Antimicrobial Resistance inEnterococcusspp. of animal origin

Abstract

Enterococci are natural inhabitants of the intestinal tract in humans and many animals, including food-producing and companion animals. They can easily contaminate the food and the environment, entering the food chain. Moreover, is an important opportunistic pathogen, especially the species and , causing a wide variety of infections. This microorganism not only contains intrinsic resistance mechanisms to several antimicrobial agents, but also has the capacity to acquire new mechanisms of antimicrobial resistance. In this review we analyze the diversity of enterococcal species and their distribution in the intestinal tract of animals. Moreover, resistance mechanisms for different classes of antimicrobials of clinical relevance are reviewed, as well as the epidemiology of multidrug-resistant enterococci of animal origin, with special attention given to beta-lactams, glycopeptides, and linezolid. The emergence of new antimicrobial resistance genes in enterococci of animal origin, such as and , is highlighted. The molecular epidemiology and the population structure of and isolates in farm and companion animals is presented. Moreover, the types of plasmids that carry the antimicrobial resistance genes in enterococci of animal origin are reviewed.

Genomic Epidemiology of Vancomycin-Resistant Enterococcus faecium (VREfm) in Latin America: Revisiting The Global VRE Population Structure

“…If our rooting strategy is correct, our results suggest that the animal isolates represent multiple lineages that diverged prior to the emergence of the clinical subclades in the clade A 3 . Importantly, animal-associated branches have significantly lower ampicillin resistance, mutations associated with fluoroquinolone resistance, virulence determinants, and average number of insertion sequences, similar to what has previously reported 41 . Furthermore, the amount of recombination that we found in clade A genomes was greater than previous results.…”

Phenotypic and Genotypic Traits of Vancomycin-Resistant Enterococci from Healthy Food-Producing Animals

“…Using cgMLST indicated that the E. faecalis and the E. faecium isolates belonged to STs typically identified among livestock-associated strains [55]. E. faecium isolated from pigs in this study were represented by a distinct population belonging to ST133.…”

“…These findings suggest a limited potential for transmission of VRE between humans and pigs. Similarly, E. faecium ST310, detected in three poultry isolates, is a poultry-adapted ST that is prevalent among broilers in Sweden [59,60], and E. faecium ST13 and ST157 have been reported in poultry in Sweden, Denmark, and Korea [55]. Taken together, MLST analysis did not reveal any close relationship to typical nosocomial strains belonging to CC17, or to recently emerged endemic strains ST203 and ST796.…”

“…The Tn1546 structures among the enterococci from this study were very similar. The majority contained the G8234T point mutation within vanX, which has been found in enterococcal isolates from healthy and hospitalised humans, in pig isolates, in food isolates, and in environmental enterococci [53][54][55][56]. This indicates that this transposon type is widely disseminated and shared between different enterococcal species and ecological niches.…”

“…Taken together, MLST analysis did not reveal any close relationship to typical nosocomial strains belonging to CC17, or to recently emerged endemic strains ST203 and ST796. Likewise, E. durans is detected frequently in healthy poultry, but is reported only sporadically in human clinical infections [55]. E. durans of human and animal origin have been found to contain similar genetic arrangements of the vanA gene cluster, and it has been shown in vitro that E. durans transfers vanA to human clinical E. faecium at a high frequency [61,62].…”