Locally Used Antibiotics for Spinal Infection Prophylaxis and Their Effects on Epidural Fibrosis: an Experimental Laminectomy Study in Rats Using Rifamycin and Gentamycin.

The study aims to assess the effects of antibiotics (ABs), which are typically used in spinal infection prophylaxis, on the formation of epidural fibrosis (EF). Specifically, we investigated the effect of rifamycin and gentamycin on EF formation in laminectomized rats. Thirty-two rats were randomly and equally divided into four groups as follows: laminectomy and physiological saline (0.9% NaCl) solution (control); laminectomy and rifamycin; laminectomy and gentamicin; and laminectomy and a mixture of rifamycin and gentamicin. Laminectomy was performed on L1 and L2 vertebrae in all rats. One month after spinal surgery, spinal tissue samples surrounding the laminectomy were cut with a microtome and stained with hematoxylin-eosin and Masson's trichrome. The histopathological analysis included examining the extent of EF, fibroblast cell density, and cartilage and bone regeneration. Statistical analysis was performed using the IBM SPSS Statistics 22 program (SPSS IBM, Turkey). A value of p < 0.05 was considered statistically significant. EF value differences between the AB treatment groups and the control group were statistically significant (p = 0.030). Specifically, binary comparisons indicated that the EF value was significantly higher in the rifamycin group than that in the control group (p = 0.003; p < 0.05). Our study suggests that locally applied ABs, especially rifamycin, should be diluted before administration to the epidural space.