Does intraoperative antiseptic solution soaking reduce microbial contamination in spine surgery? A randomized controlled trial

Abstract

Background context: Surgical site infections (SSIs) are a significant complication in spine surgery, particularly in instrumented procedures, leading to increased morbidity and healthcare costs. Despite standard preoperative disinfection protocols, bacterial contamination remains prevalent. Strategies such as intraoperative antiseptic irrigation have been explored to mitigate contamination, yet the comparative efficacy of different antiseptic solutions remains unclear.

Purpose: This study aimed to evaluate the effectiveness of intraoperative antiseptic solution soaking with normal saline (NS), povidone-iodine (PVP-I), and chlorhexidine gluconate (CHG) in reducing bacterial contamination in lumbar instrumented fusion surgery.

Study design/setting: A single-center, single-blinded, randomized controlled trial was conducted at a tertiary medical center in Taiwan.

Patient sample: A total of 105 patients undergoing posterior lumbar interbody fusion surgery were enrolled and randomly assigned to three groups: NS (n=35), PVP-I (n=35), or CHG (n=35). Patients with prior lumbar procedures, known allergies to antiseptics, previous spinal infections, trauma, or tumors were excluded.

Outcome measures: The primary outcome was the reduction in bacterial contamination, assessed via intraoperative cultures from three sites-superficial tissues, deep tissues, and implant surfaces-before and after antiseptic irrigation. Secondary outcomes included the incidence of postoperative SSIs and clinical complications over a 6-month follow-up period.

Methods: Patients were randomized into three groups, each receiving a 3-minute soak with the assigned antiseptic solution before wound closure, followed by normal saline irrigation. Swab samples were collected pre- and postirrigation for bacterial culture and 16S rRNA PCR analysis. Statistical analysis was performed using logistic regression and Bonferroni correction for multiple comparisons.

Results: Among 105 patients, preirrigation bacterial culture positivity rates were 49.5% in superficial tissues, 31.4% in deep tissues, and 32.4% on implants. Postirrigation, NS showed no significant bacterial reduction, while PVP-I reduced superficial contamination (55.0%, p=.015) but no significant effect in deeper tissues and implants. CHG showed the greatest bacterial reduction, significantly outperforming NS (OR: 0.06, 95% CI: 0.01-0.54, p=.011) and PVP-I (OR: 0.06, 95% CI: 0.01-0.56, p=.012) on implant surfaces. Despite these differences in culture rate, SSI rates remained low and comparable among groups (p=.72), with no reported antiseptic-related complications.

Conclusion: This study confirms that bacterial contamination remains high despite standard preoperative disinfection in lumbar fusion surgery. Among the tested antiseptic solutions, CHG demonstrated superior efficacy in reducing bacterial residues, particularly on implant surfaces. These findings support CHG as a promising antiseptic for intraoperative irrigation in spine surgery. Further multicenter studies are needed to validate its impact on reducing SSIs and improving long-term outcomes.

Level of evidence: Level II.

Keywords: Antiseptic irrigation; Chlorhexidine gluconate (CHG); Implant infection; Spinal surgery; Surgical site infection (SSI).