E. coli ST 131 IS ABLE TO ACQUIRE mcr-1 GENE MEDIATED VIA OUTER MEMBRANE VESICLES

LAURA CAMILA CARRERA PÁEZ; MARÍA PAULA QUIROGA; MARTIN OLIVIER; DANIELA CENTRÓN

Buenos aires, CABA

Congreso; Reunion anual de sociedades en biociencias SAIC.SAI.SAFIS. 2020; 2020

Sociedad Argentina de Investigación Clínica

The role of outer membrane vesicles (OMVs) in the evolution to extreme and pandrug resistance in clinical samples is still unknown. That is why we propose to investigate the transmission of the mcr-1 encoding gene through OMVs to the pandemic clone E. coli ST 131. This gene confers resistant to colistin, an antibiotic usually used as last resort in infections associated to multidrug resistant Gram-negative bacteria. First, we isolated and characterized the OMVs from E. coli_mcr-1 that has a plasmid, harboring the mcr-1- genes. The vesicles treated with DNAase were studied and characterized by microBCA, NTA, and TEM. NTA results showed a major peak between 100?200 nm in diameter.These results were confirmed through TEM images. Second, the DNA was purified from the OMVs and used for PCR analysis. Third, these OMVs were used to transform multidrug resistant clinical strain E. coli SM5 belonging to pandemic clones ST131 which harbors pDCAG1 plasmid with the extended-spectrum beta-lactamase blaCTXM-15 gene. The checking of the transfer was performed by colony PCR for the mcr-1 gene of different colonies that grew in plates with 50ug/ml of colistin. Further, gene maintenance experiment was conducted at increasing concentrations of colistin. In the present study for the first time, we characterized OMVs harbouring the mcr-1 gene from E. coli_mcr-1 clinical strain. In addition, the transfer and maintenance of colistin resistance through OMVs to pandemic clone E. coli ST 131 demonstrates the threat of this still not completely studied mechanism of the Lateral Genetic Transfer