Bone infection and inflammation leads to the infiltration of immune cells at the site of infection, where they modulate the differentiation and function of osteoclasts and osteoblasts by the secretion of various cytokines and signal mediators. In recent years, there has been a tremendous effort to understand the cells involved in these interactions and the complex pathways of signal transduction and their ultimate effect on bone metabolism. These crosstalk mechanisms between the bone and immune system finally emerged, forming a new field of research called osteoimmunology. Diseases falling into the category of osteoimmunology, such as osteoporosis, periodontitis, and bone infections are considered to have a significant implication in mortality and morbidity of patients, along with affecting their quality of life. There is a much-needed research focus in this new field, as the reported data on the immunomodulation of immune cells and their signaling pathways seems to have promising therapeutic benefits for patients.

Our aim was to determine the impact of antimicrobial stewardship tools (ASTs) and the COVID-19 pandemic on antibiotic consumption (AC). We used the national software Consores^® to determine AC in DDD/1000 days of hospitalization from 2017 to 2022 in voluntary private hospitals in France. The ASTs considered were: 1. internal guidelines; 2. the list of antibiotics with restricted access; 3. the presence of an antibiotic referent or 4. an ID specialist; and 5. proof of an annual meeting on antimicrobial resistance. Institutions with dedicated units for COVID-19 patients were specified. In 30 institutions, the total AC varied from (means) 390 to 405 DDD/1000 DH from 2017 to 2022. Fluoroquinolones and amoxicillin/clavulanate consumption decreased from 50 to 36 (p = 0.003) and from 112 to 77 (p = 0.025), respectively, but consumption of piperacillin/tazobactam increased from 9 to 21 (p < 0.001). Over the study period, 10 institutions with ≤2 AST had lower AC compared to 20 institutions with ≥3 AST (p < 0.01). COVID-19 units opened in 10 institutions were associated with a trend toward higher macrolide consumption from 15 to 25 from 2017 to 2020 (p = 0.065) and with an acceleration of piperacillin/tazobactam consumption from 2020 to 2022 (p ≤ 0.003). Antibiotic consumption in 30 private hospitals in France was inversely related to the number of AST. The COVID-19 pandemic was associated with limited impact on AC, but special attention should be paid to piperacillin/tazobactam consumption.

Need for parenteral administration and total duration of antibiotic therapy for prosthetic joint infection (PJI) are debated. We report our PJI management, in which outpatient care is privileged. This was a retrospective multicentre cohort study of PJI managed from January 2017 to Jun 2021. Microbial diagnosis was based on surgical samples. Surgical procedures and antibiotic treatments were reported. Chronic PJI was defined by a course >1 month. Oral antibiotic therapy (OAT) was defined by exclusive use of oral antibiotics or by ≤3 days of parenteral treatments. Management failure was defined by clinical and/or microbial relapse of PJI over 24 months after surgical treatment. One hundred and seventy-two patients from 13 institutions were included: 103 were male (60%) and mean age was (±SD): 73 ± 12 years. Sites for PJI were mainly hip (50%) and knee (35%), being chronic infections in 70 cases (41%). The main bacterial genus in monomicrobial infections was Staphylococcus spp. (60%). We recorded 41 (24%) implant exchanges. An OAT was prescribed in 76 cases (44%), and the median (range) course for parenteral route was 6 days (4–180) for 96 cases. Median (range) duration of antimicrobials was 42 days (21–180). Management failure was observed in 7/76 (9.2%) cases treated with OAT and 15/96 (15.6%) treated with prolonged parenteral therapy. In multivariate analysis, risk factors for failure were a knee PJI [adjusted OR (95% CI) = 3.27 (1.27–8.40)] and a polymicrobial infection [4.09 (1.46–11.49)]. OAT for 6 weeks for PJI was associated with a low rate of management failure.