Response to the letter to the editor: Impact of abscess type on outcomes following posterior fixation for thoracolumbar pyogenic spondylitis: a multicenter retrospective cohort study

Dear Editor,

We thank the authors for their thoughtful and constructive comments on our study [1], “Impact of abscess type on outcomes following posterior fixation for thoracolumbar pyogenic spondylitis: a multicenter retrospective cohort study.” We greatly appreciate their careful interpretation of our findings and their proposal to extend abscess classification toward a more treatment- oriented framework.

We agree that surgical timing is an important factor when interpreting the association between abscess type and intravenous antibiotic duration. As the authors appropriately pointed out, the differences in total intravenous antibiotic duration in our study were mainly attributable to the preoperative period, whereas differences in postoperative intravenous duration were relatively small. Thus, our findings should not be interpreted as indicating that abscess location itself directly determines the response to posterior fixation or the required duration of antimicrobial treatment. Surgical timing is an important component of the management of pyogenic spinal infection, particularly in patients with neurological compromise, spinal instability, or failure of medical treatment [2,3].

Interestingly, we had the same clinical question while interpreting our findings: whether differences in antibiotic treatment duration reflect abscess location itself or differences in the timing of surgical intervention. This question has led us to further investigate the relationship between surgical timing and antibiotic treatment duration in patients with pyogenic spondylitis treated with posterior fixation. We are therefore very pleased that the authors independently recognized and highlighted the same important clinical issue. Although our original study was not designed to determine the independent effect of surgical timing, we agree that this variable should be considered when interpreting differences in treatment duration among abscess types.

We also agree with the authors’ suggestion to use surgery as time zero and evaluate postoperative response separately. Postoperative intravenous antibiotic duration, total antimicrobial duration including oral therapy, inflammatory marker response, bacteremia, infection-related reoperation, and readmission may provide a more comprehensive assessment of treatment response. Current evidence supports highly bioavailable oral antimicrobial therapy in appropriately selected patients with bone and joint infections, suggesting that intravenous duration alone may not fully represent the overall antimicrobial burden [2,4].

We also agree that anatomical location alone may not fully characterize the clinical significance of an abscess. Neurological status, canal compromise, feasibility of percutaneous drainage, and concomitant source-control procedures may influence treatment decisions. Incorporating these factors may help distinguish the effect of posterior stabilization from that of additional source-control procedures.

Our study demonstrated that different abscess locations are associated with distinct clinical characteristics and treatment courses, but abscess location should be regarded as one component of a broader clinical phenotype rather than an isolated determinant of treatment response. We agree that integrating abscess phenotype, surgical timing, postoperative response, and source-control strategy represents an important next step toward a more clinically useful treatment framework for pyogenic spondylitis.

We sincerely thank the authors for their insightful comments and for sharing our interest in this important clinical question.