Treatment of Pasteurella Infections
Penicillin or amoxicillin is the first-line treatment for Pasteurella infections, with doxycycline being the preferred alternative for penicillin-allergic patients. 1, 2, 3
First-Line Treatment Options
Penicillin-Based Therapy
- Penicillin: 500 mg four times daily orally 1
- Amoxicillin: 500 mg three times daily orally 1
- Amoxicillin-clavulanate: 875/125 mg twice daily orally (provides broader coverage for polymicrobial infections) 1
- Ampicillin-sulbactam: 1.5-3.0 g every 6-8 hours IV (for severe infections) 1
Alternative for Penicillin-Allergic Patients
- Doxycycline: 100 mg twice daily orally 1, 2
- Excellent activity against Pasteurella multocida
- FDA-approved for tularemia and plague (both caused by Pasteurella species) 2
Treatment Algorithm
For mild to moderate infections (localized cellulitis):
- First-line: Oral penicillin (500 mg QID) or amoxicillin (500 mg TID)
- If penicillin-allergic: Doxycycline 100 mg BID
For moderate to severe infections (extensive cellulitis, systemic symptoms):
- First-line: Amoxicillin-clavulanate 875/125 mg BID
- If penicillin-allergic: Doxycycline 100 mg BID or fluoroquinolone (moxifloxacin 400 mg daily)
For severe infections requiring hospitalization:
- Ampicillin-sulbactam 1.5-3.0 g IV every 6 hours
- If penicillin-allergic: IV fluoroquinolone or combination therapy with clindamycin plus trimethoprim-sulfamethoxazole
Duration of Therapy
- Uncomplicated soft tissue infections: 5-7 days
- Deep tissue infections or bacteremia: 10-14 days
- Osteomyelitis or joint infections: 4-6 weeks
Additional Considerations
Wound Management
- Irrigation and debridement of necrotic tissue are crucial components of treatment 1
- Surgical exploration may be necessary for deep wounds to remove foreign bodies
Common Clinical Presentations
- Rapidly developing cellulitis at the site of animal bite (especially cat or dog) 4
- Serosanguineous or purulent drainage from wounds 4
- Can progress to deeper infections including osteomyelitis if untreated 4
Special Populations
- Immunocompromised patients: Consider broader empiric coverage and longer treatment duration
- Patients with prosthetic joints or valves: Consider longer treatment and infectious disease consultation
Other Effective Antibiotics
If first-line agents cannot be used, the following alternatives have demonstrated in vitro activity against Pasteurella:
- Fluoroquinolones: Ciprofloxacin 500-750 mg twice daily or moxifloxacin 400 mg daily 1, 5
- Trimethoprim-sulfamethoxazole: 160/800 mg twice daily 1, 5
- Second-generation cephalosporins: Cefuroxime 500 mg twice daily 1, 3
- Third-generation cephalosporins: Ceftriaxone 1 g every 12-24 hours IV 1
Pitfalls and Caveats
- Macrolides (erythromycin, clarithromycin) have variable activity against Pasteurella and should not be first-line therapy 3, 5
- Clindamycin alone is not recommended as it has poor activity against Pasteurella multocida 1
- Delay in treatment can lead to serious complications including osteomyelitis, septic arthritis, or bacteremia 4, 6
- Always consider polymicrobial infection in animal bite wounds; amoxicillin-clavulanate provides broader coverage 1
Monitoring and Follow-up
- Clinical improvement should be evident within 48-72 hours
- If no improvement, consider:
- Surgical debridement
- Change in antibiotic therapy
- Presence of deeper infection requiring imaging studies
- Possibility of resistant organisms
Pasteurella infections typically respond well to appropriate antibiotic therapy when initiated promptly, with penicillin derivatives being highly effective first-line agents 7, 4.