Laverde Gomez JA, van Schaik W, Freitas AR, Coque TM, Weaver KE, Francia MV, Witte W, Werner G (2010): A multiresistance megaplasmid pLG1 bearing a hylEfm genomic island in hospital Enterococcus faecium isolates
Int. J. Med. Microbiol.: Epub Oct 15. doi:10.1016/j.ijmm.2010.08.015.

Enterococcus faecium is considered to be a nosocomial pathogen with increasing medical importance. The putative virulence factor, hyl_Efm, encoding a putative hyaluronidase, is enriched among the hospital-associated polyclonal subpopulation of E. faecium.. The hyl_Efm gene is described to be part of a genomic island and was recently identified to be plasmid-located. Here, we present a description of the structure, localization, and distribution of the putative pathogenicity factor hyl_Efm and its putative island among 39 clinical isolates and elucidate the composition and host range of pLG1, a hyl_Efm multiresistance plasmid of approximately 281.02 kb.

The hyl_Efm gene was located within a 17,824-bp element highly similar to the putative genomic island (GI) structure that had been previously described. This genomic region was conserved among 39 hyl_Efm-positive strains with variation in a specific region downstream of hyl_Efm in 18 strains. The putative hyl_Efm was located on large plasmids (150–350 kb) in 37 strains. pLG1 could be horizontally transferred into four different E. faecium recipient strains (n = 4) but not into E. faecalis (n = 3). Sequencing of pLG1 resolved putative plasmid replication, conjugation, and maintenance determinants as well as a pilin gene cluster, carbon uptake and utilization genes, heavy metal and antibiotic resistance clusters.

The hyl_Efm transferable plasmid pLG1 bears additional putative pathogenicity factors and antibiotic resistance genes. These findings suggest horizontal gene transfer of virulence factors and antibiotic resistance gene clusters by a single genetic event (conjugative transfer) which might be triggered by heavy antibiotic use common in health care units where E. faecium is increasingly prevalent.