Suppressive Antibiotic Therapy for Spinal Hardware Infection: A Retrospective Cohort Study

Background: Spinal hardware infection (SHI) is one of the most devastating complications of spine surgery with challenging and undefined antibiotic treatment modalities. Methods: Retrospective cohort study of patients ≥18 years of age who underwent surgery for the treatment of SHI at a university center between 1 ^st January2015, to 1 ^st January 2020. The aim was to determine the appropriate duration of suppressive antibiotic therapy (SAT) for SHI based on recurrent infection rate on SAT, rate of adverse drug reaction (ADR) from SAT, and rate of antibiotic resistance to SAT in patients with SHI. Results: The median age of the 82 patients who met eligibility criteria for the study was 61 years (53.2–72.5), 55% were female, 59.8% had multimorbidity and 53.7% had early infection . Staphylococcus aureus was the most common cultured organism (37.8%) and 29 (35.4%) of patients had bacteremia. 54 (65.8%) received SAT with a median duration of 52 weeks (12 to 191 weeks). 12 (14.5%) had recurrence, while 8 (9.7%) developed recurrence on SAT. Neither SAT nor SAT duration (<24 weeks, 24-52 or >52 weeks) was associated with recurrence in early or late infection, regardless of hardware status. There was a non-significant higher recurrence rate with partial hardware revision, 7.3% (OR 6.30 [0.70–57.07]) and full hardware retention, 6.1% (OR 3.62 [0.39–33.30]) compared to complete hardware removal, (1.2%). ADR occurred in 6 (11.1%) of patients on SAT and in 11 (13.6%) of patents while on intravenous therapy, with no significant difference (mid-p exact 95% CI [0.32–1.80], p = 0.82). Only one case of drug resistance occurred with SAT. Conclusion: In patients who underwent surgery for SHI, neither the use of SAT nor SAT duration had any impact on recurrence of SHI regardless of SHI onset or hardware status. The rate of ADR with SAT was comparable to ADR with intravenous antibiotics and the rate of development of drug resistance was low. A randomized control trial is urgently needed to determine the role of SAT and its optimal application in the treatment of SHI.