Sequencing of Circulating Microbial Cell-Free DNA Can Identify Pathogens in Periprosthetic Joint Infections

Area of Science:

• Orthopedics
• Infectious Diseases
• Molecular Diagnostics

Background:

• Periprosthetic joint infections (PJIs) affect a significant portion of the over 1 million annual joint replacement surgeries.
• Standard culture methods for PJIs have limitations, failing to identify organisms in 10-20% of cases and requiring invasive procedures.
• Cell-free DNA (cfDNA) in blood is hypothesized as a potential biomarker for microbial detection in PJIs.

Purpose of the Study:

• To evaluate the accuracy of next-generation sequencing of microbial cell-free DNA (cfDNA) from peripheral blood for identifying pathogens in patients with PJI.
• To compare the diagnostic yield of cfDNA sequencing with traditional intraoperative cultures.
• To assess the potential of cfDNA sequencing to improve pathogen detection rates and reduce time-to-speciation.

Main Methods:

• A prospective observational study enrolled 53 adults with confirmed hip or knee PJIs.
• Peripheral blood was collected preoperatively for plasma cfDNA extraction and next-generation sequencing.
• Results were compared against standard-of-care intraoperative tissue and synovial fluid cultures.

Main Results:

• Microbial cfDNA sequencing identified pathogens in 35 cases, including 4 of 7 culture-negative PJIs, increasing overall detection from 87% to 94% when used adjunctively.
• The median time to species identification was 3 days shorter for cases with genus-only culture results.
• cfDNA sequencing detected additional microorganisms in 14 cases and showed reduced pathogen levels postoperatively.

Conclusions:

• Microbial cfDNA circulating in peripheral blood can be effectively sequenced for PJI pathogen identification.
• This noninvasive blood-based cfDNA sequencing holds promise as an adjunct to cultures, improving diagnostic accuracy and speed.
• Future applications may include monitoring infection clearance during treatment.