title: The tyrosine decarboxylation test does not differentiate Enterococcus faecalis from Enterococcus faecium.
abstract: According to the current edition of the Bergey's Manual of Systematic Bacteriology [11] the tyrosine decarboxylation test allows the differentiation of enterococci. Tyrosine is decarboxylated to the biogenic amine tyramine by E. faecalis and not by E. faecium strains. In the present study we sequenced the16S rDNA of two tyramine-producing strains, BIFI-56 and BIFI-58, presumptively classified as E. faecalis. Their 16S rDNA were identical to the same fragment from the E. faecium type strain. Several E. faecium strains were then checked for their ability to decarboxylate tyrosine and also a putative tyrosine decarboxylase-coding gene was PCR amplified from these strains. All the strains confirmed as E. faecium produced tyramine and possessed a DNA fragment coding for a putative tyrosine decarboxylase. The concordance of the two methods allows us to conclude that the tyrosine decarboxylase test cannot be used in the differentiation of E. faecalis from E. faecium since at least some E. faecium strains are tyramine producers.
authors.affiliation: Departamento de Microbiología, Instituto de Fermentaciones Industriales, CSIC, Madrid, Spain.
authors.forename: Angela
authors.initials: A
authors.lastname: Marcobal
authors.forename: Blanca
authors.initials: B
authors.lastname: de las Rivas
authors.forename: Emilia
authors.initials: E
authors.lastname: García-Moruno
authors.forename: Rosario
authors.initials: R
authors.lastname: Muñoz
mesh_terms: D015373:Bacterial Typing Techniques; D004275:DNA, Ribosomal / Q000032:analysis; D013293:Enterococcus faecalis / Q000145:classification* / Q000201:enzymology / Q000235:genetics; D016984:Enterococcus faecium / Q000145:classification* / Q000201:enzymology / Q000235:genetics; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S; D017422:Sequence Analysis, DNA; D014439:Tyramine / Q000096:biosynthesis*; D014445:Tyrosine Decarboxylase / Q000235:genetics* / Q000378:metabolism*
chemical_list: D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D014445:Tyrosine Decarboxylase; D014439:Tyramine