The Microbiology of Postoperative Spine Surgical Site Infections: An Institutional Experience of 170 cases.

BACKGROUND

Postoperative spine infections are surgical site infections that develop following spine surgery and often require operative management to reduce infection burden and provide source control. Intraoperative cultures are essential for identifying pathogens and guiding antimicrobial therapy. We characterized the microbiology and antimicrobial treatment of patients with postoperative spine infections at our institution.

METHODS

We performed a retrospective review of patients with postoperative spine surgical site infections (SSI) requiring surgical intervention between 2015 and 2025. Intraoperative culture data and postoperative antibiotic regimens were recorded. Associations between chronic antibiotic suppression and presence of an extra-spinal infection source, microbiologic concordance between extra-spinal and intraoperative cultures, and polymicrobial infection were evaluated.

RESULTS

Between 2015 and 2025, 170 of 4921 patients (3.5%) underwent surgical management for postoperative spine SSI. Mean age was 58.7 years (SD 18.3), with 93 females (55%). Of these, 112 were elective (65.9%) and 113 were primary surgeries (66.5%). Patients had a mean of 2 reoperations (SD 1.9). 111 patients (65.3%) had positive intraoperative cultures. Among them, 62 infections were monomicrobial (55.9%), with 14 MRSA and 18 MSSA. Of the 170 cases, 38 (22.4%) had an extra-spinal infection source, with blood (19, 50%) and urine (22, 57.9%) being most common. Of the 111 patients with positive cultures, 29 (26.1%), had an extra-spinal infection source, and nearly half had overlapping microbiology (13, 44.8%). 35 patients (20.6%) required lifelong oral antibiotics. Chronic antibiotic therapy was significantly associated with presence of an extra-spinal infection source, but not organism concordance or polymicrobial infection.

CONCLUSION

Among 170 patients with postoperative spine SSI, two-thirds had positive intraoperative cultures, with MRSA and MSSA being most common. High rates of concordance were observed between extra-spinal infection sources and intraoperative cultures. Still, one-fifth of patients required lifelong oral antibiotics for infection control.