Microbiomes identified after TKA possibly exist in patients’ native knees
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Among 40 patients who underwent total knee arthroplasty for osteoarthritis, results of a prospective cohort study showed next-generation sequencing identified at least one positive organism that was native to the patient’s knee in 12 patients. Furthermore, 4.6 organisms were identified, on average, in patients with positive next-generation sequencing results.
Escherichia coli was the most common organism identified in the native knees of patients studied, according to results of the study by Wayne E. Moschetti, MD, MS, FAAOS, and colleagues, of Lebanon, New Hampshire.
“We sought to understand whether a microbiome exists in the native arthritic knee, similar to other anatomic locations like the gut,” Moschetti told Healio Orthopedics, noting next-generation sequencing (NGS) of DNA is a novel technology that identifies non-host pathogen DNA from a particular sample to diagnosis infection.
In the study, the samples used were taken from patients’ knee synovial fluid aspirations done during TKA, but prior to arthrotomy. The fluid obtained was sent for NGS analysis at MicroGen Diagnostics, as were four separate tissue samples taken from each patient immediately after arthrotomy from the knee’s medial and lateral gutters, suprapatellar pouch and from a femoral swab.
The controls used were sterile water samples from before and after the arthrotomies were performed. These samples were also sent for NGS testing.
Researchers recorded all microbes the NGS analyses identified and noted they represented part of the native knee microbiome.
“Approximately 30% of patients undergoing primary total knee replacement for osteoarthritis had an organism identified by NGS at the time of surgery. This provides an important foundation for future research about the pathophysiology of periprosthetic joint infections as organisms identified may represent the native microbiome rather than pathogenic microbes,” Moschetti said.
Larger studies and longer follow-up are needed to better understand the implications of the effect of the native joint’s microbiome after TKA, the researchers noted in their abstract. – by Susan M. Rapp
Reference:
Moschetti W, et al. ePaper 061. Presented at: American Academy of Orthopaedic Surgeons Annual Meeting; March 24-28, 2020 (meeting canceled).
Disclosures: Moschetti reports no relevant financial disclosures. The study was supported by a resident Orthopaedic Research and Education Foundation grant.
Perspective
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Javad Parvizi, MD, FRCS
Due to a rapid decline in cost, NGS has become a commercially viable technology for identification of infective organisms in difficult to diagnose situations such as implant-related infections. NGS, unlike the other molecular techniques, such as polymerase chain reaction, does not need to be primed to look for a specific organism. The sample with the organisms is processed, and DNA in the sample is then sequenced. The homology between the sequenced DNA is compared with the NIH genome database and the organism(s) identified.
We, as well as other investigators, have been pursuing the use of molecular techniques for identification of infective organisms. There appears to be real promise for the use of NGS in isolation of infective organisms causing orthopedic infections and, in particular, for culture negative infections.
What is interesting and exciting is that Moschetti and colleagues have demonstrated that native arthritic joints of patients undergoing arthroplasty may also contain “microbes” that may be part of the microbiome of that anatomical site. The science of microbiomes has been evolving. We have come to realize that many sites in the body that have traditionally been believed to be “sterile,” do contain microbes. This applies to native human joints. Prior studies have shown a distinct microbiome for the shoulder joint and other areas in the body also.
The current study provides unique perspectives on how the native arthritic joint may consist of microbes, many of which could become a pathogen, given the chance.
We are starting to explore an exciting and challenging field in medicine. Our current thinking on how orthopedic infections are caused may come under scrutiny as further evidence on microbiomes and dysbiosis emerges.
Rothman Institute at Thomas Jefferson University
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