Methods: Synovial fluid was collected from 112 failed TKAs [74 PJI and 38 aseptic implant failure (AF)] via preoperative arthrocentesis. Cell count and differential, standardized culture and DNA-based metagenomic shotgun sequencing were performed. Human DNA was depleted using the MolYsis basic kit prior to DNA extraction, whole genome amplification, and sequencing. Taxonomic assignment of reads and pathogen identification was achieved using a pipeline incorporating k-mer- and marker gene-based classification software. A scheme for analysis and filtration of false-positives was created and applied, incorporating cutoffs for the number of reads, quality scores, and coverage across a reference genome. Patients were classified as having PJI using the IDSA criteria and expert review. Analyses were recorded as percent agreement, with 95% confidence intervals (CI), of metagenomics to SF culture.
Results: Metagenomic analysis identified the known pathogen in 54 (90%) (CI, 79.5%-96.2%) of the 60 culture-positive PJIs analyzed and one (2%) (CI, 0.0%-8.9%) potential polymicrobial infection not detected by culture. For the 14 culture-negative PJIs tested, metagenomics showed 79% (CI, 49.2%-95.3%) agreement for negative findings; potential pathogens were identified in three (21%) (CI, 4.7%-50.8%) culture-negative PJI cases, with one being polymicrobial. Of the 37 culture-negative AF cases, metagenomics showed 97% (CI, 85.8%-99.9%) agreement with negative culture and identified one (3%) (CI, 0.0%-14.2%) potential pathogen. For the one culture-positive AF case, metagenomic results were negative, suggesting possible culture contamination.
Conclusion: Metagenomic shotgun sequencing performed on SF can be used to diagnose PJI and may be particularly useful for culture-negative PJI.
P. Jeraldo, None
K. Greenwood-Quaintance, None
A. D. Hanssen, None
M. Abdel, None
N. Chia, None
J. Yao, None
A. Tande, None
J. Mandrekar, None
R. Patel, ASM: Board Member , None
CD Diagnostics, BioFire, Curetis, Merck, Hutchison Biofilm Medical Solutions, Accelerate Diagnostics, Allergan, and The Medicines Company: Grant Investigator , Grant recipient
Curetis: Consultant , Monies paid to my employer
A patent on Bordetella pertussis/parapertussis PCR issued, a patent on a device/method for sonication with royalties paid by Samsung to Mayo Clinic, and a patent on an anti-biofilm substance issued: Patents , Patents, any money is paid to my employer
Actelion: DSMB , Money paid to my employer
ASM and IDSA: Editor's stipends , Editor's stipends
NBME, Up-to-Date and the Infectious Diseases Board Review Course: NBME, Up-to-Date and the Infectious Diseases Board Review Course , Honoraria
Roche, ASM, and IDSA: Travel reimbursement , Travel reimbursement