NEXT GENERATION SEQUENCING TEST FOR DIAGNOSING PJI IS NOT AFFECTED BY PREVIOUS ANTIBIOTICS

Introduction Premature administration of antibiotics prior to diagnostic evaluation for periprosthetic joint infection (PJI) is known to compromise the accuracy of standard diagnostic tests, including serum inflammatory markers, synovial fluid analyses, and culture yield. Next generation sequencing (NGS) has emerged as a promising diagnostic modality capable of detecting microbial DNA independent of organism viability. The purpose of this study was to evaluate the effect of premature antibiotic administration on the diagnostic performance of NGS compared with standard serologic and synovial markers as well as traditional culture in patients with MSIS confirmed PJI. Methods A retrospective analysis was performed on 132 patients who underwent revision hip or knee arthroplasty for MSIS confirmed PJI. All patients underwent synovial NGS testing in addition to serum ESR and CRP, synovial WBC count, PMN%, and synovial fluid culture. Forty six percent were treated with an antibiotic prior to diagnostic workup. Patients were categorized into antibiotic and no antibiotic cohorts, and diagnostic sensitivities were compared. Results Premature antibiotics significantly reduced median, synovial WBC count and PMN. Sensitivity was significantly reduced for ESR (75.2% vs 91.5%), CRP (65.4% vs 82.5%), synovial WBC count (70.2% vs 94.4%), and PMN% (75.8% vs 93.5%). Culture yield was markedly impaired, with negative cultures occurring in 36.0% of antibiotic exposed patients compared with 18.3% without antibiotics. NGS demonstrated significantly higher overall sensitivity than culture (96.2% vs 73.5%; p = 0.001) and was unaffected by prior antibiotic treatment (95.1% vs 97.2%). Conclusions Premature antibiotic administration significantly reduces the sensitivity of standard serologic and synovial fluid diagnostic testing for PJI. NGS maintains high diagnostic performance regardless of antibiotic exposure and represents a reliable diagnostic modality in patients who have received premature antibiotics.