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

UNLABELLED: 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. CONCLUSION: 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. WHAT IS KNOWN: • 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. WHAT IS NEW: • 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.