THE EFFECT OF PROPHYLACTIC ANTIBIOTICS ON IATROGENIC INTERVERTEBRAL DISC INFECTIONS - A RABBIT MODEL

Study Design. A rabbit model was used to test the efficacy of two comm only used prophylactic antibiotics, cefazolin and vancomycin, in preve nting iatrogenically introduced Staphylococcus aureus intervertebral d isc infections. Objective. This study was performed to assess the effi cacy of two prophylactic antibiotics in preventing iatrogenically intr oduced Staphylococcus aureus intervertebral disc infections. Summary o f Background Data. Previous studies have had conflicting results regar ding the penetration of antibiotics into the nucleus pulposus and thei r ability to eradicate infection. Methods. In this study, 40 adult New Zealand White rabbits underwent inoculation of 10(1) or 10(3) Staphyl ococcus aureus/ml into 3-6 lumbar intervertebral discs under direct vi sualization. Either no antibiotics (control groups) or various preoper ative and postoperative dosing schedules of cefazolin or vancomycin we re given intravenously. Five days after surgery, the discs were harves ted and cultured. Results. All 40 discs inoculated in the control grou ps became infected. None of the 35 discs inoculated in the cefazolin g roups became infected. Infection developed in 23 of 107 discs inoculat ed in the vancomycin groups. Most notable of these were 17 of 17 posit ive cultures in animals given vancomycin 8 hours preoperatively only. Conclusions. Based on these results, it was concluded that intravenous cefazolin or vancomycin given within 1 hour before surgery can effect ively prevent postoperative discitis. No advantage was found with addi tional postoperative antibiotics.