Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study

Abstract

Objectives: The objective of this study was to develop a test for the rapid (within 25 minutes) intraoperative detection of bacteria from synovial fluid to diagnose periprosthetic joint infection (PJI).

Methods: The 16s rDNA test combines a polymerase chain reaction (PCR) for amplification of 16s rDNA with a lateral flow immunoassay in one fully automated system. The synovial fluid of 77 patients undergoing joint aspiration or primary or revision total hip or knee surgery was prospectively collected. The cohort was divided into a proof-of-principle cohort (n = 17) and a validation cohort (n = 60). Using the proof-of-principle cohort, an optimal cut-off for the discrimination between PJI and non-PJI samples was determined. PJI was defined as detection of the same bacterial species in a minimum of two microbiological samples, positive histology, and presence of a sinus tract or intra-articular pus.

Results: The 16s rDNA test proved to be very robust and was able to provide a result in 97% of all samples within 25 minutes. The 16s rDNA test was able to diagnose PJI with a sensitivity of 87.5% and 82%, and a specificity of 100% and 89%, in the proof-of-principle and validation cohorts, respectively. The microbiological culture of synovial fluid achieved a sensitivity of 80% and a specificity of 93% in the validation cohort.

Conclusion: The 16s rDNA test offers reliable intraoperative detection of all bacterial species within 25 minutes with a sensitivity and specificity comparable with those of conventional microbiological culture of synovial fluid for the detection of PJI. The 16s rDNA test performance is independent of possible blood contamination, culture time and bacterial species.Cite this article: V. Janz, J. Schoon, C. Morgenstern, B. Preininger, S. Reinke, G. Duda, A. Breitbach, C. F. Perka, S. Geissler. Rapid detection of periprosthetic joint infection using a combination of 16s rDNA polymerase chain reaction and lateral flow immunoassay: A Pilot Study. Bone Joint Res 2018;7:12-19. DOI: 10.1302/2046-3758.71.BJR-2017-0103.R2.

Keywords: 16s rDNA; Immunoassay; Lateral flow; Periprosthetic joint infection; Polymerase chain reaction; Rapid detection.

General workflow of the 16s rDNA test: a) chronological test principle, with polymerase chain reaction (PCR) followed by subsequent detection of the specific PCR products by lateral flow immunoassay; b) the results are displayed as one test band (T, detection of 16s rDNA); and c) a control band (C), confirming the correct function of assay).

General test performance using the proof-of-principle cohort: a) receiver operating characteristic (ROC) curve for the 16s rDNA test based on the calculated ratio between test and control band to determine the optimal cut-off value to differentiate between periprosthetic joint infection (PJI) and non-PJI samples; and b) box-whisker plot displaying the performance of the 16s rDNA test to differentiate between PJI (n = 8) and non-PJI (n = 9) samples in the proof-of-principle cohort. Dashed lines indicate the optimal cut-off as determined by previous ROC analysis. The Mann–Whitney U test was used to obtain p-values. AUC, area under the curve; CI, confidence interval; AU, assay unit.

Validation of the test performance using the validation cohort: a) receiver operating characteristic (ROC) curve for the 16s rDNA test (ratio between test and control band on the test strip) to differentiate between periprosthetic joint infection (PJI) and non-PJI samples in the validation cohort; and b) box-whisker plot displaying the performance of the 16s rDNA test to differentiate between PJI (n = 23) and non-PJI (n = 37) samples in the validation cohort. Dashed lines indicate the predefined cut-off as determined using the proof-of-principle cohort. The Mann–Whitney U test was used to obtain p-values. AUC, area under the curve; CI, confidence interval; AU, assay unit.