Comparison of bacterial culture results of preoperative synovial fluid and intraoperative specimens in patients with joint infection.

OBJECTIVES The details of relationship between bacterial culture results of preoperative and intraoperative specimens in same patients with native joint septic arthritis (NJSA) and periprosthetic joint infection (PJI) are unknown. This study aims to reveal the difference of culture results of preoperative synovial fluid and intraoperative specimens and evaluate the risk factors for detecting different species intraoperatively from preoperative synovial fluid. METHODS This study included 55 joints diagnosed with 16 NJSA and 39 PJI. Bacterial culture positive rates and identified bacterial species were compared between preoperative synovial fluid and intraoperative tissue/synovial fluid. We also examined the presence or absence of sinus tracts and antimicrobial agents as risk factors in patients with different bacterial species in intraoperative specimens from preoperative synovial fluid. RESULTS The culture positive rates were not significantly different between preoperative synovial fluid and intraoperative specimens. Different bacterium were detected in 10.9% joints by intraoperative tissue and 14.6% joints by intraoperative synovial fluid. The positive rate of sinus tract was significantly higher in patients with different bacterial species (62.5%) than without different bacterial species (12.8%, p < 0.01). Conversely, antimicrobial agent was not significantly difference. CONCLUSION This study demonstrated that different bacterium from preoperative culture results were detected in 10-15% joints by intraoperative specimens in NJSA and PJI. The sinus tract was a risk factor for identifying different bacterial species in the intraoperative specimens. Therefore, in cases of sinus tract, it is necessary to examine multiple specimens of both intraoperative tissue and synovial fluid for increasing the detection rate.