Critical-priority Enterobacterales in samples from Procellariiform seabirds: detection of NDM-1 and CTX-M-8...

WHO-designated critical-priority Enterobacterales are increasingly detected beyond healthcare settings, with reports in marine wildlife suggesting broader environmental dissemination and raising potential concerns about wildlife health. Procellariiformes are highly migratory pelagic seabirds and key sentinels of ocean health, yet colonization by these bacteria remains understudied. To address this gap, we evaluated critical Enterobacterales in samples from Procellariiformes admitted to a rehabilitation centre on the southern coast of Brazil.

Thirty-one Enterobacterales isolates, pre-selected based on β-lactam resistance from the CePRAM/R3 animal culture collection, were retrospectively analysed and characterized phenotypically and genotypically. Among these, 17 (54.8%) met WHO critical-priority criteria. Fifteen were resistant to third-generation cephalosporins, with frequent detection of blaCTX-M-1 and co-resistance to quinolones, aminoglycosides, and tetracyclines. Two isolates (Enterobacter roggenkampii and Escherichia coli) produced NDM-1 and underwent whole-genome sequencing; both carried blaNDM-1 on an IncA/C2 plasmid and had extensive resistomes. The E. coli co-produced NDM and CTX-M-8 and encoded a broad virulence repertoire consistent with an APEC-associated genotype. In silico analyses revealed determinants associated with heavy metal, biocide tolerance, and osmotic and ionic stress responses, suggesting genomic potential for persistence in saline and contaminated environments. Three host species carrying critical-priority Enterobacterales are currently listed as threatened, underscoring conservation and One Health concerns.

The detection of critical-priority, virulent Enterobacterales among pre-selected resistant isolates from Procellariiformes supports their relevance in One Health surveillance, while also highlighting potential risks to threatened hosts. These findings support integrated One Health surveillance and mitigation efforts spanning wildlife, marine environments, and human activities.