# Isolated Fusobacterium nucleatum Growth in the Blood Culture of a Middle-Aged Man With Lumbar Discitis, Surrounding Psoas Abscesses, and an Inferior Vena Cava Thrombus

## TL;DR

A rare case of spinal infection caused by Fusobacterium nucleatum is reported in a middle-aged man with symptoms initially mistaken for a urinary tract infection.

## Contribution

This case highlights the rare implication of F. nucleatum in spinal infections and the importance of considering it in differential diagnosis.

## Key findings

- Fusobacterium nucleatum was isolated from blood cultures in a patient with lumbar discitis and psoas abscesses.
- Initial misdiagnosis as pyelonephritis delayed appropriate treatment for the spinal infection.
- No evidence of tuberculosis or other common infections was found, confirming F. nucleatum as the causative agent.

## Abstract

Pyogenic spinal infections (PSI) have an incidence of 0.5-2.2 cases per 100,000 population, though diagnosis can be delayed by up to three months. The incidence of Fusobacterium nucleatum bacteremia is rare, occurring in 0.22-0.34 cases per 100,000 population, whilst its implication in spinal infections is rarer still. A man in his 60s with a background of chronic lower back pain presented to the emergency department with a two-week history of worsening back pain associated with fever and difficulty voiding. He was initially managed as pyelonephritis due to the recent history of urinary tract infection (UTI) with fever and flank pain. However, there were radiculopathy and bilateral pain on hip flexion with reduced power on the right side. The light-touch sensation was reduced over the right hallux and distal L4 dermatome. These neurological deficits associated with deranged infective markers made a diagnosis of discitis plausible. Discitis and native vertebral osteomyelitis (NVO) should be suspected in patients reporting a fever and back pain of recent onset or increasing in severity. Once discitis was confirmed, the patient was subsequently tested for tuberculosis (TB) using a T-SPOT, human immunodeficiency virus (HIV), hepatitis B virus, and hepatitis C virus, with no positive findings, but in the days following, blood cultures yielded F. nucleatum. Guided by knowing the natural reservoirs in the body, establishing the source of F. nucleatum could be achieved through head and neck imaging and investigating the gastrointestinal tract for malignant or inflammatory processes.