Cefiderocol-resistant Aeromonas with expanded Resistomes in German hospital wastewater: Phenotypic and genomic evidence from the environment–clinical Interface

Hospital wastewater is a key interface between clinical and environmental reservoirs of antimicrobial resistance, fostering selection and horizontal gene transfer. Aeromonas spp. are aquatic opportunistic pathogens with highly plastic genomes and are increasingly recognized as potential intermediaries in resistance dissemination. We compared 72 cefiderocol-selected Aeromonas isolates recovered from untreated hospital wastewater collected at six tertiary care hospitals across Germany with 62 clinical isolates from patients with intestinal and extraintestinal infections, to characterize cefiderocol susceptibility, resistome composition, and genomic mobility features. Pangenome analysis revealed an open genome structure comprising 21,364 gene clusters, with a core genome of 2486 genes and a large cloud gene pool (15,612 clusters present in