Wound-associated carbapenemase-producing Gram-negative bacteria in Ireland, 2020-2025: Genomic surveillance of species, carbapenemase mechanisms, and gene location.

OBJECTIVE

To describe the species composition, carbapenemase mechanisms, genomic location, plasmid context, and meropenem susceptibility patterns of wound-associated carbapenemase-producing Gram-negative bacteria (CP-GNB) referred in Ireland.

DESIGN

Retrospective genomic surveillance study.

SETTING

Galway Reference Laboratory Services, a national reference laboratory receiving wound-associated CP-GNB referrals from 23 laboratories across Ireland.

METHODS

We analyzed 69 wound-associated CP-GNB isolates referred to Galway Reference Laboratory Services from 2020 through 2025. Short-read whole-genome sequencing was used for species identification, multilocus sequence typing, carbapenemase detection, plasmid reconstruction using MOB-suite, plasmid replicon typing, and insertion sequence detection. Carbapenemase gene location was classified as plasmid, chromosome, or both. Meropenem susceptibility data were linked and interpreted using European Committee on Antimicrobial Susceptibility Testing clinical breakpoints (version 16.0).

RESULTS

The 69 isolates comprised 13 species/species groups; 59 (85.5%) were Enterobacterales and 10 (14.5%) were non-fermenters. OXA-48-like carbapenemases predominated (34, 49.3%), followed by NDM (18, 26.1%); isolates with carbapenemases from multiple groups accounted for 3 (4.3%). Carbapenemase genes were predominantly plasmid-associated (58, 84.1%). A recurrent carbapenemase-associated plasmid cluster (AA002; IncL) was identified in 24 isolates across 8 species or species groups and 14 referring laboratories. Meropenem susceptibility varied across carbapenemase groups.

CONCLUSION

Wound-associated CP-GNB referred in Ireland represent a diverse surveillance subset in which carbapenemase dissemination is largely plasmid-associated, supporting plasmid-aware, phenotype-integrated genomic surveillance reporting.