First case series to describe clinical infections with Fusobacterium gonidiaformans

Fusobacterium species are anaerobic Gram-negative bacilli. Infections with F. necrophorum and the associated Lemierre’s syndrome are the most commonly described in the literature, however the role of F. gonidiaformans in disease is less well characterised. We present the first case series to describe infections with F. gonidiaformans . The laboratory database for a Scottish health board was searched to identify samples in which F. gonidiaformans had been isolated between 2019 and 2022. Clinical and laboratory documentation was reviewed. 26 isolates were identified in the time period studied corresponding to 25 cases. Most samples were polymicrobial (85%). No beta-lactam, metronidazole or clindamycin resistance was detected. 17 of the 25 cases were found to have clinical infection. Median age was 37 years with interquartile range (IQR) 33–50, 11 cases (65%) were female. The most common clinical syndrome was abscess (59%) followed by infected thrombophlebitis (18%). Median duration of antibiotic therapy was 14 days (IQR: 11–16). The majority of cases with abscess underwent source control (90%). Five cases were managed as outpatients only, median hospital stay for admitted cases was 7 days (IQR 5–15), and 2 cases required ICU admission. There was no mortality among the cases found to have clinical infection. Fusobacterium gonidiaformans was isolated from blood cultures in 4 cases, 3 of which were cases with infected thrombophlebitis in patients who injected drugs. This series summarises 17 cases of F. gonidiaformans infection. Clinical abscess was found in the majority of cases, and thrombophlebitis in most cases of bacteraemia. Further studies will be required to establish clinical and epidemiological risk factors for clinical disease.