 3

Rabies Risk Assessment (Critical for Stray Cats)

If the cat is a stray and cannot be observed for 10 days or tested, initiate rabies postexposure prophylaxis immediately with both rabies immune globulin (RIG) and vaccine series—do not delay. 1, 3

• Documented or owned cats in good health can be observed for 10 days 1
• Stray cats have unknown vaccination status and higher Bartonella infection rates 3

When to Use Antibiotics

Most simple cat scratches do NOT require antibiotics and resolve spontaneously. 1, 4, 5 Antibiotic therapy is indicated only when:

For Cat Scratch Disease (Lymphadenopathy Present)

Azithromycin is the first-line antibiotic when regional lymphadenopathy develops (typically 1-3 weeks post-scratch): 1

• Patients >45 kg: 500 mg on day 1, then 250 mg daily for 4 additional days 1, 2
• Patients <45 kg: 10 mg/kg on day 1, then 5 mg/kg daily for 4 additional days 1, 3
• This regimen speeds lymph node regression but does not dramatically alter the self-limited course 1

For Invasive Soft Tissue Infection

If signs of invasive bacterial infection develop (erythema >5 cm, warmth, purulent drainage, fever ≥38.5°C, or lymphangitis), treat with: 2

• First-line oral: Amoxicillin-clavulanate 875 mg twice daily for 7-10 days 1, 2
• Severe/hospitalized: Ampicillin-sulbactam 1.5-3.0 g IV every 6-8 hours 1, 2
• Penicillin-allergic: Doxycycline 100 mg twice daily (excellent activity against Pasteurella multocida) 1

Critical pitfall: Never use first-generation cephalosporins (cephalexin) for cat bites/scratches—they have poor activity against Pasteurella multocida, the most common pathogen. 2

Immunocompromised Patients

HIV-infected or immunocompromised patients who develop bacillary angiomatosis (red papules or subcutaneous nodules) require prolonged therapy: 1

• Erythromycin 500 mg four times daily OR doxycycline 100 mg twice daily for 2 weeks to 2 months 1
• These patients are at risk for life-threatening disseminated disease 6

Red Flags Requiring Urgent Evaluation

Seek immediate medical attention if any of the following develop: 2, 3

• Increasing erythema, swelling, warmth, or pain around the wound 3
• Red streaks extending from wound (lymphangitis) 2, 3
• Fever or systemic symptoms 2
• Lymph node enlargement (typically 1-3 weeks post-scratch) 1, 3
• Neurologic symptoms (encephalopathy occurs in <2% of cases) 1
• Hepatosplenic symptoms or persistent fever 2, 5

Follow-Up and Monitoring

• Reassess in 48-72 hours if antibiotics were started to ensure clinical improvement 2
• Lymphadenopathy from cat scratch disease typically resolves within 1-6 months even without treatment 1, 4
• Monitor for rare complications: encephalopathy, hepatosplenic involvement, osteomyelitis, or endocarditis 2, 5, 7

Key Clinical Pearls

• Most cat scratches are self-limited and require only wound care—not antibiotics 4, 5, 7
• Azithromycin is reserved for documented cat scratch disease with lymphadenopathy 1
• Stray cat scratches mandate rabies risk assessment 1, 3
• Amoxicillin-clavulanate covers both Pasteurella and Bartonella for invasive infections 1, 2