Staphylococcus epidermidis !
- Bacterium
- Gram-positive
- Exam priority: medium
A normal skin bacterium that infects catheters, prostheses and artificial valves by forming a sticky biofilm.
Updated 2026-11-01
Also called: coagulase-negative staphylococcus
At a glance
- Gram
- Gram-positive
- Shape
- Cocci in clusters
- Oxygen
- Facultative anaerobe
- Family
- Staphylococcaceae
- Stain
- Gram positive; catalase positive, coagulase negative
Morphology
- Gram-positive cocci in clusters
- White, non-haemolytic colonies
- Novobiocin sensitive
Transmission
- The patient's own skin flora
- Enters when catheters, prostheses or shunts are placed
- Staff hands during procedures
Isolation precautions
What the care team adds to standard precautions.
- Standard
Virulence factors
- Polysaccharide biofilm on plastic and metal
- The biofilm shields it from antibiotics and host defences
- Frequent methicillin resistance
Diseases it causes
- Prosthetic valve endocarditis Infective endocarditis →
- Infections of venous catheters, shunts and joint prostheses
Clinical picture
- Fever in a patient with a catheter or prosthesis
- Indolent prosthetic joint infection
Diagnosis
- Coagulase negative, novobiocin sensitive
- Several positive blood cultures to tell infection from contamination
- A frequent contaminant of a single blood culture
Treatment
It is often methicillin resistant, so vancomycin is common while susceptibility is pending. Removing or exchanging the infected device is often needed because the biofilm prevents cure with antibiotics alone.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Aseptic technique when inserting and handling catheters
- Removing catheters that are no longer needed
- Hand hygiene
Test yourself
Think of the answer, then tap the question to see it.
Which virulence factor lets S. epidermidis infect prostheses?
A polysaccharide biofilm that sticks to plastic and metal surfaces.
Which antibiotic disc separates S. epidermidis from S. saprophyticus?
Novobiocin: S. epidermidis is sensitive and S. saprophyticus is resistant.
How is a single positive blood culture for S. epidermidis interpreted?
Often as skin contamination; several positive cultures and clinical context are needed.
Related
Related conditions
← Back to the group: Staphylococci
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Staphylococcal Infections (MedlinePlus (NLM), 2025); Endocarditis: MedlinePlus Medical Encyclopedia (MedlinePlus (NLM), 2024).
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Representative model, for educational purposes only.