Pyogenic spondylodiscitis from oral odontogenic origins: a frequently overlooked entity

Primary spondylodiscitis occurs through the hematogenous spread of a pathogen entering the body via a point of entry. The infection's origin often remains unclear. During dental procedures or through minor traumas, oral bacteria can enter the bloodstream and disseminate throughout the body.

This study's objective was to further investigate the role of odontogenic (ie, teeth-related) causes of spondylodiscitis, especially in cases where another infective focus could not be identified initially.

Retrospective analysis.

In a cohort of 340 consecutive patients with primary spondylodiscitis treated at a Level I Spine Center from January 1, 2018 to December 31, 2022, those with oral bacteria in blood cultures or disc tissue samples and available orthopantomograms (OPG, ie, panoramic X-ray of the teeth) were retrospectively reevaluated for odontogenic origins. Patients with secondary spondylodiscitis from a previous operation (< 3 months) in the same segment were excluded.

Radiological features indicating an infectious dental focus included apical radiolucency of the tooth, impacted teeth, residual roots, and vertical or cup-shaped bone loss.

Patients' medical records, imaging data, laboratory, microbiological and histopathological findings, and surgical reports were analyzed. The term oral bacteria refers to the whole microbiome of the oral cavity. Periodontal bacteria are bacterial species implicated in periodontal diseases. For further classification, periodontal bacteria were assigned to one of five complexes previously described.

The most frequent infective source was an infection of the major joints of the extremities (14.1%), followed by ulcers of the extremities (10.3%) and urosepsis (10.0%). An odontogenic origin was initially identified in 8.9%. In 33.1% of cases, the source of infection was not found. Oral bacteria were found in 38 cases (13.3%) of 286 (ie, all cases with a positive pathogen detection). Six of these had an identified focus of the throat, and six had an initially clear dental focus. Of the remaining 26 cases, OPG was available for 14. Reevaluation of OPG revealed an odontogenic focus in 9 out of 14 cases (64.3%). Two of these cases had a concomitant infective focus, while in 7 cases, no infective source was initially found.

An odontogenic origin for spondylodiscitis was more prevalent than initially presumed, particularly in patients where no source was identified at first sight. We therefore recommend a thorough diagnostic dental work-up as a standard procedure for patients with primary spondylodiscitis.