What is the treatment for ascending lymphangitis caused by a cat bite?

Treatment for Ascending Lymphangitis from Cat Bite

For ascending lymphangitis caused by a cat bite, amoxicillin-clavulanate (500/875 mg twice daily orally) is the recommended first-line treatment due to its excellent coverage against Pasteurella multocida and other common pathogens in cat bite infections. 1

Microbiology and Pathophysiology

• Cat bites have a high risk of infection with a polymicrobial profile, with Pasteurella multocida present in 75% of cases, which is often the causative organism in ascending lymphangitis 1
• Cat bite infections typically contain mixed aerobic and anaerobic bacteria, with an average of 5 different bacterial isolates per wound 1
• Staphylococci and streptococci are found in approximately 40% of cat bite wounds and can contribute to lymphangitis 1
• Cat bites have a greater prevalence of anaerobes (65%) compared to dog bites (50%) 1

Treatment Algorithm

Outpatient Management (Mild to Moderate Lymphangitis)

• First-line therapy: Amoxicillin-clavulanate 500/875 mg orally twice daily for 7-10 days 1
• Alternative options (if penicillin allergic):
  • Doxycycline 100 mg orally twice daily (excellent activity against P. multocida) 1
  • Fluoroquinolones (ciprofloxacin 500-750 mg twice daily, moxifloxacin 400 mg daily) plus metronidazole for anaerobic coverage 1

Inpatient Management (Severe Lymphangitis)

• First-line IV therapy: Ampicillin-sulbactam 1.5-3.0 g IV every 6-8 hours 1
• Alternative IV options:
  • Piperacillin-tazobactam 3.37 g IV every 6-8 hours 1
  • Carbapenems (ertapenem 1 g daily, imipenem 1 g every 6-8 hours, or meropenem 1 g every 8 hours) 1
  • Second-generation cephalosporins such as cefoxitin 1 g IV every 6-8 hours 1

Important Considerations and Pitfalls

• Avoid these antibiotics as they have poor activity against P. multocida:

  • First-generation cephalosporins (cephalexin)
  • Dicloxacillin
  • Macrolides (erythromycin)
  • Clindamycin alone (without additional coverage) 1

• Adjunctive measures are critical to successful treatment:

  • Thorough wound cleansing with sterile normal saline 1
  • Elevation of the affected limb to reduce swelling 1
  • Surgical drainage if abscess formation is present 2

• Monitor for complications:

  • Septic arthritis, osteomyelitis, and tendonitis may require extended antibiotic courses (4-6 weeks) 1
  • Hand wounds are particularly prone to complications and should be monitored closely 1, 2
  • Patients with immunocompromise or underlying hepatic disease are at higher risk for severe infection 1

• Transition from IV to oral therapy can be considered when clinical improvement is observed, typically after 24-48 hours of IV antibiotics 1

Special Situations

• For patients with suspected Bartonella henselae infection (cat scratch disease), azithromycin may be beneficial (500 mg on day 1, then 250 mg for 4 additional days) 3, 4
• In elderly patients or those with comorbidities, consider lower threshold for hospitalization and IV antibiotics due to higher risk of complications including sepsis 5