Medicinal, Psychological, and Health Research Journal (MPHRJ) 3092-7560 2 5 2026 09 23 Systematic Review of Bacterial Pathogens Associated with Prosthetic Joint Infection After Total Knee Arthroplasty 400 408 246101 10.22034/mphrj.2026.587090.1105 EN Alireza Aghili Assistant Professor of Orthopaedics, Department of Orthopedics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran Sina Najafi Department of Infectious Disease, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran 0000-0002-1357-7795 Journal Article 2026 03 28 Introduction: Prosthetic joint infection (PJI) remains one of the most serious complications following total knee arthroplasty, leading to substantial morbidity, repeated surgical procedures, and increased healthcare burden. These infections are primarily driven by bacterial colonization and biofilm formation on implant surfaces. Given the variability in reported causative microorganisms, the aim of this study was to systematically review the literature to identify the bacterial pathogens most commonly associated with PJI after total knee arthroplasty.<br><br>Material and methods: This systematic review followed PRISMA guidelines to identify bacterial pathogens associated with prosthetic joint infection after total knee arthroplasty. Studies were retrieved from PubMed, Web of Science, ScienceDirect, and Google Scholar using structured keywords. Two reviewers independently screened articles, and methodological quality of eligible observational studies was assessed using the Joanna Briggs Institute appraisal tools.<br><br>Results: Across four published case reports (n = 4), Ruminococcus/Mediterraneibacter gnavus was implicated in prosthetic joint infection (25%), deep surgical site infection (25%), bacteraemia (25%), and septic arthritis (25%), predominantly in elderly or immunocompromised patients. Identification relied on MALDI-TOF and/or 16S rRNA sequencing in all cases (100%), and favorable clinical outcomes were achieved with combined surgical management and targeted antibiotic therapy in the majority of reported infections.<br><br>Conclusion: Mediterraneibacter gnavus should be recognized as a rare but clinically significant opportunistic pathogen capable of causing orthopedic and systemic infections. Accurate diagnosis depends on advanced microbiological techniques, and outcomes appear favorable with timely surgical intervention and targeted antimicrobial therapy. Increased awareness may facilitate earlier detection and appropriate management. https://www.mphrj.com/article_246101_a2c559b74e215dbbb11737f6bfa12dfd.pdf