Antimicrobial Resistance and Virulence Genes inEnterococcus faeciumandEnterococcus faecalisfrom Humans and Retail Red Meat

Abstract

The emergence of antimicrobial-resistant and virulent enterococci is a major public health concern. While enterococci are commonly found in food of animal origin, the knowledge on their zoonotic potential is limited. The aim of this study was to determine and compare the antimicrobial susceptibility and virulence traits ofEnterococcus faecalisandEnterococcus faeciumisolates from human clinical specimens and retail red meat in Slovenia. A total of 242 isolates were investigated: 101 from humans (71E. faecalis, 30E. faecium) and 141 from fresh beef and pork (120E. faecalis, 21E. faecium). The susceptibility to 12 antimicrobials was tested using a broth microdilution method, and the presence of seven common virulence genes was investigated using PCR. In both species, the distribution of several resistance phenotypes and virulence genes was disparate for isolates of different origin. All isolates were susceptible to daptomycin, linezolid, teicoplanin, and vancomycin. In both species, the susceptibility to antimicrobials was strongly associated with a food origin and the multidrug resistance, observed in 29.6% ofE. faecalisand 73.3%E. faeciumclinical isolates, with a clinical origin (Fisher’s exact test). Among meat isolates, in total 66.0% ofE. faecalisandE. faeciumisolates were susceptible to all antimicrobials tested and 32.6% were resistant to either one or two antimicrobials. InE. faecalis, several virulence genes were significantly associated with a clinical origin; the most common (31.0%) gene pattern included all the tested genes excepthyl. In meat isolates, the virulence genes were detected inE. faecalisonly and the most common pattern includedace,efaA, andgelE(32.5%), of whichgelEshowed a statistically significant association with a clinical origin. These results emphasize the importance ofE. faecalisin red meat as a reservoir of virulence genes involved in its persistence and human infections with reported severe outcomes.