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Feline Bite Infection (Pasteurella) – A Complete Guide

Overview

A feline bite infection caused by Pasteurella bacteria is a common, potentially serious complication of cat scratches or bites. The genus Pasteurella—most often Pasteurella multocida—normally inhabits the mouths of healthy cats and dogs. When a cat’s sharp teeth breach the skin, the bacteria are inoculated directly into deeper tissues, leading to rapid infection.

Who it affects: Anyone who owns or handles cats can be exposed, but the risk is higher for:

• Children (who may not realize the force of a bite)
• People with weakened immune systems (e.g., HIV, chemotherapy, diabetes, chronic steroid use)
• Individuals with poor peripheral circulation or peripheral neuropathy

Prevalence: In the United States, cat bites account for CDC-reported animal bite injuries about 1.5–2.5 per 1,000 people annually, and Pasteurlla is isolated in up to 90 % of cultured cat‑bite wound specimens (Mayo Clinic Proceedings, 2007). Prompt treatment dramatically reduces the chance of severe complications.

Symptoms

Symptoms usually appear within a few hours to 48 hours after the bite.

• Redness and swelling – localized to the bite site, may spread to surrounding tissue.
• Pain or throbbing sensation – often disproportionate to the size of the wound.
• Warmth – the area feels hot to the touch.
• Pus or drainage – yellow‑white fluid may ooze from the wound.
• Fever – low‑grade (≤38.5 °C / 101.3 °F) in mild cases, higher in severe infections.
• Swollen lymph nodes – especially in the neck or axillae, depending on bite location.
• Limited range of motion – if the bite is near a joint, movement may become painful.
• Systemic signs – chills, headache, malaise, or nausea, indicating spread.
• Skin ulceration or necrosis – rare, but may develop if infection progresses without treatment.

Causes and Risk Factors

What causes a Pasteurella infection?

Pasteurella spp. are gram‑negative, facultatively anaerobic coccobacilli. Cats carry them as part of their normal oral flora. When a cat’s teeth puncture the skin, the bacteria bypass the protective barrier and multiply rapidly, producing toxins that trigger inflammation.

Key risk factors

• Deep puncture wounds – cat teeth create narrow, deep channels that are hard to clean.
• Multiple bites or scratches – increases bacterial load.
• Delayed wound care – washing, debridement, or early antibiotics not performed.
• Immunocompromise – reduced ability to fight infection.
• Existing skin conditions – eczema, psoriasis, or cuts at the bite site.
• Alcohol or drug use – may impair judgment, leading to more severe injuries.

Diagnosis

Clinical suspicion is usually enough to start treatment, but confirmatory tests help tailor therapy.

Physical examination

• Assess wound depth, presence of foreign material (cat hair, debris), and signs of cellulitis.
• Check for lymphadenopathy and range of motion.

Laboratory tests

• Wound culture and sensitivity – a sterile swab or tissue sample is sent to the lab. Pasteurella grows within 24–48 hours.
• Complete blood count (CBC) – may reveal leukocytosis (elevated white blood cells).
• C‑reactive protein (CRP) or erythrocyte sedimentation rate (ESR) – markers of inflammation.
• Blood cultures – indicated if fever >38.5 °C or signs of systemic infection.

Imaging (when needed)

• Ultrasound – evaluates for abscess formation.
• X‑ray or MRI – if there is concern for bone involvement (osteomyelitis) or deep‑space infection.

Treatment Options

Management combines prompt antimicrobial therapy, wound care, and, when necessary, surgical intervention.

Antibiotic therapy

Pasteurella is typically sensitive to several classes of antibiotics. Choice depends on allergy profile, severity, and local resistance patterns.

• First‑line oral agents (for uncomplicated bites):
  • Amoxicillin‑clavulanate 875 mg/125 mg PO twice daily for 5–7 days (or 10–14 days for deeper wounds).
  • Alternatives (if β‑lactam allergic): doxycycline 100 mg PO twice daily or a fluoroquinolone such as levofloxacin 500 mg PO daily.
• Intravenous options (for severe cellulitis, abscess, or immunocompromised patients):
  • Ceftriaxone 1–2 g IV daily + metronidazole 500 mg IV q8h.
  • Meropenem 1 g IV q8h (covers broader gram‑negative spectrum).
• Duration: 5–7 days for superficial infections; 10–14 days for deeper or joint involvement.

Wound care

• Immediate irrigation with copious sterile saline (≥50 mL per cm of wound).
• Removal of devitalized tissue (debridement) in the office or operating room.
• Leave the wound open or loosely loosely closed; apply a sterile dressing changed daily.

Surgical intervention

• Incision and drainage (I&D) for abscesses.
• Joint aspiration or arthrotomy if the bite penetrates a joint.
• Consult orthopedics or plastic surgery for complex facial or hand injuries.

Supportive measures

• Analgesics – acetaminophen or ibuprofen for pain and inflammation.
• Elevation of the affected limb to reduce edema.
• Tetanus prophylaxis if immunization status is uncertain (Tdap booster within 5 years).

Living with Feline Bite Infection (Pasteurella)

Even after the acute phase, some patients need ongoing care.

Activity modifications

• Avoid heavy lifting or strenuous use of the affected hand/arm for at least 1 week.
• Keep the wound clean and dry; use waterproof dressings during bathing.

Monitoring

• Check the wound daily for increased redness, swelling, or drainage.
• Record temperature twice daily for the first 48 hours after starting antibiotics.

Nutrition & immunity

• Consume protein‑rich foods (lean meats, legumes) to support tissue repair.
• Stay hydrated; aim for at least 2 L of water per day.
• Consider a daily multivitamin with zinc and vitamin C if dietary intake is insufficient.

Follow‑up

• Schedule a return visit with your primary care provider or wound clinic 3–5 days after starting antibiotics.
• Longer follow‑up (2–4 weeks) is advised for deep‑tissue or joint involvement.

Prevention

Most cat‑bite infections are preventable with proper handling and early wound care.

• Know cat behavior – avoid provoking a cat that is hissing, swatting, or showing flattened ears.
• Use protective gloves when handling unfamiliar or stressed cats, especially in veterinary or animal‑control settings.
• Immediate wound care – wash any bite or scratch with soap and running water for at least 15 minutes.
• Early medical evaluation – seek care within 12 hours if the bite is deep, bleeding heavily, or located on the face, hand, or near a joint.
• Keep tetanus immunizations up to date (booster every 10 years).
• For immunocompromised individuals, discuss with a physician whether prophylactic antibiotics are warranted after any cat bite.

Complications

If left untreated or inadequately treated, Pasteurella infections can lead to serious sequelae:

• Cellulitis – spreading skin infection that may require IV antibiotics.
• Abscess formation – collection of pus that often needs surgical drainage.
• Septic arthritis – infection of a joint, causing permanent cartilage damage if not promptly addressed.
• Osteomyelitis – bone infection, especially common with bites over the clavicle, ulna, or mandible.
• Necrotizing fasciitis – rare, rapidly progressive tissue death; a surgical emergency.
• Bacteremia and sepsis – systemic spread can affect heart valves (endocarditis) or cause multi‑organ failure.
• Scarring or functional impairment – especially in hand or facial bites, leading to reduced range of motion or cosmetic concerns.

When to Seek Emergency Care

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Sources: Mayo Clinic, CDC, NIH National Institute of Allergy and Infectious Diseases, WHO, Cleveland Clinic, Journal of Infectious Diseases 2020; Clinical Microbiology Reviews 2018.

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