Letter to the editor: ‘Vancomycin Antibiotic Prophylaxis Compared to Cefazolin Increases Risk of Surgical Site Infection Following Spine Surgery’ by Brandon J. Herrington et al

To the Editor,

Recently, we had the opportunity to examine the article entitled “Vancomycin Antibiotic Prophylaxis Compared to Cefazolin Increases Risk of Surgical Site Infection Following Spine Surgery” by Brandon J. Herrington et al. ¹ This study undertakes a comprehensive analysis of a randomized controlled trial, investigating the impact of vancomycin and cefazolin as surgical antibiotic prophylaxis (SAP) on the incidence of surgical site infections (SSI) in spinal surgeries. The authors’ findings indicate that, in the context of open posterior spinal fusion surgery, the use of vancomycin SAP is associated with a higher risk of infection compared to cefazolin SAP. While we commend the authors for their valuable contribution to the field, several aspects of the study warrant further investigation.

Firstly, the authors administered vancomycin to patients citing an ‘allergic reaction to β-lactams’ as the rationale. However, they did not evaluate whether these patients were colonized with methicillin-resistant Staphylococcus aureus (MRSA). Previous studies have demonstrated that prophylactic administration of vancomycin to patients who test positive for MRSA prior to surgery significantly reduces the overall postoperative infection rate, including MRSA-related infections. ² Although the authors referenced MRSA and the use of vancomycin, they did not ascertain the MRSA colonization status of the patients involved in this study. This oversight could result in some patients, who were inherently more susceptible to infection, not receiving appropriate targeted prophylaxis, while others with a lower risk were assigned to the vancomycin group solely due to β-lactam allergies, thereby receiving unnecessary broad-spectrum prophylaxis. This may introduce potential bias in the interpretation of vancomycin’s effects within this experimental study.

Secondly, the localized application of vancomycin powder can achieve elevated concentrations of antibacterial agents at the surgical site, thereby diminishing the incidence of surgical site infections. For example, research conducted by Haimoto et al ³ demonstrates that, in addition to systemic prophylactic antibiotic administration, the localized application of vancomycin powder can mitigate the risk of adverse drug reactions. Their findings indicate a significant reduction in the incidence of SSIs among patients treated with vancomycin powder, with no reported drug-related complications. However, the authors’ research only focused on the intravenous administration route and did not consider the local application of vancomycin powder in wounds.

In addition, this experiment lacks pharmacokinetic data for the appropriate therapeutic doses of 2 antibiotics and guidance on effective concentrations at the surgical site, making it hard to ensure all patients achieve effective drug exposure. Bue et al’s animal study used microdialysis to track vancomycin levels in intervertebral discs, vertebral cancellous bone, and subcutaneous fat, revealing insufficient drug penetration and delayed concentration in spinal tissues. They concluded that a single intravenous dose might not quickly establish effective antibacterial levels in all patients. ⁴ If the author could comprehensively monitor drug concentrations in the bone and intervertebral discs, it might improve the accuracy of the experiment by reducing errors caused by insufficiently effective drug levels.

Finally, we would like to express our gratitude to the authors for conducting the research on the use of antibiotics at the surgical site after patients’ surgeries. The study clearly demonstrated that vancomycin SAP increases the risk of spinal surgery SSI compared to cefazolin, providing new guidance for the prevention of SSI after spinal surgery and an important basis for clinical antibiotic selection.