Does Post-Operative Spine Infection Bacterial Gram Type Affect Surgical Debridement or Antibiotic Duration?

Abstract

Study Design. This is a retrospective cohort study. Objective. The aim was to evaluate differences in readmission rates, number of debridements, and length of antibiotic therapy when comparing bacterial gram type following lumbar spinal fusion infections. Summary of Background Data. Surgical site infections (SSIs) after spinal fusion serve as a significant source of patient morbidity. It remains to be elucidated how bacterial classification of the infecting organism affects the management of postoperative spinal SSI. Methods. Patients who underwent spinal fusion with a subsequent diagnosis of SSI between 2013 and 2019 were retrospectively identified. Patients were grouped based on bacterial infection type (gram-positive, gram-negative, or mixed infections). Poisson regressions analyzed the relationship between the type of bacterial infection and the number of irrigation and debridement (I&D) reoperations, and the duration of intravenous (IV) antibiotic therapy. Significance was set at P<0.05 Results. Of 190 patients, 92 had gram-positive (G+) infections, 57 had gram-negative (G−) infections, and 33 had mixed (M) infections. There was no difference in 30 or 90-day readmissions for infection between groups (both P=0.051). Patients in the M group had longer durations of IV antibiotic treatment (G+: 46.4 vs. G−: 41.0 vs. M: 55.9 d, P=0.002). Regression analysis demonstrated mixed infections were 46% more likely to require a greater number of debridements (P=0.001) and 18% more likely to require an increased duration of IV antibiotic therapy (P<0.001), while gram-negative infections were 10% less likely to require an increased duration of IV antibiotic therapy (P<0.001) when compared with G− infections. Conclusion. Spinal SSI due to a mixed bacterial gram type results in an increased number of debridements and a longer duration of IV antibiotics required to resolve the infection compared with gram-negative or gram-positive infections. Level of Evidence. Level III.

Surgical Site Infection After Primary Spinal Fusion Surgery for Adolescent Idiopathic Scoliosis

“…They can potentially require multiple revisions, including hardware removal, representing a much higher morbidity burden than the "simpler" route of surgical debridement or antibiotic therapy for less severe SSI. 11,[31][32][33][34][35][36] The current study reports obesity and male sex as significant risk factors for SSI after PSF for AIS. Obesity has been a long-established risk factor for SSI in orthopedic spinal arthrodesis, hypothesized to result from increased inflammatory cell activity and pro-inflammatory cytokines released by adipose tissue, longer operative times, and increased tissue trauma.…”

“…The incidence of SSI is positively associated with both BMI and subcutaneous fat thickness overlying the surgical site. 15,28,35,37 Obesity has further been associated with mixed flora infections in patients undergoing spinal fusion, which have a higher risk of relapse after medical management, requiring prolonged antibiotic courses to clear the SSI if medical management is even successful. 35,36 Furthermore, previous literature has shown that obesity is a paradoxical state of malnutrition, where despite a positive energy balance and potentially significant adiposity, obese patients are frequently severely deficient in crucial micronutrients required for proper wound healing.…”

“…15,28,35,37 Obesity has further been associated with mixed flora infections in patients undergoing spinal fusion, which have a higher risk of relapse after medical management, requiring prolonged antibiotic courses to clear the SSI if medical management is even successful. 35,36 Furthermore, previous literature has shown that obesity is a paradoxical state of malnutrition, where despite a positive energy balance and potentially significant adiposity, obese patients are frequently severely deficient in crucial micronutrients required for proper wound healing. 38 In adults undergoing PSF, up to 40% of those with SSI have evidence of clinically significant malnutrition, and malnutrition has been directly linked with a heightened risk of SSI after PSF, as well as significant increases in incision morbidity, length of hospitalization, and 1-year mortality.…”

“…Deeper infections represent more complex complications at a high risk of failing medical management. They can potentially require multiple revisions, including hardware removal, representing a much higher morbidity burden than the “simpler” route of surgical debridement or antibiotic therapy for less severe SSI 11,31–36…”

“…Obesity has been a long-established risk factor for SSI in orthopedic spinal arthrodesis, hypothesized to result from increased inflammatory cell activity and pro-inflammatory cytokines released by adipose tissue, longer operative times, and increased tissue trauma. The incidence of SSI is positively associated with both BMI and subcutaneous fat thickness overlying the surgical site 15,28,35,37. Obesity has further been associated with mixed flora infections in patients undergoing spinal fusion, which have a higher risk of relapse after medical management, requiring prolonged antibiotic courses to clear the SSI if medical management is even successful 35,36.…”