Hepatic and Pulmonary Abscesses From Fusobacterium nucleatum Infection

Discussion. Fusobacterium species are gram-negative and non–spore-forming anaerobic bacteria. F nucleatum and Fusobacterium necrophorum are the most commonly isolated bacteria in this group.¹ F nucleatum is a prevalent part of the oral flora and is usually found in the oropharynx, while F necrophorum is usually found in the appendix.²

F nucleatum is a rare cause of liver abscess.^2,3 It also causes endodontic abscesses.⁴ Historically, Fusobacterium bacteremia is associated with Lemierre syndrome, first recognized in 1936 by André Lemierre as an oropharyngeal infection causing thrombophlebitis of the internal jugular vein and septic emboli to various organs.⁵ Recent literature has described a gastrointestinal variant of Lemierre syndrome in which F nucleatum causes septic thrombophlebitis of the portal vein and subsequent portal vein hypertension.^6-8

A recent literature review of liver abscesses showed infection with F nucleatum in 22 of 48 reported cases.² The presumed source was the oral cavity, regardless of the presence of dental disease. Fewer cases were presumed to originate from the lower gastrointestinal tract.² In another published report, F nucleatum bacteremia was detected in 2 of 4 patients with hematologic malignancies with oral mucositis; in another case, the peritonsillar region and soft palate were edematous.⁹ Another case report reported a liver abscess in a patient with periodontal disease and dental caries.³ The authors presumed that it was hematogenous spread from the oropharynx via the venous system, then traveling via the hepatic artery and seeding the liver.³

Fusobacterium bacteremia risk factors and outcomes of the infection have been analyzed. F nucleatum bacteremia was found in 61% of 72 cases over 11 years in one review.¹⁰ F necrophorum bacteremia was not found in patients younger than 40, and patients’ median age was 53.5 years.¹⁰ Other risk factors were malignancy, dialysis, dementia, chronic obstructive lung disease, diabetes, and heart disease. Antibiotic resistance is uncommon among Fusobacterium; no cases showed resistance to metronidazole or clindamycin, and only few had penicillin resistance. Mortality in these patients more likely was a result of associated comorbidities.¹⁰

The risk factors in our patient were old age, poor dentition, and hemodialysis. We believe the source of the fusobacterial pulmonary and hepatic abscesses to be the oropharynx. The patient recovered successfully with antibiotic therapy and abscess drainage.

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