Microbiological diagnostic criteria of infectious inflammatory complications after total knee replacement in the aspect of periprosthetic joint infection (PJI) pathogenesis

Background. The system of accurate microbiological diagnostics of implant-associated inflammation for timely identification of infectious inflammatory complications after total joint replacement and distinguishing between peritransplant and aseptic infection has not been yet defined which is associated with the peculiarity of pathogenesis of infection process. The aim of the study is to define valuable microbiological diagnostic criteria for implant-associated infection and to estimate diagnostic value of various clinical specimens with the account to pathogenetic features of infectious complications after primary total knee replacement. Material and methods. We analyzed 412 specimens of various clinical origin obtained from 182 patients with deep PJI after primary total knee replacement treated at the Research Institute of Traumatology, Orthopedics and Neurosurgery of Razumovsky Saratov State Medical University in 2014-2018. Analysis was both retro- and prospectively. Results and discussion. Studies of the discharge fistula, superficial wounds and aspirate from the joint cavity are not sufficiently informative methods of diagnosis of implant-associated infection. Optimized microbiological algorithm included prolonged culture time, the complex of 3-5 tissue bioptates cultures and implant ultrasonic treatment which allowed obtaining more valuable results for PJI diagnostics. Tissue bioptates and lavage fluid specimens’ tests were the most sensitive methods for PJI diagnostics with sensitivity of 81% and 95% and specificity of 96% and 97% respectively, especially in case of coagulase-negative Staphylococcus and Gram-negative bacteria frequently appearing in the biofilm form at PJI. Conclusions. Complex assessment of obtained results and optimization of microbiological methods allow obtaining sufficient diagnostic accuracy of PJI.