[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/) › Erysipelothrix rhusiopathiae

# Erysipelothrix rhusiopathiae

- Bacterium

## Gram-positive?

Thick peptidoglycan wall: stains purple.

- Exam priority: medium

A bacterium from pigs and fish that causes a purple, burning skin infection on the hands of people who handle fish or raw meat.

Updated Nov 13, 2026

Also called: erysipeloid agent, swine erysipelas bacterium

## Quick facts

**Type**
Bacterium · [Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

**Gram / shape**
Gram-positive · Thin rod that may form long filaments

**Spread**
Occupational · Occasionally cat or dog bites

**Causes**
Erysipeloid · Diffuse cutaneous erysipeloid

**Treatment**
Penicillin is the drug of choice

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Fish handler or butcher with a violet, burning plaque on the hand: erysipeloid (Erysipelothrix).
- Gram-positive rod that makes H2S on triple sugar iron agar.
- Intrinsically resistant to vancomycin: identify it fast in Gram-positive rod endocarditis.
- Penicillin is the drug of choice.

## At a glance

**Gram**
Gram-positive

**Shape**
Thin rod that may form long filaments

**Oxygen**
Facultative anaerobe

**Family**
Erysipelotrichaceae

## Morphology

- Non-spore-forming, non-motile Gram-positive rod
- Catalase-negative and alpha-haemolytic on blood agar
- Produces hydrogen sulfide on triple sugar iron agar, unusual for a Gram-positive rod

## Transmission

- Scratches or punctures while handling fish, shellfish, raw pork or poultry
- Occupational: fishers, fishmongers, butchers, slaughterhouse workers and veterinarians
- Occasionally cat or dog bites
- Not spread from person to person

**Reservoir:** Pigs (swine erysipelas), fish slime, shellfish, poultry; it survives in soil and water

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- A capsule that resists phagocytosis
- Neuraminidase and hyaluronidase that help it spread in tissue
- Strong tendency to reach heart valves once in the blood

## Diseases it causes

- Erysipeloid: localised cellulitis of the finger or hand [Hand infections (paronychia, felon, flexor tenosynovitis) →](https://durgical.com/en/conditions/hand-infections/)
- Diffuse cutaneous erysipeloid with spreading lesions (rare)
- Bacteraemia with infective endocarditis, mostly of the aortic valve [Infective endocarditis →](https://durgical.com/en/conditions/infective-endocarditis/)
- Septic arthritis [Septic Arthritis of the Knee →](https://durgical.com/en/conditions/septic-arthritis-of-the-knee/)

## Clinical picture

- Within a week of the injury: a raised, violet, sharply bordered plaque on the hand that burns or itches
- The edge spreads slowly while the centre clears; little pus and usually no fever
- Endocarditis often affects native valves, needs surgery often and is linked to alcohol use

## Diagnosis

- Occupational history: fish, meat or animal contact
- Full-thickness skin biopsy of the lesion edge for culture or PCR (the bacteria lie deep in the skin)
- Blood cultures if systemic illness; echocardiography if bacteraemic
- May be misidentified as lactobacilli or enterococci

## Treatment

Penicillin is the drug of choice; cephalosporins, fluoroquinolones and clindamycin are alternatives. It is intrinsically resistant to vancomycin (and to aminoglycosides and sulfonamides), so empirical vancomycin for Gram-positive rod endocarditis fails.

Drug class only; doses and regimens are set by the clinician from the current guideline.

In Pharmacology:

- [Benzylpenicillin (penicillin G)](https://durgical.com/en/pharmacology/benzylpenicillin/)
- [Phenoxymethylpenicillin (penicillin V)](https://durgical.com/en/pharmacology/phenoxymethylpenicillin/)
- [Ceftriaxone](https://durgical.com/en/pharmacology/ceftriaxone/)
- [Ciprofloxacin](https://durgical.com/en/pharmacology/ciprofloxacin/)
- [Clindamycin](https://durgical.com/en/pharmacology/clindamycin/)

## Prevention

- Gloves and protection of hand wounds when handling fish, shellfish and raw meat
- Vaccination of pigs is a veterinary measure that reduces the reservoir

## Memory aid

The «purple hand of the fish market»: a violet ring that creeps out from the finger, and a bug that laughs at vancomycin.

## Test yourself

Think of the answer, then tap the question to see it.

## Which occupations are at risk of erysipeloid?

Those handling fish, shellfish, raw pork or poultry: fishers, fishmongers, butchers and slaughterhouse workers.

## Why is it dangerous to treat Erysipelothrix endocarditis empirically with vancomycin?

The organism is intrinsically resistant to vancomycin.

## Which biochemical clue is unusual for this Gram-positive rod?

It produces hydrogen sulfide on triple sugar iron agar.

## Which sample gives the best yield in erysipeloid?

A full-thickness skin biopsy of the advancing edge, because the bacteria lie deep in the skin.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/microbiology/erysipelothrix-rhusiopathiae/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

## Connections

## Related 4

- [Listeria monocytogenes](https://durgical.com/en/microbiology/listeria-monocytogenes/)
- [Streptococcus pyogenes](https://durgical.com/en/microbiology/streptococcus-pyogenes/)
- [Vibrio vulnificus and Vibrio parahaemolyticus](https://durgical.com/en/microbiology/vibrio-vulnificus-and-vibrio-parahaemolyticus/)
- [Enterococcus](https://durgical.com/en/microbiology/enterococcus/)

## Related conditions 3

- [Hand infections (paronychia, felon, flexor tenosynovitis)](https://durgical.com/en/conditions/hand-infections/)
- [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/)
- [Septic Arthritis of the Knee](https://durgical.com/en/conditions/septic-arthritis-of-the-knee/)

[← Back to the group: Gram-positive rods](https://durgical.com/en/microbiology/groups/gram-positive-rods/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Erysipeloid - Infectious Disease - MSD Manual Professional Edition](https://www.msdmanuals.com/professional/infectious-diseases/gram-positive-bacilli/erysipelothricosis) (MSD Manual Professional Edition, 2025); [Did the updated Duke criteria missed Erysipelothrix rhusiopathiae from the list of typical microorganisms causing infective endocarditis?](https://infezmed.it/media/articoli-html/Vol_31_4_2023_1.html) (Le Infezioni in Medicina, 2023).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/microbiology/erysipelothrix-rhusiopathiae/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/erysipelothrix-rhusiopathiae/