Erysipelothrix rhusiopathiae

MICROBIOLOGY

• Aerobe or facultative anaerobe, thin, pleomorphic Gram-positive rod.
• Zoonotic infection more commonly infects turkeys, pigs and other animals than humans.
• E. rhusiopathiae is the only genus within the species that infects humans.
• Culture isolation is difficult.
  • A slow grower in enriched blood media with 5-10% CO₂.
• Intrinsically resistant to vancomycin, which commonly might be used empirically unless the organism is appropriately identified and distinguished from diphtheroids (Corynebacterium spp.) and Lactobacillus.
  • The lab can confuse with diphtheroids and coryneforms, but E. rhusiopathiae is distinguished by H₂S production.
  • Also usually resistant to aminoglycosides and sulfonamides.