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 commonly used prophylactic antibiotics, cefazolin and vancomycin, in preventing iatrogenically introduced Staphylococcus aureus intervertebral disc infections.

OBJECTIVE

This study was performed to assess the efficacy of two prophylactic antibiotics in preventing iatrogenically introduced Staphylococcus aureus intervertebral disc infections.

SUMMARY OF BACKGROUND DATA

Previous studies have had conflicting results regarding the penetration of antibiotics into the nucleus pulposus and their ability to eradicate infection.

METHODS

In this study, 40 adult New Zealand White rabbits underwent inoculation of 10(1) or 10(3) Staphylococcus aureus/ml into 3-6 lumbar intervertebral discs under direct visualization. Either no antibiotics (control groups) or various preoperative and postoperative dosing schedules of cefazolin or vancomycin were given intravenously. Five days after surgery, the discs were harvested and cultured.

RESULTS

All 40 discs inoculated in the control groups became infected. None of the 35 discs inoculated in the cefazolin groups became infected. Infection developed in 23 of 107 discs inoculated in the vancomycin groups. Most notable of these were 17 of 17 positive 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 effectively prevent postoperative discitis. No advantage was found with additional postoperative antibiotics.