To explore the value of next generation sequencing (NGS) in diagnosis of Periprosthetic Joint Infection (PJI) by comparing with bacterial culture and serum biomarker.

A total of 35 patients (35 cases) who underwent joint revision surgery in department of joint surgery of the Liaocheng People's Hospital from July 2017 to December 2019 were selected. Inclusion criteria: infection or aseptic loosening after prosthesis replacement. Exclusion criteria: the patients whose initial synovial fluid cannot be collected, samples obtained by intra-articular injection of normal saline and patients with infected lesions in other parts. According to the diagnostic criteria of the Muscular Skeletal Infection Society (MSIS), 15 patients were included in the infection group and 20 patients were included in the non-infection group. The patients in both groups routinely received examination of erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin (PCT), interleukin 6 (IL-6), and D-Dimer preoperatively. All the patients were given a joint puncture preoperatively. The synovial fluid was used to detect white blood cell count, white blood cell classification, bacterial culture, and NGS. The area under the curve (AUC) of the receiver operating characteristic curve (ROC) of the ESR, CRP, PCT, IL-6, and D-Dimer was calculated. The diagnostic accuracy, sensitivity, and specificity of NGS, bacterial culture, and various serological markers were also calculated.

Nineteen cases of hip joints (54.3%) and 16 cases of knee joints (45.7%) were included. There were 21 males (60.0%) and 14 females (40.0%), age was 67.0(62.0, 74.0) years. Fourteen cases were positive for NGS (93.3%) and seven cases were positive for bacterial culture (46.7%) in the infection group. NGS results were negative in 18 cases (90.0%) in the non-infected group. The AUCs of ESR and D-Dimer were 0.667 and 0.572, respectively (both P values>0.05). The AUC of CRP, IL-6 and PCT were 0.827, 0.767 and 0.808, respectively (all P<0.01). The accuracy of NGS, bacterial culture, CRP, IL-6 and PCT were 0.91, 0.74, 0.77, 0.74 and 0.83, respectively. When comparing NGS with CRP, IL-6, PCT, and bacterial culture, the difference in overall test results were statistically significant (P<0.01). NGS compared with CRP, IL-6, PCT and bacterial culture, the sensitivity of NGS was higher (P<0.05). Compared with CRP, the specificity of NGS was higher (P<0.05). Compared with IL-6, PCT and bacterial culture, the specificity of NGS was not statistically significant (P>0.05).

NGS has higher accuracy and sensitivity than bacterial culture and commonly used serological markers, and has greater value in diagnosis of PJI.