A Cautionary Case for Host Assignment Based on Broad Environmental <i>bla</i> <scp> _OXA </scp> Carriers

genes. Phenotypic testing showed elevated cephalosporin minimal but no carbapenem resistance, consistent with the nature of carbapenem-hydrolysing class D β-lactamases. Our findings reveal that reliance on reference-based metagenomic host prediction can underestimate the diversity of environmental ARG reservoirs. This integrated approach highlights the need for cautious interpretation of metagenomic host assignments and the importance of coupling metagenomic pipelines with culture-dependent validation when assessing ARG ecology in the natural environments.