Background and PurposeOptimal antibiotic prophylaxis is crucial to prevent postoperative infection in spinal surgery. Sufficient time above the minimal inhibitory concentration (fT > MIC) for relevant bacteria in target tissues is required for cefuroxime. We assessed cefuroxime concentrations and fT > MIC of 4 μg·ml−1 for Staphylococcus aureus in the intrathecal (spinal cord and cerebrospinal fluid, CSF) and extrathecal (epidural space) compartments of the lumbar spine.Experimental ApproachEight female pigs were anaesthetized and laminectomized at L3–L4. Microdialysis catheters were placed for sampling in the spinal cord, CSF, and epidural space. A single dose of 1500 mg cefuroxime was administered intravenously over 10 min. Microdialysates and plasma were obtained continuously during 8 h. Cefuroxime concentrations were determined by ultra‐high‐performance liquid chromatography.Key ResultsMean fT > MIC (4 μg·ml−1) was 58 min in the spinal cord, 0 min in the CSF, 115 min in the epidural space, and 123 min in plasma. Tissue penetration was 32% in the spinal cord, 7% in the CSF, and 63% in the epidural space.Conclusion and ImplicationsfT > MIC (4 μg·ml−1) and tissue penetration for cefuroxime were lower in the intrathecal compartments (spinal cord and CSF) than in the extrathecal compartment (epidural space) and plasma, suggesting a significant effect of the blood–brain barrier. In terms of fT > MIC, a single dose of 1500 mg cefuroxime seems inadequate to prevent intrathecal infections related to spinal surgery for bacteria presenting with a MIC target of 4 μg· ml−1 or above.