RIFAMPICIN-FLUOROQUINOLONE VERSUS RIFAMPICIN-MINOCYCLINE IN PROSTHETIC JOINT INFECTION: A RETROSPECTIVE COHORT STUDY

Introduction and Aim Periprosthetic joint infections (PJI) remain a challenging complication in orthopedic surgery, requiring combined surgical and antibiotic management. Among all PJIs, around 75% are caused by Gram-positive bacteria, where the most widely used antibiofilm oral antibiotic regimen following surgical intervention consists of a rifampicin/quinolone-based regimen. Still, the optimal alternative companion antibiotic in case of resistance or intolerance remains unclear. This study aims to analyze the treatment success rate with rifampicin/quinolone or rifampicin/minocycline for PJI. Materials and Methods A retrospective registry-based study was conducted at a teaching orthopedic hospital, including patients treated between 2007 and 2025 for PJI of the hip or knee joint. All patients underwent initial surgical treatment (DAIR or one-stage exchange (OSE)) according to established institutional protocol and followed by 12 weeks of antibiotic therapy, including rifampicin in combination with either fluoroquinolones or minocycline. Clinical and microbiological data were extracted from the hospital registry. Patients were grouped according to antibiotic regimen. The primary outcome was infection recurrence. Secondary analyses included comparison of baseline characteristics, surgical strategy, and microbiological profiles between the groups. Results A total of 271 patients with PJI were included, of whom 213 received a rifampicin/fluoroquinolone combination, and 58 received a rifampicin/minocycline combination. Patients in the fluoroquinolone and minocycline group were similar in age, BMI, and sex distribution. Diabetes mellitus was more frequent in the minocycline group (16/58, 27.6%) than in the fluoroquinolone group (30/213, 14.1%) (p = 0.015). Polymicrobial infections were observed in 44/213 patients (20.7%) in the fluoroquinolone group and 21/58 (36.2%) in the minocycline group. In the minocycline group, 33 (56.8%) underwent DAIR and 25 (43.2%) OSE, compared to 91 (42.7%) and 122 (57.3%) in the fluoroquinolone group (p = 0.055). Recurrence occurred in 18/213 patients (8.5%) and 6/58 (10.3%), respectively. The odds ratio for recurrence was 0.80 (95% CI 0.30–2.12). Conclusion In this large, single-center, retrospective cohort of patients with PJI of hip or knee joint treated with DAIR or OSE, rifampicin combined with fluoroquinolones or minocycline showed comparable recurrence rates, despite differences in baseline characteristics and microbiological profiles. Minocycline seems non-inferior to fluoroquinolones in combination with rifampicin as oral antibiofilm therapy of PJI.