Molecular diversity and transferability of the tet

Authors: Lucia Rizzotti Federica La Gioia Franco Dellaglio Sandra Torriani

Publish Date: 2009/03/31

Volume: 96, Issue: 1, Pages: 43-52

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Abstract

In the present study 20 enterococci belonging to the species Enterococcus faecalis 12 strains Enterococcus faecium 4 Enterococcus durans 2 Enterococcus hirae 1 and Enterococcus mundtii 1 and originating from a total production chain of swine meat commodities were analysed to investigate the diversity of their tetracycline resistance gene tetM PCR–RFLP and sequence analysis showed that the tetM gene of most strains can be correlated with the Tn916 transposon Conversely tetM of six E faecalis and the E hirae strain all isolated from pig faecal samples may be associated with previously undescribed members of the Tn9161545 transposon family In vitro filter conjugation trials showed the ability of 50 of the enterococcal strains including E mundtii to transfer the tetM gene and the associated Tn916 and new transposons to E faecalis or Listeria innocua recipient strains tetM gene transfer to L innocua recipient was also directly observed in meat food products Collectively these sequence and conjugation data indicate that various transposons can be responsible of the spread of tetracycline resistance in enterococci and validate the opinion that Enterococcus species are important sources of antibiotic resistance genes for potentially pathogenic bacteria occurring in the food chainWe thank E Lavarini for her technical assistance and P S Cocconcelli Istituto di Microbiologia Università Cattolica del Sacro Cuore Piacenza Italy for providing the strain E faecalis OG1RF This research was partially supported by the Fondazione Cassa di Risparmio di Verona Vicenza Belluno e Ancona Italy

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