Does the Timing of Antibiotic Administration Affect Culture Results During Resection for Periprosthetic Joint Infection?

INTRODUCTION: When a patient presents on antibiotics for a suspected periprosthetic joint infection (PJI), antibiotics are often withheld prior to diagnostic aspiration. Failure to withhold antibiotics may compromise culture sensitivity. Although recent studies suggest preoperative antibiotics may not affect culture results, the small sample size limits the reliability of these findings. Since treatment failure often involves organisms different than those detected at resection, timing of antibiotic delivery becomes critical. We investigated the difference in culture results and infection control when antibiotics were administered prior to resection versus when antibiotics were withheld.

METHODS: Review of patients undergoing staged treatment for PJI was performed. Inclusion required accessible preoperative aspiration and intraoperative cultures. Patients were grouped by timing of antibiotic administration- before or after obtaining intraoperative cultures. Organisms cultured on preoperative aspiration and those cultured at resection were compared. Patients experiencing reimplantation failure were identified, and causative organism was documented. Of the 169 procedures that met inclusion criteria (92 knees, 77 hips), 29.0% (49 of 169) received antibiotics prior to intraoperative cultures (21 knees, 28 hips) while 71% (120 of 169) did not (71 knees, 49 hips).

RESULTS: Among patients receiving preoperative antibiotics, the discordance rate (defined as mismatch between preoperative aspiration and resection cultures) was 42.9% (nine of 21) for knees and 39.3% (11 of 28) for hips. Among patients having antibiotics withheld until resection cultures were taken, the discordance rate was lower- 29.6% (21 of 71) for knees and 24.5% (12 of 49) for hips (P = 0.091). The overall success rate was significantly lower in the group receiving antibiotics compared to the group where antibiotics were withheld (79.6 versus 90% P = 0.014).

CONCLUSIONS: These findings suggest that withholding antibiotics until cultures are obtained may reduce culture discordance and reimplantation failure.