Background: Recent studies have shown that mammalian milk represents a continuous supply of commensal\r\nbacteria, including enterococci. The objectives of this study were to evaluate the presence of enterococci in milk of\r\ndifferent species and to screen them for several genetic and phenotypic traits of clinical significance among\r\nenterococci.\r\nResults: Samples were obtained from, at least, nine porcine, canine, ovine, feline and human healthy hosts.\r\nEnterococci could be isolated, at a concentration of 1.00 Ã?â?? 102 -1.16 Ã?â?? 103 CFU/ml, from all the porcine samples and,\r\nalso from 85, 50, 25 and 25% of the human, canine, feline and ovine ones, respectively. They were identified as\r\nEnterococcus faecalis, Enterococcus faecium, Enterococcus hirae, Enterococcus casseliflavus and Enterococcus durans.\r\nAmong the 120 initial enterococcal isolates, 36 were selected on the basis of their different PFGE profiles and further\r\ncharacterized. MLST analysis revealed a wide diversity of STs among the E. faecalis and E. faecium strains, including\r\nsome frequently associated to hospital infections and novel STs. All the E. faecalis strains possessed some of the\r\npotential virulence determinants (cad, ccf, cob, cpd, efaAfs, agg2, gelE, cylA, espfs) assayed while the E. faecium ones only\r\nharboured the efaAfm gene. All the tested strains were susceptible to tigecycline, linezolid and vancomycin, and\r\nproduced tyramine. Their susceptibility to the rest of the antimicrobials and their ability to produce other biogenic\r\namines varied depending on the strain. Enterococci strains isolated from porcine samples showed the widest spectrum\r\nof antibiotic resistance.\r\nConclusions: Enterococci isolated from milk of different mammals showed a great genetic diversity. The wide\r\ndistribution of virulence genes and/or antibiotic resistance among the E. faecalis and E. faecium isolates indicates that\r\nthey can constitute a reservoir of such traits and a risk to animal and human health.
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