Which organism causes erysipeloid with marginating plaques after handling fish?

• A. Vibrio vulnificus
• B. Streptococcus pyogenes
• C. Staphylococcus aureus
• D. Erysipelothrix rhusiopathiae

Answer: (D)

Erysipelothrix rhusiopathiae is the classic cause of erysipeloid, a localized skin infection that follows handling of fish or other animals. The organism enters through tiny skin breaks and produces a violaceous, swollen plaque on the hands with sharp, raised margins that often spread along lymphatics—hence the marginating appearance. This occupational exposure pattern—fish handlers, meat workers, veterinarians—helps distinguish it from other skin infections. Vibrio vulnificus can cause severe cellulitis after seawater or raw seafood exposure and is typically more rapidly progressive, especially in people with liver disease; Streptococcus pyogenes and Staphylococcus aureus cause erysipelas or cellulitis but lack the characteristic fish-handling association and marginating plaque of erysipeloid. Penicillin is the usual treatment.