The UK Antimicrobial Registry (UKAR): an overview of the first 20 months of recruitment.

Background: The UK Antimicrobial Registry (UKAR) was developed to capture data on real-world usage of recently launched antimicrobial agents. Methods: UKAR is an ongoing prospective registry of adult inpatients prescribed 11 eligible study drugs (cefiderocol, ceftaroline, ceftazidime/avibactam, ceftobiprole, ceftolozane/tazobactam, dalbavancin, delafloxacin, eravacycline, imipenem/cilastatin/relebactam, meropenem/vaborbactam and oritavancin). Data collected from participants' medical records include demographics, infection site, comorbidities, microbiology isolates and susceptibility, treatment regimen and outcomes. Primary outcome is clinical resolution of infection measured 28 days post cessation of study drug. Results: In the first 20 months, 631 participants were recruited, 56% male, with a median age of 60 years. Overall, 44.8% of patients were treated for lower respiratory tract infection, 18.0% for systemic infections including sepsis and 11.1% for urinary tract infection. Comorbidities were common (>90%), 81% of participants had a documented history of resistant organism colonization and only a small proportion of patients received an eligible study drug while in critical care. For Gram-negative agents ceftazidime/avibactam, cefiderocol and ceftolozane/tazobactam predominated, and for Gram-positive agents 94% received dalbavancin. Empirical use was seen in 4.9% of Gram-negative and 66.2% of Gram-positive prescriptions. Where patient outcome was evaluable, infection resolution was seen in 69% and 64% of Gram-negative and Gram-positive participants, respectively. Conclusions: The UKAR provides real-world data on the use of novel antimicrobials confirming they are sometimes used empirically as well as for directed therapy to treat both complex and common infections, and often for multiresistant pathogens. The study is a novel and important resource to support the judicious use of these drugs.