Delafloxacin in Bone and Joint Infections: A Multicentre Retrospective Study

Introduction & Aim Delafloxacin is a novel fluoroquinolone with enhanced activity against Gram-positive pathogens, including isolates with reduced susceptibility to other fluoroquinolones. Despite this favorable profile, there is limited clinical data to assess its efficacy in bone and joint infections (BJIs). Methods We conducted a retrospective, multicenter, descriptive study across eight French hospitals. All adult patients treated with delafloxacin for at least seven days for a BJI between January 2022 and March 2024 were included. Data on patient demographics, infection characteristics, microbiology, treatment rationale, and outcomes were collected. Results Forty-one patients were included. The median age was 67 years, and 90% had significant comorbidities. Prosthetic joint infection (PJI) was the most common diagnosis (67%), followed by fracture-related infection (12%) and osteomyelitis (12%). Staphylococci caused 98% of infections, with 90% resistant to conventional fluoroquinolones. The primary reason for delafloxacin use was treatment simplification, especially in polymicrobial infections (41.5%). At one year, the clinical cure rate was 56%. All treatment failures (n = 14) occurred in patients with orthopedic implants, primarily in acute postoperative settings. Over 50% of failure cases involved isolates with a delafloxacin minimum inhibitory concentration (MIC) ≥ 0.094 mg/L. Adverse events attributable to delafloxacin occurred in 7 patients (17%), leading to discontinuation in all cases. Conclusion In this real-world cohort, delafloxacin was primarily used to simplify complex BJI treatment regimens. It demonstrated potential in managing infections caused by fluoroquinolone-resistant staphylococci. However, a higher risk of failure was observed in cases involving orthopedic implants and when the causative pathogen had an elevated MIC. These findings suggest that delafloxacin may have a role in BJI therapy, but its use should be cautious in device-related infections.