Contribution Of A Multiplex Serological Test For The Preoperative Diagnosis Of Prosthetic Joint Infection: A Prospective Study

Background: Prosthetic joint infection (PJI) is a severe complication of orthopaedic surgery. Preoperative diagnosis, although sometimes difficult, is key to choose the relevant treatment.Methods: We conducted a prospective study aimed at evaluating the diagnostic performance of a multiplex serological test for the pre-operative diagnosis of PJI. Blood samples were collected between 1 July 2016 and 31 July 2017 among patients referred for suspected PJI that occurred at least six weeks prior. Infection diagnosis was confirmed using intraoperative bacteriological cultures during prosthetic exchange.Results: Seventy-one patients were included, with a median age of 73 years (interquartile range [IQR]: 66-81) and 40 (56%) were male. Twenty-six patients had aseptic loosening and 45 patients had PJI. Among the latter, median time since the last surgery was 96 weeks (IQR: 20-324). Intraoperative cultures found Staphylococcus spp, Streptococcus spp or both in 39, 5 and 1 patients, respectively. Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were 81.8, 95.4, 97.3 and 72.4%, respectively, for all patients and 87.5, 93.5, 94.6 and 85.3%, respectively, for staphylococcal infections. Patients with false negative (FN) results had a significantly lower blood lymphocyte count (p = .045).Conclusions: Multiplex serological test performed well among patients with chronic staphylococcal prosthetic infection. This approach could contribute to PJI diagnosis especially in patients for whom the pre-operative analysis of joint fluid is not informative.