Spondylodiscitis after lumbar microdiscectomy: effectiveness of two protocols of intraoperative antibiotic prophylaxis in 1167 cases

The role of antibiotic prophylaxis in preventing postoperative lumbar spondylodiscitis is still controversial in medical, ethical, economic, and legal terms. The aim of this retrospective study was to evaluate the efficacy of two intraoperative antibiotic prophylaxis protocols in a large series of lumbar microdiscectomies performed in two different neurosurgical centres. We reviewed the outcome of 1167 patients operated on for a lumbar disc herniation with microsurgical technique, in order to detect the incidence of postoperative spondylodiscitis. Group A included 450 patients operated on in a 3-year period in the Neurosurgical Division of the University Hospital of Ancona; group P consisted of 717 patients operated on in a 4-year period in the Neurosurgical Division of the Sandro Pertini Hospital of Rome. In both groups intraoperative antibiotics for prophylaxis were administered, whereas postoperative prophylaxis was not performed. Protocol of group A: single intravenous dose of cefazoline 1 g at induction of general anesthesia and generous washing with saline solution and irrigation with a solution containing rifamicin at the end of microsurgical procedure. Protocol of group P: single-dose of intravenous ampicillin 1000 mg and sulbactam 500 mg at induction of anesthesia and generous irrigation with saline solution at the end of microsurgical procedure. A diagnosis of postoperative spondylodiscitis was made in three out of 450 patients in group A (0.67%) and in 5 out of 717 patients in group P (0.69%). In all cases, treatment consisted of rigid thoraco-lumbar orthesis and 4- to 6-week administration of amoxicillin/clavulanate compound (500/125 mg). The low incidence of postoperative spondylodiscitis obtained with both our protocols seems to confirm that intraoperative antibiotic prophylaxis is associated with the same rate of discitis of prolonged prophylaxis usually still adopted in many centres, but is more advantageous both in terms of welfare and comfort for patients and in economic terms. However, at the moment it is not possible identify the ideal antibiotic for this purpose. It seems to be reasonable to search for the solution through large multicenter prospective studies.