Fusobacterium bloodstream infections: A literature review and hospital-based case series

Infections with Fusobacterium, an anaerobic bacterium, have various clinical presentations, including bacteremia and Lemierre syndrome. Here, we report a case series of Fusobacterium bacteremia (FBB) from the largest academic center in Riyadh, Saudi Arabia, and provide a review of cases in the available literature.

Records were retrospectively reviewed for all patients with at least one blood culture positive for Fusobacterium spp. admitted at King Khalid University Hospital, Riyadh, Saudi Arabia, between May 2015 to April 2019.

We conducted a MeSH Search on MedLine using the following terms: ("Bacteremia"[Mesh]) AND "Fusobacterium"[Mesh] for studies conducted from January 1, 1990, until March 30, 2019, excluding articles that lacked adequate clinical or microbiological details for individuals patients. Odds ratios and results of Chi-Square testing obtained in SPSS (Version 23.0, SPSS, Inc., Chicago, IL, USA) were considered statistically significant at p-values < 0.05.

Seven cases from our center and 205 cases from the literature were reviewed in this first reported case series for the region. Our patient series was similar to previous ones in terms of median age (45 vs. 45.5 years) and male predominance (85% vs. 65.9%). The species of Fusobacterium cultured from our cases were F. nucleatum (4 cases), F. varium (1 case), F. mortiferum (1 case), and one that could not be identified to the species level (1 case). We also report one case of FBB with renal vein thrombosis resembling that of atypical Lemierre syndrome. Analysis of literature cases revealed that bacteremia caused by the species most commonly associated with FBB, F. necrophorum, tended to be present in patients less than 40 years of age and be associated with head and neck infections and other complications, whereas F. nucleatum tended to affect people more than 40 years of age and be associated with mortality.

Although FBB is rarely reported in the literature, this case series and review of the literature suggests it is associated with morbidity and mortality. The type and duration of therapy used in these cases are underreported. Further research is needed to determine the most appropriate screening approach for FBB-associated complications and explore the relationship between FBB and specific malignancies, as well as optimal treatment type and duration.