Treatment of Fusobacterium Infections

Metronidazole is the recommended first-line treatment for Fusobacterium infections, with clindamycin being an effective alternative option. 1, 2

Microbiology and Clinical Relevance

Fusobacterium species are anaerobic gram-negative bacilli that are part of the normal oropharyngeal and gastrointestinal flora but can cause serious infections 2
Common Fusobacterium species causing infections include F. necrophorum and F. nucleatum, with distinct infection patterns depending on the species 3
These organisms are frequently isolated in mixed infections, with approximately 75% of cases involving multiple bacterial strains 3

Metronidazole is highly effective against Fusobacterium species and is FDA-approved for skin and skin structure infections caused by Fusobacterium species 1
Metronidazole provides excellent coverage against anaerobic bacteria, including Fusobacterium, with minimal resistance reported 3
For serious infections, intravenous metronidazole is typically administered initially, followed by oral therapy at the physician's discretion 1

Clindamycin is an effective alternative with excellent activity against Fusobacterium species, particularly in patients who cannot tolerate metronidazole 4, 5
Beta-lactam/beta-lactamase inhibitor combinations (such as amoxicillin-clavulanate or piperacillin-tazobactam) are also effective against Fusobacterium species with minimal resistance 3
Carbapenems demonstrate excellent activity against Fusobacterium and can be used in severe infections or when broader coverage is needed 3

For pleural infections involving Fusobacterium (particularly in older children and teens), metronidazole should be added to standard antibiotic regimens unless co-amoxiclav or clindamycin are already being used 4
Suitable treatment options for pleural infections include:
- Cefuroxime plus metronidazole
- Co-amoxiclav alone
- Clindamycin alone (especially in penicillin-allergic patients) 4

For peritonsillar abscesses and acute tonsillitis where F. necrophorum is commonly isolated, a combination of surgical drainage (when indicated) and antibiotics is recommended 6
For acute otitis where other Fusobacterium species predominate, appropriate antibiotic therapy with metronidazole or clindamycin is effective 6

For Fusobacterium endocarditis, metronidazole (61.9% of cases) is the most commonly used antimicrobial agent 2
Surgical management may be required in approximately 24% of Fusobacterium endocarditis cases 2

Recent studies show approximately 5% of F. nucleatum and F. necrophorum isolates demonstrate penicillin G resistance 3
Moxifloxacin resistance varies widely among Fusobacterium strains (4.6-100%) 3
All Fusobacterium isolates remain sensitive to beta-lactam/beta-lactamase inhibitors, carbapenems, and metronidazole, making these reliable options 3

For skin and soft tissue infections: 7-14 days of therapy is typically recommended 4
For more serious infections like endocarditis or bone/joint infections, longer courses (4-6 weeks) may be necessary 1
Treatment should be continued until clinical improvement is observed and then for an appropriate duration based on the site and severity of infection 4

In polymicrobial infections (common with Fusobacterium), additional antimicrobial coverage may be needed for aerobic organisms 1
Poor dental hygiene or recent dental work is a common predisposing factor for Fusobacterium infections, particularly endocarditis 2
Early diagnosis and appropriate antimicrobial treatment are crucial for optimal outcomes in Fusobacterium infections 2