Skip to content
MicrobioHub
Back to database
Bacilos Gram-positivos

Erysipelothrix rhusiopathiae

Thin Gram-positive bacilli, sometimes filamentous

Identification & Growth

Identification

  • Catalase-negative, H₂S-positive on TSI — an almost unique combination

Growth Conditions

  • Blood agar, 35 °C, 24–48 h, faint alpha-hemolysis

Clinical Significance

  • Erysipeloid in butchers, veterinarians and fish handlers; endocarditis

Intrinsic Resistance

  • Intrinsic resistance to vancomycin, aminoglycosides and sulfonamides

Bench Alerts

  • Never treat empirically with vancomycin — penicillin is the drug of choice
  • Do not confuse with Listeria (catalase-positive and motile)

Clinical Notes

Clinical presentations

  • Causes erysipeloid, a localized, painful, violaceous skin lesion on the hands following occupational exposure.
  • Can cause systemic bacteremia with endocarditis in disseminated cases.
  • Rarely causes septic arthritis and diffuse skin infection.

Specimens and collection

  • Skin biopsy at the lesion margin has higher diagnostic yield than aspirate from the lesion center.
  • Blood cultures are indicated in suspected generalized form or endocarditis.
  • Occupational history (handling fish, pork, or poultry) should be included on the requisition to guide clinical suspicion.

Epidemiology and at-risk populations

  • Zoonosis associated with handling fish, pork, poultry, and animal products.
  • At-risk occupations include fishermen, butchers, veterinarians, and abattoir workers.
  • Systemic form is more common in immunocompromised patients or those with alcohol use disorder.

Resistance and therapeutic implications

  • Exhibits intrinsic resistance to vancomycin, unlike most Gram-positive bacilli.
  • Penicillin is the treatment of choice, retaining excellent activity against this organism.
  • Fluoroquinolones and third-generation cephalosporins are effective alternatives.

Bench and reporting notes

  • Thin, non-spore-forming, catalase-negative Gram-positive rod that can resemble Listeria on Gram stain.
  • H2S production in triple sugar iron agar aids differentiation from Listeria monocytogenes.
  • Intrinsic vancomycin resistance should be explicitly flagged in the report to avoid inappropriate empiric therapy.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Erysipelothrix rhusiopathiae in the lab?

Erysipelothrix rhusiopathiae is identified through catalase-negative, h₂s-positive on tsi — an almost unique combination.

What are the intrinsic resistances of Erysipelothrix rhusiopathiae?

This organism is naturally resistant to intrinsic resistance to vancomycin, aminoglycosides and sulfonamides. These drugs should not be reported as susceptible.

Where is Erysipelothrix rhusiopathiae commonly found?

It is typically associated with erysipeloid in butchers, veterinarians and fish handlers; endocarditis.

Antibiogram InterpreterCheck BrCAST 2026 breakpointsRugai InterpreterBiochemical identification tools

Want the free Bench Kit?

Sign up to receive the PDF kit: agars, Gram, Rugai, dilutions and the antibiogram checklist.