INTRODUCTION: Bacteremia caused by Gram-negative bacilli places a substantial burden on healthcare systems, mainly due to antibiotic resistance and delays in administering appropriate antimicrobial treatment (AT). The aim of this study was to describe the implementation of a rapid detection test (RDT) for CTX-M Extended Spectrum Beta-Lactamase-producing MATERIAL AND METHODS: A cross-sectional study was conducted on blood culture (BC) samples from adult patients (≥18 years) admitted to a tertiary hospital in Spain (January 2021-February 2024). BCs with confirmed RESULTS: A total of 250 BCs from 250 patients were included. Empiric antimicrobial treatment (EAT) had not been prescribed in 41/250 (16.4%) patients, but was appropriately initiated in 33/250 (13.2%) after notification of the RDT results. Among those already receiving EAT (209/250, 83.6%), inappropriate and appropriate actions in AT were observed in 18/250 (7.2%) and 191/250 (76.4%) patients, respectively. By the time routine AST results were available, 241 (96.4%) patients had received appropriate treatment. CONCLUSIONS: This study demonstrated the real-world application of an RDT to detect CTX-M ESBL directly from BC in a tertiary hospital. Early reporting of CTX-M ESBL status in