IMPACT OF OUTER MEMBRANE VESICLES IN ANTIMICROBIAL RESISTANCE

CARRERA PÁEZ LC; QUIROGA MP; CENTRÓN D

Congreso; Reunión anual de sociedades en biociencias SAIC.SAI.AAFE.NANOMED.AR; 2024

The outer membrane vesicles (OMVs) are able to harbor genes associated with antimicrobial resistance (RAM). In addition, OMVs possess both defensive and protective functions and thus participate in community related functions. Our goal was to characterize and look for the presence of genes associated with RAM in the OMVs from three relevant resistant strains, E. coli SM5 that belongs to pandemic lineage ST131, E. coli M19736 that harbors mcr-1, and P. aeruginosa PAE981 that belongs to epidemic clone ST2867. In addition, we evaluated if these OMVs could protect other bacteria against a membrane-active antibiotic, such as colistin. To characterize OMVs 1) total quantification of OMVs was performed using the Micro BCA Protein Assay Kit, 2) the images of OMVs was obtain by transmission electron microscopy (TEM), and 3) we estimated biophysical characteristics using nanoparticle tracking analysis (NTA). Finally, by PCR assay we looked for genes associated with RAM. NTA results showed a size between 100–300 nm in diameter. PCR assays allowed us to detect in the OMVs from SM5 the blaCTX-M-15 gene, from M19736 the mcr-1 gene, and from PAE981 the blaVIM-2 gene. Chemical, electro and natural transformation was performed for SM5 using the OMVs from M19736. The colonies obtained were evaluated by PCR for the presence of mcr-1. The three transformation assays with a strain that was previously susceptible to colistin, showed colonies which then were able to survive to this antibiotic without acquiring mcr-1. Therefore, we propose that the OMVs isolated from M19736 could protect SM5 from colistin. The present study shows an efficient isolation method in different bacterial genera that allows the detection of genes associated with RAM by PCR in OMVs. Also, the results obtained indicate that OMVs have a dual impact on the generation of antimicrobial resistance, both through horizontal genetic transfer and through a protective physical effect in clones with epidemic behavior.