The Canadian Encyclopedia — neutral, cited, updated
July 26, 2026Sources cited
Canadianwire.
Canada’s encyclopedia & explainer
HomeScience & NatureBacteriologySerratia marcescens
Science & Nature • Bacteriology

Serratia marcescens

Serratia marcescens is a species of Gram-negative, rod-shaped bacteria in the family Yersiniaceae.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Serratia marcescens is a species of Gram-negative, rod-shaped bacteria in the family Yersiniaceae. It is commonly found in the environment and is known as an opportunistic pathogen that can cause hospital-acquired infections in humans. The species is also notable for producing a red pigment called prodigiosin.

Taxonomy and characteristics

Serratia marcescens belongs to the genus Serratia in the family Yersiniaceae. It is described as a Gram-negative, rod-shaped, facultatively anaerobic bacterium.

Ecology and appearance

The species occurs widely in the environment, including soil, water, plants, and animals. Its prodigiosin pigment can produce distinctive pink, red, or orange coloration on moist surfaces.

Medical importance

S. marcescens is an opportunistic pathogen and is often linked to nosocomial infections. Reported infections include urinary tract infections, wound infections, pneumonia, bloodstream infection, and meningitis.

History

The species was first identified in the early 19th century by Bartolomeo Bizio, who observed its characteristic red discoloration in food material.

Key facts

  • It is a Gram-negative, rod-shaped bacterium.
  • It is a facultative anaerobe and an opportunistic pathogen in humans.
  • It is associated with hospital-acquired infections, including urinary tract infections, wound infections, and bacteremia.
  • It produces the red pigment prodigiosin, which can cause pink to red discoloration in damp environments.
  • It is found in soil, water, plants, animals, and other moist environments.
🍁
Canadian context

Serratia marcescens is relevant to Canadian readers mainly through hospital infection control and environmental microbiology, since it is an opportunistic pathogen associated with healthcare settings.

Frequently asked questions

What is Serratia marcescens?
A species of Gram-negative, rod-shaped bacteria that is best known as an opportunistic human pathogen and for producing a red pigment.
Where is Serratia marcescens found?
It is found in the environment, including soil, water, plants, animals, and moist indoor surfaces such as showers and basins.
What infections can it cause?
It can cause hospital-acquired urinary tract infections, wound infections, bacteremia, pneumonia, meningitis, and other infections, especially in vulnerable patients.
Why does it look red or pink?
The species produces prodigiosin, a red pigment that can create pink-to-red discoloration on damp surfaces.
Is Serratia marcescens dangerous to healthy people?
It is mainly an opportunistic pathogen and is more likely to cause disease in hospitalized, immunocompromised, or critically ill people.

References

  1. Wikipediahttps://en.wikipedia.org/wiki/Serratia_marcescens
    Supports: Basic taxonomy, morphology, opportunistic pathogen status, and hospital-acquired infection associations.
  2. ScienceDirecthttps://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/serratia-marcescens
    Supports: Historical identification, pathogenic significance, and infection types.
  3. CDC Emerging Infectious Diseaseshttps://wwwnc.cdc.gov/eid/article/25/11/et-2511_article
    Supports: Pigment prodigiosin, damp-environment occurrence, and nosocomial infections.
  4. MicrobeWikihttps://microbewiki.kenyon.edu/index.php/Serratia_marcescens
    Supports: Environmental distribution and discovery history.
  5. Infectious Disease Advisorhttps://www.infectiousdiseaseadvisor.com/ddi/serratia-marcescens/
    Supports: Environmental occurrence, prodigiosin-related coloration, and infection overview.
  6. Cleveland Clinichttps://my.clevelandclinic.org/health/diseases/serratia-marcescens
    Supports: Clinical overview, hospital-acquired transmission context, and common infection types.
  7. PubMed Centralhttps://pmc.ncbi.nlm.nih.gov/articles/PMC12691863/
    Supports: Gram-negative, facultatively anaerobic bacillus classification and opportunistic pathogen description.