MICROBIOLOGICAL PROFILES OF PATIENTS TREATED WITH DEBRIDEMENT, ANTIBIOTICS, AND IMPLANT RETENTION FOR ACUTE PERIPROSTHETIC JOINT INFECTION

Aim Periprosthetic joint infection (PJI) remains a severe complication in arthroplasty, leading to increased morbidity, prolonged hospitalization, and revision surgeries. Débridement, antibiotics, and implant retention (DAIR) is a frequently employed strategy for acute infections to retain the prothesis, whereas two-stage exchange remains the gold standard treatment. The success of DAIR is influenced by various factors. The aim of this study was to evaluate whether the presence of difficult-to-treat (DTT) pathogens and polymicrobial infections significantly influence DAIR outcome. Furthermore, this study investigates the microbiological spectrum, resistance patterns, in acute early-onset and acute late-onset PJI of the hip and knee which were treated with DAIR. Method A total of 116 patients (n=50 knees, n=66 hips) were treated with DAIR during a period of 2018 – 2022 for acute PJI. Acute PJI was defined as symptom duration below three weeks following the criteria defined by Tsukayama and Izakovicova classifications. Patients with lose implant (radiolucent lines > 2mm), macroscopic loosened implant intraoperatively, presence of a sinus tract/fistula, and patients with severe soft tissue impairment were excluded. Demographic data such as BMI, age, and number or prior operations were collected. We differentiated between PJI, polymicrobiological PJI (identification of more than one microorganism from preoperative joint fluid aspiration or intraoperative samples) and difficult-to-treat (DTT) PJI as previously described by Wimmer et al. (2020). Data were compiled and analysed using SPSS Statistics version 28 for Windows (SPSS, Inc., an IBM company, Chicago, IL, USA). Results In this cohort the following pathogen profiles were revealed: Culture-negative cases accounted for 11.3% of infections, while 63.8% were attributed to Gram-positive bacteria, 19.4% to Gram-negative bacteria, and 5% to fungal pathogens. Among the identified microorganisms, coagulase-negative staphylococci (CNS) were the most frequently detected, exhibiting a notable rifampicin resistance rate of 28.7%. Additionally, there was no significant difference revision-free survival between patients with difficult-to-treat (DTT) pathogens and/or polymicrobial PJI compared to those without. Conclusions In this study, CNS emerged as the most frequent pathogen in acute PJI cases, with a notable rifampicin resistance rate of 28.7%. Despite microbiological variations, no significant differences in DAIR outcomes or revision-free implant survival were observed between singular non-DTT PJIs and DTT and/or polymicrobial infections, reinforcing DAIR as a viable treatment strategy for diverse and challenging microbiological profiles. These findings suggest that patient-specific and prosthesis-specific factors may play a crucial role in determining DAIR success, as microbiological characteristics alone did not significantly influence outcomes.