What is the recommended treatment for cellulitis resulting from a cat bite?

Treatment of Cellulitis from Cat Bite

For cellulitis resulting from a cat bite, amoxicillin-clavulanate is the first-line antibiotic treatment due to its excellent coverage against Pasteurella multocida and other common bite wound pathogens. 1

Microbiology and Pathogen Considerations

Cat bites introduce a polymicrobial mix of bacteria including:

• Pasteurella multocida (most common pathogen)
• Staphylococcus species
• Streptococcus species
• Anaerobic bacteria

Unlike typical cellulitis which is primarily caused by streptococci or staphylococci, cat bite cellulitis requires specific antibiotic coverage for P. multocida, which is present in 50-80% of cat bite infections.

First-Line Treatment

• Oral therapy: Amoxicillin-clavulanate 875/125 mg twice daily 1
• Parenteral therapy (for severe infections): Ampicillin-sulbactam, piperacillin-tazobactam, or ertapenem 2
• Duration: 5-7 days for uncomplicated infections; extend if no improvement 2

Alternative Regimens for Penicillin-Allergic Patients

For patients with penicillin allergy, the following options are recommended:

• Doxycycline (excellent alternative) 1
• Clindamycin plus a fluoroquinolone 1
• Trimethoprim-sulfamethoxazole plus metronidazole 1

Important Cautions

• Avoid monotherapy with:
  • First-generation cephalosporins (cephalexin)
  • Penicillinase-resistant penicillins (dicloxacillin)
  • Macrolides
  • Clindamycin alone

These antibiotics have poor activity against P. multocida and should not be used as monotherapy for cat bite cellulitis 2, 1.

Wound Management

1. Immediate wound care:

   • Thorough cleansing with sterile normal saline
   • Removal of superficial debris
   • Elevation of affected area 1

2. Wound closure considerations:

   • Facial wounds may be closed primarily with prophylactic antibiotics
   • For wounds >8 hours old, consider delayed primary closure
   • Wounds with established infection should not be closed 1

Indications for Hospitalization

Consider inpatient treatment for:

• Severe infections with systemic symptoms
• Deep infections involving tendons or joints
• Hand infections
• Immunocompromised patients with moderate to severe infections 1

Follow-up and Monitoring

• Assess response within 24-48 hours
• Monitor for signs of worsening infection
• If no improvement after 5 days, extend treatment duration 2

Special Considerations

• Hand infections: These carry higher risk and may require surgical consultation
• Immunocompromised patients: May require broader spectrum antibiotics and closer monitoring
• Severe infections: Consider blood cultures and parenteral therapy 1

Unusual Pathogens

If the infection doesn't respond to appropriate first-line therapy, consider:

• Resistant organisms
• Atypical pathogens (rare cases of Mycobacterium chelonae have been reported) 3
• Secondary conditions that mimic cellulitis 4

Cat bite cellulitis requires prompt treatment with appropriate antibiotics to prevent complications such as bacteremia and sepsis, which can occur rapidly as demonstrated in case reports 5.