Fusobacterium necrophorum


Anaerobic Gram-Negative Bacilli
>Bacteroides fragilis (most important clinically)
    [Other Bacteroides species  – less common clinically:  (B. acidifaciens, B. gracilis,
         B. oris, B. ovatus,  B. pyogenes , B. stercoris, B. vulgatus)]
>Bacteroides melaninogenicus (reclassified and split into Prevotella melaninogenica
     and Prevotella intermedia.)
>Fusobacterium necrophorum Led
>Porphyromonas gingivalis


  • Anaerobic, Gram-negative bacteria, similar to Bacteroides.
  • Rod-shaped baccilli with pointed ends.
  • Strains of Fusobacterium contribute to several human diseases, including periodontal diseases, Lemierre’s syndrome, and topical skin ulcers.
  •  In contrast to Bacteroides species, Fusobacteria have a potent lipopolysaccharide.


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Important considerations:  The choice of an agent should be based on local antimicrobial sensitivities, site of infection, cost, and comorbid conditions.   Generally, the most common agents/regimens are listed first.

Severe cases: consider combination therapy:  infections may be polymicrobial, and other organisms can mimic fusobacteriosis.   Also MIC/susceptibility testing should generally be performed for all serious infections.

  1. Metronidazole 500mg IV/PO every 6 hours
  2. Clindamycin  Usual: 600-900mg IV every 6 or 8 hours or 150 to 450mg orally every 6-8 hours
  3. Piperacillin-tazobactam (Zosyn ®)  3.375 to 4.5  grams IV q6h
  4. Imipenem 500mg IV every 6 hours [Range: 250-1000 mg q6-8h]
Fusobacterium necrophorum