[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Streptococci and enterococci](https://durgical.com/en/microbiology/groups/streptococci-and-enterococci/) › Enterococcus

[Microbiology](https://durgical.com/en/microbiology/) · [Streptococci and enterococci](https://durgical.com/en/microbiology/groups/streptococci-and-enterococci/)

# Enterococcus

- Bacterium
- Gram-positive
- Contact
- Exam priority: medium

Gut cocci that cause urinary infection, endocarditis and hospital infections; some strains resist vancomycin (VRE).

Updated 2026-11-01

Also called: Enterococcus faecalis, Enterococcus faecium, VRE (vancomycin-resistant enterococcus)

## Key points

- Intrinsic resistance to cephalosporins.
- Grows in bile and 6.5 % NaCl; PYR positive.
- VRE: D-Ala-D-Ala becomes D-Ala-D-Lac.
- VRE: contact precautions; linezolid or daptomycin.
- VRE colonisation is not treated with antibiotics.

## At a glance

**Gram**
Gram-positive

**Shape**
Cocci in pairs and short chains

**Oxygen**
Facultative anaerobe

**Family**
Enterococcaceae

**Stain**
Gram positive; catalase negative; PYR positive

## Morphology

- Gram-positive cocci in pairs or chains
- Grows on bile esculin and in 6.5 % NaCl
- Gamma or variable haemolysis

## Transmission

- The patient's own gut flora
- In hospital: contaminated hands, surfaces and equipment
- VRE does not spread through the air

### Isolation precautions

What the care team adds to standard precautions.

**Contact**
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

## Virulence factors

- Intrinsic resistance to cephalosporins
- Acquired vancomycin resistance (van genes: D-Ala-D-Lac)
- Biofilm on urinary catheters

## Diseases it causes

- Urinary tract infection, especially with a catheter [Urinary tract infection (acute cystitis) →](https://durgical.com/en/conditions/urinary-tract-infection/)
- Infective endocarditis (E. faecalis) [Infective endocarditis →](https://durgical.com/en/conditions/infective-endocarditis/)

## Clinical picture

- Catheter-associated urinary infection
- Bacteraemia in hospitalised patients
- Subacute endocarditis in older adults, sometimes after urological or bowel procedures

## Diagnosis

- Culture: growth on bile esculin and in 6.5 % NaCl
- PYR positive
- Susceptibility testing to ampicillin and vancomycin

## Treatment

Ampicillin is preferred for susceptible E. faecalis; in endocarditis it is combined with an aminoglycoside or with ceftriaxone. E. faecium is often ampicillin resistant. VRE is treated with linezolid or daptomycin. Cephalosporins never cover enterococci.

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

In Pharmacology:

- [Ampicillin](https://durgical.com/en/pharmacology/ampicillin/)
- [Vancomycin](https://durgical.com/en/pharmacology/vancomycin/)
- [Linezolid](https://durgical.com/en/pharmacology/linezolid/)
- [Daptomycin](https://durgical.com/en/pharmacology/daptomycin/)

## Prevention

- Hand hygiene
- Contact precautions for patients with VRE
- Antibiotic stewardship
- Removing unneeded catheters

## Memory aid

Enterococcus is the off-roader: it shrugs off bile, salt and cephalosporins, and against vancomycin it swaps one letter (Ala for Lac) and slips away too.

## Test yourself

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

## Why do cephalosporins fail against enterococci?

Intrinsic resistance: their PBPs have low affinity for cephalosporins.

## Which molecular change makes enterococci vancomycin resistant?

The peptidoglycan end changes from D-Ala-D-Ala to D-Ala-D-Lac, which vancomycin binds poorly.

## Which precautions does a patient with VRE need?

Standard precautions plus contact precautions.

## Which two growth tests identify enterococci?

Growth on bile esculin agar (which it hydrolyses) and in broth with 6.5 % NaCl.

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

## Related

- [Viridans streptococci](https://durgical.com/en/microbiology/viridans-streptococci/)
- [Staphylococcus aureus](https://durgical.com/en/microbiology/staphylococcus-aureus/)

## Related conditions

- [Urinary tract infection (acute cystitis)](https://durgical.com/en/conditions/urinary-tract-infection/)
- [Infective endocarditis](https://durgical.com/en/conditions/infective-endocarditis/)

## 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.

**Contact**
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

**Droplet**
Surgical mask within about a metre; single room.

**Airborne**
N95 respirator and a negative-pressure room.

[← Back to the group: Streptococci and enterococci](https://durgical.com/en/microbiology/groups/streptococci-and-enterococci/)

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

Sources: [Vancomycin-resistant Enterococci (VRE) Basics](https://www.cdc.gov/vre/about/index.html) (CDC, 2024); [Endocarditis: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/001098.htm) (MedlinePlus (NLM), 2024); [Urinary tract infection - adults](https://medlineplus.gov/ency/article/000521.htm) (MedlinePlus (NLM), 2024).

## **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/enterococcus/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/enterococcus/