Next generation sequencing identifies an increased diversity of microbes in post lavage specimens in infected TKA using a biofilm disrupting irrigant

Background: Periprosthetic joint infection (PJI) is a devastating complication of joint arthroplasty. In chronic PJI, a biofilm envelops the surface of implants, which contains microbiota within an extra-microbial polymeric matrix (EMPM). Microbial identification is paramount for effective treatment. In this study, we use a multi-modal, EMPM disrupting, neoadjuvant irrigant and compare the microbiota detected pre-lavage to post-lavage by two techniques: culture and Next Generation Sequencing (NGS). We suspect more organisms to be identified after applying an EMPM disrupting irrigant.

Methods: A multicenter, prospective study was conducted on 38 patients with known Total Knee Arthroplasty PJI. At initial arthrotomy, synovial fluid was obtained and analyzed for quantitative cultures and microbial NGS. Joint was then irrigated with Bactisure Lavage followed by Normal Saline. Post-lavage samples were similarly obtained and analyzed.

Results: In pre-lavage samples for cultures, 55.3% of samples were positive, identifying 11 unique organisms. In post-lavage samples for cultures, 13.2% of samples were positive, identifying 5 unique organisms. In pre-lavage samples for NGS, 79% were DNA signal positive, identifying 126 unique organisms. In post-lavage samples for NGS, 74% of samples were DNA signal positive, identifying 177 unique organisms. Moreover, 135/177 of these organisms were not identified pre-lavage.

Conclusion: In this pre-to-post irrigant study, culture showed a decrease in the number of identifiable organisms post-lavage. In contrast NGS revealed an increase in the number of identifiable organisms post-lavage. Furthermore, NGS identified 135 additional organisms, not detected pre-lavage. This suggests an increased diversity of microbes may exist within EMPM, which are not cultivable.