Abstract Background Children with cancer are at high risk for infection and frequently require antimicrobials. Antimicrobial stewardship (AMS) interventions can mitigate toxicity and development of antibiotic resistance yet the pharmacy and infectious diseases specialists who usually perform AMS are often absent in global settings. We report our experience testing a novel intervention to shift the antibiotic timeout to nurses in six pediatric oncology units in Central America. Methods The Nurse-initiated Antibiotic Timeout (NATO) is a scripted conversation between nurses and physicians to reevaluate antibiotic appropriateness after 48 to 72 hours of empiric use for febrile neutropenia. First, we performed a baseline assessment of AMS capacity using the WHO Practical Toolkit for AMS Programmes checklist. Based on these results, sites tailored a generic implementation plan emphasizing educational and documentation tools and iterative PDSA (Plan-Do, Study-Act) cycles to improve implementation and effectiveness outcomes. Results All sites collected antimicrobial use data for a minimum of two months. Four sites then piloted NATO, producing change ideas, including changes to documentation tools, antimicrobial decision categories, communication processes, and times. From August 2022 – October 2023, NATO was performed in 53.4% of febrile neutropenia episodes in the three sites reporting data. Sites had substantial NATO performance rate variation from month to month. Sites reported changes in antimicrobial therapy in 47% of episodes after a 6-month period (Figure 1). Conclusion The difference in performance rate of NATO underscores the importance of real-time reporting to adjust AMS implementation strategies. The change ideas developed by each site differed, however, core tools emerged, which will support AMS in other global settings. Next steps include comparing antimicrobial use pre- and post-intervention and determining a sustainability and scalability plan. Figure 1. Incidence of change in antibiotic therapy over time.