Bacterium
Cutibacterium acnes
Acne & prosthesis anaerobe (formerly Propionibacterium)
koo-tih-bak-TEER-ee-um AK-neez
High-yield clue
Slow-growing anaerobic skin rod tied to acne and to indolent prosthetic (especially shoulder) infections, and a notorious blood-culture contaminant that requires long incubation.
Overview
A slow-growing anaerobic Gram-positive rod of the skin (renamed from Propionibacterium acnes) that lives in pilosebaceous follicles. It is a key teaching example of a skin commensal that is both an acne contributor and an indolent implant pathogen.
Classification
- Gram-positive
- Rod
- Anaerobic / aerotolerant
- Skin flora
Lab & identification clues
- Slow-growing anaerobe needing prolonged incubation
- Gram-positive rod
- Contaminant vs true pathogen framing
- Biofilm on implants
Associations
- Acne vulgaris in pilosebaceous units
- Prosthetic joint / shoulder implant infection
- Blood-culture contaminant framing
Commonly confused with
- Coagulase-negative staphylococci contaminants
- Corynebacterium species
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.