What is the treatment for a cat scratch?

Treatment of Cat Scratch Injuries

Immediate Wound Management

Thoroughly cleanse the cat scratch with sterile normal saline immediately after injury, then initiate prophylactic antibiotics for high-risk wounds. 1

Initial Wound Care

• Irrigate the wound with sterile normal saline to remove superficial debris and reduce bacterial load 1
• Deeper debridement is unnecessary unless significant devitalized tissue is present 1
• Evaluate and update tetanus immunization status at the time of injury 1
• Consider rabies risk assessment if the cat is unknown, feral, or behaving abnormally 1

When to Prescribe Prophylactic Antibiotics

Prescribe prophylactic antibiotics for:

• Deep wounds or puncture injuries 1
• Wounds on hands, feet, face, or near joints 1
• Immunocompromised patients (including diabetics) 1
• Any wound with signs of developing infection 1

Cat scratches carry a 10-20% infection risk, making prophylaxis critical for high-risk presentations 1

Antibiotic Selection

First-Line Therapy

Amoxicillin-clavulanate is the first-line prophylactic antibiotic, providing coverage against Pasteurella multocida and other common pathogens from cat scratches 1

Alternative Regimens for Penicillin Allergy

• Doxycycline 100 mg twice daily (adults) - excellent activity against Pasteurella multocida 1
• Trimethoprim-sulfamethoxazole plus metronidazole (for anaerobic coverage) 1
• Fluoroquinolones (ciprofloxacin 500-750 mg twice daily) with consideration for additional anaerobic coverage 1

Duration of Prophylaxis

• Standard duration: 1-2 weeks for mild soft tissue infections 1
• Extended duration: 3-4 weeks if infection is extensive, resolving slowly, or patient has severe peripheral artery disease 1
• Diabetic patients require more aggressive treatment due to impaired immune response and delayed wound healing 1

Treatment of Cat Scratch Disease (Bartonella henselae)

If the patient develops regional lymphadenopathy approximately 3 weeks after the scratch, suspect cat scratch disease caused by Bartonella henselae 2

Antibiotic Treatment for Cat Scratch Disease

Azithromycin is the first-line treatment for cat scratch disease:

• Patients >45 kg: 500 mg on day 1, then 250 mg daily for 4 additional days 2
• Patients <45 kg: 10 mg/kg on day 1, then 5 mg/kg daily for 4 additional days 2

This recommendation is based on a placebo-controlled study showing more rapid reduction in lymph node size with azithromycin 2, 3

Alternative Antibiotics for Cat Scratch Disease

• Doxycycline 100 mg twice daily if azithromycin is contraindicated 2
• Erythromycin 500 mg four times daily if azithromycin is contraindicated 2
• Erythromycin is preferred for pregnant women, as tetracyclines are contraindicated during pregnancy 2

When to Treat Cat Scratch Disease

Treatment is mandatory for:

• Immunocompromised patients 2
• Extranodal or disseminated disease 2
• Severe symptoms or complications 2

Most cases in immunocompetent patients are self-limited and resolve within 1-6 months without antibiotics, though treatment speeds recovery 2, 4

Special Populations and Severe Disease

Immunocompromised Patients (HIV/AIDS)

For bacillary angiomatosis, peliosis hepatis, or CNS involvement:

• Erythromycin or doxycycline for more than 3 months 2
• Doxycycline with or without rifampin is the treatment of choice for CNS bartonellosis and other severe infections 2
• Up to 25% of culture-positive HIV patients with CD4+ <100 cells/µL may never develop antibodies, complicating diagnosis 2

Diabetic Patients

• Require more aggressive treatment with 1-2 weeks minimum antibiotic therapy 1
• Consider extending to 3-4 weeks if extensive infection or delayed healing 1
• Provide optimal wound care including debridement of necrotic tissue and off-loading of pressure 1
• Seek urgent surgical consultation for deep abscess, extensive necrosis, or necrotizing fasciitis 1

Critical Pitfalls to Avoid

• Do not use penicillins or first-generation cephalosporins alone for Bartonella infections - they have no in vivo activity 2
• Do not use quinolones or TMP-SMX for cat scratch disease - they have variable activity and inconsistent clinical response 2
• Do not test cats for Bartonella infection - this provides no diagnostic or management benefit 2
• Serologic testing may be falsely negative if performed <6 weeks after acute infection 2
• Elevation of the injured extremity accelerates healing if swelling is present 1

Follow-Up Instructions

Instruct patients to return immediately if:

• Increasing pain, redness, or swelling develops 1
• Purulent drainage appears 1
• Fever develops 1
• Lymph nodes become enlarged or tender 2

Monitor for complications including septic arthritis, osteomyelitis, or tendonitis, especially with hand wounds 1