Reserve antibiotics in paediatrics: single-centre clinical experience and antimicrobial stewardship implementation

This study aims t. o describe the use of WHO Reserve antibiotics in a tertiary paediatric hospital, focusing on our single-centre clinical experience and the implementation of antimicrobial stewardship to optimise their institutional use. We conducted a retrospective observational study including patients under 18 years treated with ceftazidime-avibactam, ceftolozane-tazobactam, cefiderocol, ceftaroline or daptomycin between January 2020 and December 2024. Clinical, microbiological and treatment data were extracted from electronic medical records. Based on these findings, a standardised institutional evaluation framework for Reserve antibiotics was developed and implemented within the antimicrobial stewardship programme. Ninety-six treatment episodes in 76 patients were analysed; most patients (97%) had significant comorbidities, mainly haematological malignancies (79%). Bloodstream infection was the most frequent indication. Prescribing of cefiderocol showed strong concordance with resistance-driven indications, and ceftazidime-avibactam was largely consistent with microbiological criteria. In contrast, ceftolozane-tazobactam and ceftaroline were more frequently used in broader empirical settings. Stewardship measures were subsequently introduced, including formulary restriction, indication-based electronic prescribing tools, and integration of WHO AWaRe classification into the hospital prescribing system.

Reserve antibiotic use in complex paediatric populations highlights the importance of characterizing our clinical experience of prescribing in real-world practice. In this context, the development and implementation of a structured institutional antimicrobial stewardship program represents a pragmatic strategy to improve clinical governance and guide the appropriate positioning of these last-resort agents.

• Reserve antibiotics are critical last-resort therapies for treating multidrug-resistant infections, but their clinical use in complex paediatric populations remains insufficiently characterised in real-world practice. Institutional antimicrobial stewardship programmes are highly recommended to provide necessary oversight and guide the appropriate prescribing of these high-priority agents.

• This study details a comprehensive, single-centre clinical experience of WHO Reserve antibiotic use within a complex tertiary paediatric cohort. Furthermore, we describe the development and practical implementation of a structured institutional stewardship framework-integrating formulary evaluation, electronic prescribing safeguards, and the WHO AWaRe classification-offering a pragmatic model to strengthen local clinical governance and optimise last-resort antimicrobial positioning.