Molecular epidemiology of OXA-1054, a novel carbapenem-hydrolysing Class D β-lactamase, in Enterobacteriaceae isolated from wastewaters
摘要
Class D carbapenemase-producing Enterobacteriaceae have spread globally in recent decades. The increasing detection of novel variants, often differing by amino acid substitutions or deletions in the β5-β6 loop of OXA-48 or OXA-372 lineages, indicated ongoing dissemination. In this work we describe the molecular epidemiology of a novel OXA-372-like carbapenemase gene, blaOXA-1054, that was identified in Citrobacter, Enterobacter and Raoultella isolates collected from hospital discharges, river water and raw wastewater in Seville, Spain. Cloning of the blaOXA-1054 gene in Escherichia coli confirmed its contribution to carbapenem resistance within the Enterobacterales background. The genetic context of blaOXA-1054 was highly variable, but a conserved backbone, characterized by the IS21 family transposition genes, istA and istB, was consistently present upstream. Frequent co-localization with an ampC gene and heavy metal resistance operons (arsenic and mercury) suggests potential for co-selection under multiple selective pressures. Our study shows that blaOXA-1054 is embedded within a mobile genetic module with strong potential for horizontal transfer, which underscores the importance of monitoring emerging OXA variants in both clinical and environmental settings.