What is the recommended treatment for Pasteurella infections?

Treatment of Pasteurella Infections

For Pasteurella infections, amoxicillin-clavulanate 875/125 mg twice daily orally is the recommended first-line treatment, with penicillin or amoxicillin as highly effective alternatives for penicillin-susceptible patients. 1

First-Line Antibiotic Therapy

For Penicillin-Tolerant Patients

• Amoxicillin-clavulanate 875/125 mg orally twice daily is the preferred agent for animal bite wounds where Pasteurella is suspected or confirmed 1
• Penicillin 500 mg four times daily or amoxicillin 500 mg three times daily for 7-10 days are excellent alternatives with high efficacy 1, 2, 3
• Penicillin remains the drug of choice for confirmed Pasteurella infections due to excellent activity and decades of clinical success 2, 3

Intravenous Options for Severe Infections

• Ampicillin-sulbactam 1.5-3.0 g every 6-8 hours IV for hospitalized patients 1
• Piperacillin-tazobactam 3.37 g every 6-8 hours IV provides broader coverage 1
• Carbapenems (ertapenem, imipenem, meropenem) are effective but should be reserved for complicated cases 1

Alternative Agents for Penicillin-Allergic Patients

Highly Effective Alternatives

• Doxycycline 100 mg twice daily has excellent activity against Pasteurella multocida and is FDA-approved for tularemia caused by Francisella tularensis (formerly Pasteurella tularensis) 1, 4, 3
• Fluoroquinolones demonstrate excellent in vitro activity 1:
  • Ciprofloxacin 500-750 mg twice daily orally or 400 mg every 12 hours IV
  • Levofloxacin 750 mg daily
  • Moxifloxacin 400 mg daily (provides anaerobic coverage as monotherapy)

Second-Generation Cephalosporins

• Cefuroxime 500 mg twice daily orally or 1 g every 12 hours IV has good activity against P. multocida but misses anaerobes 1
• Cefoxitin 1 g every 6-8 hours IV provides anaerobic coverage 1

Third-Generation Cephalosporins

• Ceftriaxone 1 g every 12 hours IV 1
• Cefotaxime 1-2 g every 6-8 hours IV 1
• These agents have good P. multocida activity but limited anaerobic coverage 1

Other Options

• Trimethoprim-sulfamethoxazole 160-800 mg twice daily has good aerobic activity but poor anaerobic coverage 1, 5

Critical Pitfalls to Avoid

Antibiotics with Poor Pasteurella Activity

Avoid these agents as monotherapy for Pasteurella infections:

• Clindamycin misses P. multocida despite good activity against staphylococci, streptococci, and anaerobes 1
• First-generation cephalosporins (cephalexin, cefazolin) have poor P. multocida activity 1
• Dicloxacillin lacks adequate Pasteurella coverage 1
• Erythromycin and macrolides (clarithromycin, azithromycin) show only intermediate susceptibility 6, 5

When Combination Therapy is Needed

If using agents with gaps in coverage, combine appropriately 1:

• Clindamycin 300 mg three times daily PLUS a fluoroquinolone for penicillin-allergic patients
• Metronidazole 250-500 mg three times daily (for anaerobes) PLUS ciprofloxacin or levofloxacin (for aerobes including Pasteurella)

Clinical Context and Duration

Typical Presentation

• Rapidly developing cellulitis within 12-24 hours after cat or dog bite (especially cat bites in 72% of cases) 2
• Serosanguineous or purulent drainage with lymphangitis 2
• Most commonly affects hands after deep penetrating wounds 2

Treatment Duration

• 7-10 days for uncomplicated soft tissue infections 1
• Longer courses for complicated infections, osteomyelitis, or respiratory involvement 2, 3

Special Populations

• Elderly patients with chronic lung disease (COPD, bronchiectasis) are at higher risk for Pasteurella pneumonia after inhalation exposure 3
• Immunocompromised patients require more aggressive therapy 1

Adjunctive Management

Wound Care

• Immediate surgical drainage is essential for purulent collections 2
• Primary wound closure is NOT recommended except for facial wounds, which require copious irrigation, cautious debridement, and preemptive antibiotics 1

Tetanus Prophylaxis

• Administer tetanus toxoid if not vaccinated within 10 years 1
• Tdap is preferred over Td if not previously given 1

Microbiological Considerations

• Beta-lactamase production by Pasteurella is rare; no beta-lactamase producing isolates were found in recent surveillance studies 6
• Animal bite wounds are polymicrobial, averaging 5 different aerobic and anaerobic bacteria including Staphylococcus aureus, Bacteroides, Fusobacterium, and Porphyromonas species 1
• Culture and susceptibility testing should guide therapy when initial empiric treatment fails 1