Studies of mechanisms of horizontal genetic transfer associated with antimicrobial resistance in a clinical isolate

CARRERA PÁEZ LC; OLIVIER, M; KNECHT C; VARGAS CV; DONIS, N; CENTRÓN D; QUIROGA MP

Congreso; 2nd European Congress on Microbiology |; 2023

Escherichia coli is the most common commensal bacteria in the gut microbiota of both humans and animals. However, this species has developed into a pathogen well adapted to its host causing different diseases. One of these adaptations include the ability to acquire and disseminate multiple mobile genetic elements (i.e., integrons, transposons and plasmids) that confer their phenotypes of antimicrobial resistance (AMR). Some of these mobile genetic elements can be transferred by conjugation, transformation, transduction or via outer membrane vesicles (OMV), the most recently discovered mechanism of Horizontal Genetic Transfer (HGT). Here we study the ability of a resistant E. coli to acquire multiple AMR genes, and to characterize and analyze its OMV as a HGT mechanism involved in AMR dissemination. Here, we use as study model, one of the first E. coli isolates from Argentina with a plasmid harboring the mcr-1 gene that confers resistance to colistin. We studied the ability of this isolate to receive and maintain AMR genes by transformation and conjugation. The acquisition was checked by PCR and antibiotic susceptibility test, and its maintenance was evaluated at days one and 10 after daily subculture. Also, we isolated and characterized the OMVs from this isolate. For that, (i) The source of OMVs was quantitatively defined; (ii) Total quantification of OMVs was made using the Micro BCA Protein Assay Kit; (iii) We obtained images of individual electric vesicles at high resolution using transmission electron microscopy; and (iv) We had evidence of individual particles and its biophysical characteristics by nanoparticle tracking analysis. Finally, the content of these OMVs was evaluated by 2 techniques. First, by PCR assay we looked for mcr-1 gene and confirmed the result by sequencing. Secondly, by Liquid chromatography–MS/MS we studied the proteins that are inside of the OMVs. We found that this isolate acquires and maintains AMR genes, and produce OMV harboring a colistin resistance gene, which may be involved on its HGT dissemination.