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
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.