Bad news itself or just the messenger? The high mortality of Fusobacterium spp. infections is related to disseminated malignancy and other comorbidities

BACKGROUND Fusobacterium species are pleomorphic, obligate anaerobic gram-negative bacilli. They are difficult to culture and grow slowly. If antibiotic treatment is initiated prior to blood cultures, the bacteria might evade detection. This is a comprehensive report on mortality in non-bacteraemia fusobacterial infection. METHODS Data were collected retrospectively in adults having a positive culture with Fusobacterium spp. admitted during 2000-2012 at the medical department. Data on culture specimens, number of cultures, admission and culture dates, patient age, gender, clinical disease, Charlson's index of co-morbidity, CRP level and survival were obtained. For comparison, we traced 60 consecutive, similarly obtained cultures from 2009 to 2010 containing Staphylococcus aureus. RESULTS Within a 12-year period, we identified 28 patients with a positive culture of Fusobacterium spp. in a medical ward serving a population of 220,000. Only a minority (39%) had a positive blood culture, and 54% had focus in respiratory tract or pleura. Overall 6-month mortality was 32%, and unrelated to subspecies, treatment or anatomic location but significantly related to age >60 years, admission for severe, acute illness, and comorbidity, especially metastatic malignancy. Comparison between infection with Fusobacterium spp. and S. aureus showed that Fusobacterium spp. infections were predominantly community acquired, while S. aureus were both community and hospital acquired. Overall mortality for both bacterial infections increased significantly with age and current malignant disease. S. aureus-infected patients carried a significantly higher mortality. CONCLUSION Our data support that Fusobacterium spp. infection is a marker for significant, chronic disease rather than carrying a poor prognosis per se.