Short Blood Culture Time-to-Positivity in Fusobacterium necrophorum Bacteremia is Associated with Lemierre’s Syndrome

Background: Short blood culture time-to-positivity (TTP) has been shown to correlate with infective endocarditis, yet TTP has never been investigated in Fusobacterium necrophorum bacteremia. Since Lemierre’s syndrome occurs after an oropharyngeal infection with the development and subsequent embolization of septic thrombophlebitis of the internal jugular vein, it could also be considered an endovascular infection, similar to infective endocarditis. The purpose of this study was to investigate if Lemierre’s syndrome was associated with shorter TTP in F. necrophorum-bacteremia.
Methods: Patients with F. necrophorum bacteremia in the Skåne Region, Sweden from January, 2012 to December, 2020 were enrolled. Exclusion criteria were lack of data on TTP, non-immediate incubation of blood cultures, and polymicrobial growth in the anaerobic bottles. TTP was defined as the time from start of incubation to the first signal of positivity. From 2012-2014 the BacT/ALERT® blood culture system (bioMérieux, Inc.) was used in the Skåne Region with blood culture cabinets available only at the tertiary hospital of the region. From 2015, the BACTEC™ FX blood culture system (BectonDickinson) were introduced at all five major hospitals in the region, along with blood culture cabinets for immediate incubation. Clinical data was collected through electronic chart review. Lemierre’s syndrome was defined as a positive blood culture with F. necrophorum, a preceding oropharyngeal infection, and a radiologically confirmed diagnosis of neck venous thrombosis or signs of septic pulmonary embolism.
Results: 41 episodes of F. necrophorum bacteremia were analyzed, of which 15 (37%) occurred in patients with Lemierre’s syndrome. TTP was significantly shorter in patients with vs. without Lemierre’s syndrome 21 h (17–25 95CI) vs. 27 h (23–31 95CI) (p=0.03, Student’s t-test).
Conclusion: In patients with F. necrophorum bacteremia, patients with Lemierre’s syndrome had shorter TTP, yet substantial overlap was seen. These findings are in line with the interpretation of Lemierre’s syndrome as an endovascular infection.