What is the recommended treatment for cat bite cellulitis?

Management of Cat Bite Cellulitis

For cat bite cellulitis, amoxicillin-clavulanate (875/125 mg twice daily) is the recommended first-line treatment due to its excellent coverage against Pasteurella multocida and other common pathogens found in cat bite wounds. 1

Microbiology and Pathophysiology

Cat bites frequently cause cellulitis due to the unique characteristics of feline dentition:

• Deep puncture wounds that can inoculate bacteria into tissues
• Common pathogens include:
  • Pasteurella multocida (isolated in >50% of cat bite wounds)
  • Streptococcus species
  • Staphylococcus species
  • Anaerobes (including Bacteroides species)

Cat bites have a higher infection rate than dog bites, with hand injuries being particularly prone to infection due to proximity to joints and tendons.

Treatment Algorithm

First-line Antibiotic Therapy:

• Oral therapy (for mild to moderate infections):
  • Amoxicillin-clavulanate 875/125 mg twice daily 1
  • Duration: 5-7 days for uncomplicated infections, 10-14 days for more severe cases

Alternative Oral Options (for penicillin-allergic patients):

• Doxycycline 100 mg twice daily (excellent activity against P. multocida) 1
• Moxifloxacin 400 mg daily (good monotherapy with anaerobic coverage) 1
• Clindamycin 300-450 mg three times daily PLUS a fluoroquinolone (for P. multocida coverage) 1

Parenteral Therapy (for severe infections):

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours 1
• Piperacillin-tazobactam 3.37 g every 6-8 hours 1
• Carbapenems (for severe infections with resistant organisms) 1

Management Approach

1. Wound Care:

   • Thorough irrigation with sterile saline
   • Debridement of devitalized tissue
   • Leave puncture wounds open to heal by secondary intention
   • Elevation of affected area to reduce edema 1

2. Antibiotic Timing:

   • Start antibiotics immediately after wound care
   • Early antibiotic therapy is crucial for preventing serious complications 2, 3

3. Monitoring and Follow-up:

   • Re-evaluate within 24-48 hours
   • Watch for signs of worsening infection (increasing erythema, pain, swelling, fever)
   • Consider imaging (ultrasound, CT, MRI) if deep space infection or osteomyelitis is suspected

4. Indications for Hospitalization:

   • Systemic symptoms (fever, chills)
   • Rapidly spreading cellulitis
   • Hand infections (especially over joints or tendon sheaths)
   • Immunocompromised patients
   • Failed outpatient therapy

Special Considerations

• Hand Injuries: Have higher risk of complications and may require surgical consultation
• Immunocompromised Patients: Consider broader spectrum antibiotics and lower threshold for admission
• Deep Structure Involvement: Suspect if pain is disproportionate to visible signs or if symptoms persist despite appropriate antibiotics

Common Pitfalls to Avoid

1. Using inappropriate antibiotics: Standard anti-staphylococcal antibiotics like dicloxacillin or cephalexin alone are inadequate for cat bites due to poor coverage of P. multocida 1, 4

2. Delayed treatment: Cat bite infections can progress rapidly; early antibiotic therapy significantly reduces infection rates 5

3. Inadequate follow-up: Cat bite wounds can develop delayed infections or deep space infections even after initial improvement

4. Missing deep structure involvement: Tendons, joints, and bones can become infected even with seemingly minor wounds, particularly in hand injuries

5. Premature wound closure: Primary closure of puncture wounds can increase infection risk by creating an anaerobic environment

Remember that cat bite cellulitis can progress rapidly to serious infections including bacteremia and sepsis, as documented in case reports 6. Prompt and appropriate antibiotic therapy targeting the likely pathogens is essential for preventing these complications.