Integral genomic description of bla-harbouring plasmids recovered from Enterobacterales in Argentina.

Objective: To characterise four bla-harbouring plasmids recovered in Enterobacterales isolated in Argentina.

Methods: DNA was sequenced by Illumina and Oxford Nanopore Technologies, assembled using Unicycler, analysed using PlasmidFinder, MOB-Typer, IslandViewer4, and Resfinder, and visualised by Proksee and Clinker. bla-harbouring plasmids were compared with similar deposited plasmids using PLSDB.

Results: Two plasmids belonged to incompatibility group IncFII where bla was located in a previously described genetic context, immersed in an antimicrobial resistance island (ARI). Local IncFII plasmids displayed high similarity (≥90% shared hashes (sh)), with four deposited in PLSDB. The other two local plasmids belonged to the multi-replicon group IncFIB-HI1B, harbouring bla in a novel variant of the genetic context. Both multi-replicon plasmids presented two ARIs, one containing bla in addition to another antimicrobial resistance marker (ARM), and the second ARI carrying bla and a class 1 integron. Plasmids deposited in PLSDB showed low similarity to local multi-replicon plasmids. The most similar plasmids (n = 5) displayed less than 60% shared hashes and showed the same Inc groups but lacked ARM.

Conclusions: This study broadens the limited understanding of bla-harbouring plasmids in Latin America. Furthermore, it represents the first description of bla in a novel variant of common genetic platform and its location in multi-replicon IncFIB-IncHI1B plasmids, which were not previously associated with any ARM.