Pasteurella multocida Infection
Skin infection with Pasteurella multocida is one of the most dangerous and fastest-spreading acute bacterial infections linked to bites, scratches or small wounds exposed to animal saliva, especially from cats and dogs. A facultatively anaerobic gram-negative coccobacillus, Pasteurella multocida carries a potent tissue-destroying toxin and multiplies extremely quickly, causing extensive cellulitis within hours of entering the skin. Without prompt diagnosis and correctly targeted antibiotics, the infection can rapidly progress to suppurative tenosynovitis, septic arthritis, osteomyelitis or life-threatening sepsis.
At Haute-Derma, we manage Pasteurella multocida infection with urgent surgical wound care, antibiotics with specific activity against this gram-negative organism, and regenerative therapies to prevent poor scarring after the infection.
Pathogenesis and Behavior of Pasteurella multocida
Source of Infection and Microbiology
- Animal oral flora: Pasteurella multocida normally lives in the mouth and upper airways of cats (70–90%) and dogs (50–60%).
- How cat teeth penetrate: Cat teeth are thin and needle-sharp, so a bite easily punches through the skin and dermis down to tendon sheaths, the periosteum and the deep spaces of the hand. This creates an ideal low-oxygen environment for the bacteria to grow.
Virulence Factors and Tissue Damage
- Pasteurella multocida dermonecrotic toxin (PMT): Activates intracellular G-protein signaling, driving abnormal cell proliferation, stimulating bone resorption by osteoclasts and causing necrosis of the surrounding soft tissue.
- Polysaccharide (hyaluronic acid) capsule: Helps the bacteria evade phagocytosis by neutrophils, allowing very rapid multiplication in the tissue spaces.
- Lipopolysaccharide (LPS) endotoxin: Triggers a flood of inflammatory cytokines (TNF-alpha, IL-1, IL-6), leading to marked vessel dilation, leaky capillaries and acute swelling.
Clinical Presentations of Pasteurella multocida Infection
Rapidly Progressive Cellulitis
- Very short incubation: This is the single most useful clinical clue. Inflammation appears very quickly, usually 2–24 hours after the bite (about 12 hours on average), much sooner than with staphylococcal or streptococcal infections.
- Local signs: The skin around the bite quickly becomes very swollen, red, hot and intensely painful, with pain out of proportion to the visible wound. The redness spreads hour by hour.
Discharge and Tissue Necrosis
- The wound oozes blood-stained serous fluid or cloudy gray pus with a typical foul smell.
- Blisters, hemorrhagic bullae and gray-black necrotic crusts form around the puncture site.
Deep Hand and Systemic Complications
- Necrotizing tenosynovitis and septic arthritis: When the bite is on the hand or wrist, bacteria spread along the flexor tendon sheaths, causing compartment syndrome, joint stiffness and a risk of permanent finger disability.
- High fever, shaking chills and tender swollen regional lymph nodes (for example in the armpit or groin). In people with weakened immunity, the infection can progress to sepsis, meningitis or endocarditis.
Telling Pasteurella Infection Apart From Other Bite Infections
| Pasteurellosis (Pasteurella multocida) | Staphylococcus / Streptococcus | Cat Scratch Disease (Bartonella henselae) |
|---|---|---|
| Cat and dog bites or scratches | Bacteria from the person's own skin | Cat scratches or cat fleas |
| Very rapid (2–24 hours) | Slower (24–72 hours) | Subacute (1–3 weeks) |
| Fast-spreading redness and swelling, foul discharge | Redness, swelling, abscess with yellow pus | Small papule that becomes pustular, then crusts |
| Tenosynovitis, tissue necrosis | Skin abscess, cellulitis | Prolonged regional lymph node swelling |
Initial Assessment and Surgical Wound Care at Haute-Derma
High-Pressure Irrigation and Wound Antisepsis
- As soon as the patient arrives, the wound is irrigated under pressure with a large volume of 0.9% saline to remove as many bacteria and as much animal saliva as possible.
- The wound is then disinfected with 1% povidone-iodine or 0.2% chlorhexidine.
Surgical Debridement
- Under local anesthesia, we check the depth of the bite, particularly puncture wounds on the hand and over joint creases.
- Dead and crushed tissue is debrided.
- Deep cat-bite punctures and wounds presenting more than 12 hours after the bite should not be closed primarily, because sealing them creates a low-oxygen pocket where bacteria can flourish.
Medical Treatment and Recovery Care at Haute-Derma
Targeted Antibiotic Regimens
- First-line options:
- Amoxicillin-clavulanate 875/125 mg by mouth twice daily for 7–10 days for mild to moderate infection.
- Ampicillin-sulbactam 1.5–3 g intravenously every 6 hours for severe infection or deep complications.
- Options for patients allergic to penicillin:
- Doxycycline 100 mg by mouth twice daily.
- Or a fluoroquinolone (ciprofloxacin 500 mg twice daily or levofloxacin 500 mg once daily) combined with metronidazole 500 mg three times daily to cover anaerobes.
- Important warning: Pasteurella multocida is intrinsically resistant or responds very poorly to common antibiotics such as first-generation cephalosporins (cephalexin), clindamycin on its own, and macrolides (erythromycin). Never treat a cat bite with cephalexin on your own.
Vaccination and Supportive Care
- Tetanus: Vaccination history must always be checked, with tetanus vaccine and/or tetanus antitoxin (SAT) given as indicated.
- Rabies: The biting animal's status is assessed so that rabies vaccination can be given according to guidelines.
- Pain relief and swelling control: NSAIDs (ibuprofen 400 mg) and elevation of the affected limb to help venous drainage.
Skin Repair and Scar Prevention After Inflammation
- Once the infection is fully controlled, repair creams containing madecassoside, panthenol and epidermal growth factor (EGF) help regenerate the epidermis.
- Long-pulse or fractional laser, combined with topical niacinamide and azelaic acid, fades post-inflammatory hyperpigmentation and helps prevent tight, contracting scars.
