Appropriateness of antibiotic selection and use in laminectomy and microdiskectomy

The selection and timing of antibiotic prophylaxis in spinal surgery patients were studied. All laminectomy and microdiskectomy cases in which surgical-wound infection had developed within 60 days of surgery during 1990 at a medical center were retrospectively reviewed because of the high rate of postoperative wound infection for these procedures at the institution. The evaluation covered drug selection, the timing of antibiotic administration relative to the surgical incision, culture and susceptibility test results, and the length of the surgical procedure. Surgical-wound infection was found to have developed in 22 (7%) of the 315 patients who underwent laminectomy or microdiskectomy. There was no apparent difference between the infected group and a matched, uninfected control group in either the antibiotic selected or the number of doses given. On the basis of the organisms isolated from the wounds and susceptibility test results, the selection of cefazolin as the antibiotic was appropriate in 17 of the 22 infected patients. However, compared with the control group, the infected group had a significantly higher percentage of patients in whom antibiotics had been given more than two hours before the time of the surgical incision. The policy on administering prophylactic antibiotics was modified; current guidelines include giving the first dose of cefazolin upon the induction of anesthesia and follow-up administration in three hours if the incision has not been closed by then. The selection of a prophylactic antibiotic for spinal surgery patients was appropriate, but the timing of drug administration was usually not optimal.