Invasive Fusobacterium necrophorum infections and Lemierre's syndrome: the role of thrombophilia and EBV.

The purpose of this investigation was to describe the clinical spectrum of invasive Fusobacterium necrophorum infections and Lemierre's syndrome, to examine the role of underlying thrombophilia and concomitant mononucleosis in Lemierre's syndrome, and to describe thromboembolic complications. Patients with invasive F. necrophorum infections were identified either prospectively or retrospectively through the regional database of clinical microbiology from 2000 to 2015. Patient records were reviewed and blood samples from patients with Lemierre's syndrome were collected for Epstein-Barr virus (EBV) serology and screening for thrombophilia. Of the 65 patients included, 33 had Lemierre's syndrome. Of the remaining 32 patients, other infections of the respiratory tract and abdominal or urogenital infections were most common. Patients with Lemierre's syndrome or other tonsillar infections were younger than patients from the other groups. For Lemierre's syndrome, the 26 patients with severe sepsis on admittance had longer duration of symptoms. Three of five patients who developed distant manifestations had more than 14 days of symptoms. Jugular vein thrombosis was verified in 14 patients, two of whom developed serious complications. Three of 26 patients tested had factor V Leiden mutation, corresponding to the background prevalence. One of 22 patients tested had a concomitant EBV infection. This study confirms earlier studies of the clinical spectrum caused by F. necrophorum. For Lemierre's syndrome, the study adds to the knowledge on thromboembolic outcome, demonstrating that jugular vein thrombosis may cause severe complications. The time to treatment seems to be important for the risk of severe disease. In this study, concomitant EBV infection or underlying thrombophilia was uncommon.