PetriKey

Bacterium

Staphylococcus epidermidis

Coagulase-negative skin flora clue

STAFF-ih-lo-KOK-us EP-ih-der-MID-is

Gram positivegram-positivecoccicatalasecoagulase-negativebiofilm

High-yield clue

Clusters + catalase positive + coagulase negative points away from S. aureus.

Overview

A coagulase-negative staphylococcus frequently used in study questions about normal skin flora and device-associated biofilm concepts.

Classification

  • Gram-positive
  • Cocci
  • Clusters
  • Coagulase-negative staphylococcus

Lab & identification clues

  • Catalase positive
  • Coagulase negative
  • Novobiocin-sensitive distinction is commonly taught

Associations

  • Skin flora
  • Biofilm vocabulary
  • Device-associated infection concepts in educational cases

Commonly confused with

  • Staphylococcus aureus
  • Staphylococcus saprophyticus

Your notes

Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.

OpenStax: Microbiology 2e organism classification foundationssourceNCBI Bookshelf: Medical Microbiology organism chapterssourceCDC: CDC disease and public-health topic pagessource