Erysipelothrix rhusiopathiae is a zoonotic Gram-positive bacillus transmitted from animals to humans.
It is an occupational hazard for those handling meat, fish, or animals (e.g. butchers, abattoir workers, farmers, vets).
Infections are usually cutaneous but can occasionally become systemic.

🔬 Characteristics

Slender, Gram-positive, non-motile, non-spore-forming bacillus.
Facultative anaerobe, catalase-negative.
Distinguished from other Gram-positive rods (e.g. Listeria) by lack of motility.

🌍 Source

Found in the tonsils and intestines of livestock, particularly pigs 🐖, but also in turkeys, fish 🐟, and other animals.
Humans acquire infection via skin abrasions when handling infected animals, raw meat, or fish.
Considered an occupational zoonosis in the UK meat and fishing industries.

🩺 Pathogenicity

Erysipeloid (cutaneous disease): Most common form. Localised, painful, violaceous, raised skin lesion (often on the hands or fingers). May resemble cellulitis but typically non-suppurative.
Systemic infection: Rare but may cause sepsis, arthritis, and endocarditis, which can be aggressive and destructive.
More severe disease seen in immunocompromised patients or those with occupational re-exposure.

🧪 Investigations

Diagnosis usually clinical in typical cutaneous erysipeloid.
Culture can be performed from lesion swabs, blood (if systemic), or joint fluid.
Gram stain: Gram-positive slender rods.
Important to differentiate from streptococcal cellulitis and erysipelas.

💊 Sensitivities

Highly sensitive to Penicillin (first-line).
Alternatives in penicillin allergy: Cephalosporins, Clindamycin, or Fluoroquinolones.
❌ Naturally resistant to Vancomycin, which is unusual among Gram-positive bacteria (good exam pearl).

🛠️ Management

Cutaneous disease: Oral Penicillin or Amoxicillin is usually curative.
Severe/systemic infection: IV Penicillin, often prolonged if endocarditis is present.
Supportive care for pain and secondary complications.
Prevention: Use gloves and protective equipment when handling meat, fish, or animals. Education in at-risk occupations is key.

📌 Key Exam Pearls

“Fish handler’s disease” or “Butcher’s cellulitis” are old names for erysipeloid.
Differentiate from Streptococcus pyogenes erysipelas: erysipeloid is localised, violaceous, and painful but not purulent or spreading.
Systemic involvement → Endocarditis is the most serious complication.
Vancomycin resistance is a favourite MCQ point – unusual among Gram-positive organisms.

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Erysipelothrix rhusiopathiae

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