Bacterium
Fusobacterium necrophorum
Lemierre-syndrome anaerobe
few-zoh-bak-TEER-ee-um nek-ROF-or-um
High-yield clue
Pharyngitis in a young adult followed by internal jugular vein septic thrombophlebitis and septic emboli is the classic Lemierre-syndrome clue for this anaerobe.
Overview
A Gram-negative anaerobic, spindle-shaped oral commensal that is the classic teaching cause of Lemierre syndrome. It illustrates how a throat infection can spread to nearby great vessels.
Classification
- Gram-negative
- Anaerobe
- Fusiform / spindle-shaped rod
- Oral flora
Lab & identification clues
- Gram-negative anaerobe
- Spindle (fusiform) rods on stain
- Blood culture in septic emboli
- Oropharyngeal flora
Associations
- Lemierre syndrome
- Pharyngitis in young healthy adults
- Internal jugular thrombophlebitis with septic pulmonary emboli
Commonly confused with
- Streptococcus pyogenes pharyngitis
- Bacteroides fragilis
Frequently asked questions
What is Fusobacterium necrophorum?
A Gram-negative anaerobic, spindle-shaped oral commensal that is the classic teaching cause of Lemierre syndrome. It illustrates how a throat infection can spread to nearby great vessels.
What is the Gram stain of Fusobacterium necrophorum?
Fusobacterium necrophorum is Gram negative.
What are the lab clues for Fusobacterium necrophorum?
Lab clues for Fusobacterium necrophorum include Gram-negative anaerobe, Spindle (fusiform) rods on stain, Blood culture in septic emboli, and Oropharyngeal flora.
What is Fusobacterium necrophorum commonly confused with?
Fusobacterium necrophorum is commonly confused with Streptococcus pyogenes pharyngitis and Bacteroides fragilis.
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.