title: Screening of virulence determinants in Enterococcus faecium strains isolated from breast milk.
abstract: In a previous study, the authors isolated lactic acid bacteria from breast milk of healthy mothers. Since some of the identified isolates belonged to the species Enterococcus faecium, the objective of this work was to evaluate their safety. The enterococcal strains were screened by polymerase chain reaction (PCR) and Southern hybridization for the presence of virulence determinants. The potential of the strains to acquire plasmids by conjugation was investigated by screening for genes involved in conjugation processes. Parallel, phenotypic assays were performed. Presence of genes conferring resistance to vancomycin was assessed by PCR. PCR amplifications and Southern hybridizations revealed that all the strains were clear of the majority of potential virulence determinants. None of the strains showed gelatinase activity, hemolysin production, or aggregation phenotype, and none carried the vanA or vanB genes. These findings suggest that milk of healthy mothers may be a source of avirulent E faecium isolates to the newborns.
authors.affiliation: Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Universidad Complutense de Madrid, 28040 Madrid, Spain.
authors.forename: Carlota
authors.initials: C
authors.lastname: Reviriego
authors.forename: Tracy
authors.initials: T
authors.lastname: Eaton
authors.forename: Rocío
authors.initials: R
authors.lastname: Martín
authors.forename: Esther
authors.initials: E
authors.lastname: Jiménez
authors.forename: Leónides
authors.initials: L
authors.lastname: Fernández
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gasson
authors.forename: Juan M
authors.initials: JM
authors.lastname: Rodríguez
mesh_terms: D001483:Base Sequence; D001679:Biogenic Amines / Q000096:biosynthesis; D015139:Blotting, Southern; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D016984:Enterococcus faecium / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D005260:Female; D018093:Gelatinases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008826:Microbial Sensitivity Tests; D008895:Milk, Human / Q000382:microbiology*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D012449:Safety; D020713:Vancomycin Resistance / Q000235:genetics; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics*
chemical_list: D001679:Biogenic Amines; D004269:DNA, Bacterial; D037521:Virulence Factors; D018093:Gelatinases