Microbiological profile of surgical site infections in spine surgery: a retrospective analysis in an orthopedic hospital.

Abstract

Introduction:
Surgical site infections (SSIs) in orthopedics represent a high-impact public health complication with significant clinical, psychosocial, and economic consequences. Particularly in spine surgery, SSIs can lead to chronic pain, multiple reoperations, and prolonged hospital stays. Timely and accurate diagnosis, along with identification of the etiologic agent, is essential to establish appropriate treatment and reduce morbidity and mortality.

Objective:
To describe the microbiological profile of patients diagnosed with surgical site infection in the spine service of an orthopedic hospital from 2022 to 2023.

Methodology:
A descriptive, cross-sectional, and retrospective study was conducted at the Orthopedic Hospital, using the institutional database corresponding to the period from January 1, 2022, to December 31, 2023. Patients diagnosed with SSIs according to ICD-10 codes, specifically those related to spinal procedures, were included. Descriptive statistical analysis was applied, including frequencies, measures of central tendency, and standard deviations.

Results:
A total of 277 patients with a diagnosis of nosocomial infection were identified, with a mean age of 60.02 years and a slight female predominance (50.1%). Of these, 89.16% (n=246) corresponded to surgical site infections, and among those, 19.51% (n=48) originated in the spine service. The most frequently associated procedure was lumbar fusion (12.19%), followed by discectomy (7.31%). Regarding diagnostic methods, biopsy culture was used in 6.5% of cases, swabbing in 8.9%, and in 4.06% the type of culture was not specified. The most frequently isolated microorganism was Escherichia coli (16.32%), followed by Enterococcus (16.32%) and Staphylococcus epidermidis (10.41%). Contrary to existing literature, Staphylococcus aureus was isolated in only 4.16% of cases. Negative cultures were reported in 14.58% of samples, a percentage that also corresponded to inadequate samples. Additionally, in three cases (6.25%), microorganisms producing extended-spectrum beta-lactamases (ESBL) were identified.

Conclusion:
Spinal surgical site infections represented 19.51% of the total SSIs detected in the hospital during the studied period, being more prevalent after lumbar fusion procedures. Unlike what is reported in the literature, the most common causative agent was E. coli, not S. aureus. The high proportion of cultures without bacterial growth (12.5%) suggests a need to improve sampling techniques and consider the possibility of false negatives, which may impact the adequate initiation of antimicrobial treatments.