Bioinformatic assessment of the pathogenic potential of non-Enterococcus faecalis and non-Enterococcus faecium strains isolated from food products

LECHNER, MARCUS; TERAN, LUCRECIA C; BONACINA, JULIETA; SAAVEDRA, LUCILA

Mar del Plata

Congreso; IX Congreso Argentino de Bioinformática y Biología Computacional; 2018

Enterococci are widely distributed in nature, and may be associated with dairy and other fermented food products. Since 1970´s, some strains of this genus have emerged as important nosocomial pathogens, possessing many virulence factors. This fact has raised concerns about the risks for spreading potentially virulent strains, and about their ability to exchange virulence and drug resistance genes with pathogenic strains outside hospital environments, especially via the food chain. Most of the studies carried out to date have been focused on E. faecium and E. faecalis. In light of these circumstances, the present work aimed to evaluate, by a bioinformatic approach, the pathogenic potential of enterococcal strains isolated from food products, or from food related sources, not belonging to the E. faecalis and E. faecium species. In this way, the genomes of 24 enterococcal strains, from 12 different species, were analyzed in search of virulence determinants and sequences related to mobile genetic elements. Their isolation sources encompassed: cheese, cultured milk, beef carcass, chicken carcass rinse, pork chop, fermented sausage, drinking water, among others; and their genome sizes were between 2.3 Mb and 4.6 Mb, with GC contents ranging from 35.1% to 40.4%. As a result of the functional annotation of the enterococcal genomes via the Rapid Annotation Subsystem Technology server, it was observed that excluding two E. durans strains, all enterococci under study had coding sequences (CDS) related to sex pheromones, implicated in potential horizontal gene transfer; meanwhile none of the strains included CDS in the ?Quorum sensing and biofilm formation? subsystem. E. rotai LMG 26678 and E. thailandicus DSM 21767 were the only ones with CDS assigned to the ?Listeria Pathogenicity Island LIPI-1 extended? subsystem. Likewise, only the strains isolated from water had CDS (3 in total) allocated in the subsystem ?VraSR and LiaSR two-component regulatory systems?, of the regulation of virulence subcategory; also present in E. faecalis V583, a vancomycin-resistant strain derived from a bloodstream infection. Finally, PEGs associated to vancomycin resistance were found in E. ureilyticus. Therefore, in order to reliably assess the pathogenicity of the studied strains, functional analyses must be carried out.