vanG element insertions within a conserved chromosomal site conferring vancomycin resistance to Streptococcus agalactiae and Streptococcus anginosus

Velusamy inivasan, Benjamin J. Metcalf, Kristen M. Knipe, Mahamoudou Ouattara, Lesley McGee, Patricia L. Shewmaker, Anita Glennen, Megin Nichols, Carol Harris, Mary Brimmage, Belinda Ostrowsky, Connie J. Park, Stephanie J. Schrag, Michael A. Frace, Scott A. Sammons, Bernard Beall

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23 Scopus citations

Abstract

Three vancomycin-resistant streptococcal strains carrying vanG elements (two invasive Streptococcus agalactiae isolates [GBS-NY and GBS-NM, both serotype II and multilocus sequence type 22] and one Streptococcus anginosus [Sa]) were examined. The 45,585-bp elements found within Sa and GBS-NY were nearly identical (together designated vanG-1) and shared near-identity over an ∼15-kb overlap with a previously described vanG element from Enterococcus faecalis. Unexpectedly, vanG-1 shared much less homology with the 49,321-bp vanG-2 element from GBS-NM, with widely different levels (50% to 99%) of sequence identity shared among 44 related open reading frames. Immediately adjacent to both vanG-1 and vanG-2 were 44,670-bp and 44,680-bp integrative conjugative element (ICE)-like sequences, designated ICE-r, that were nearly identical in the two group B streptococcal (GBS) strains. The dual vanG and ICE-r elements from both GBS strains were inserted at the same position, between bases 1328 and 1329, within the identical RNA methyltransferase (rumA) genes. A GenBank search revealed that although most GBS strains contained insertions within this specific site, only sequence type 22 (ST22) GBS strains contained highly related ICE-r derivatives. The vanG-1 element in Sa was also inserted within this position corresponding to its rumA homolog adjacent to an ICE-r derivative. vanG-1 insertions were previously reported within the same relative position in the E. faecalis rumA homolog. An ICE-r sequence perfectly conserved with respect to its counterpart in GBS-NY was apparent within the same site of the rumA homolog of a Streptococcus dysgalactiae subsp. equisimilis strain. Additionally, homologous vanG-like elements within the conserved rumA target site were evident in Roseburia intestinalis.

IMPORTANCE These three streptococcal strains represent the first known vancomycin-resistant strains of their species. The collective observations made from these strains reveal a specific hot spot for insertional elements that is conserved between streptococci and different Gram-positive species. The two GBS strains potentially represent a GBS lineage that is predisposed to insertion of vanG elements.

Original languageEnglish (US)
Article numbere01386-14
Pages (from-to)1-12
Number of pages12
JournalmBio
Volume5
Issue number4
DOIs
StatePublished - 2014

ASJC Scopus subject areas

  • Microbiology
  • Virology

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    inivasan, V., Metcalf, B. J., Knipe, K. M., Ouattara, M., McGee, L., Shewmaker, P. L., Glennen, A., Nichols, M., Harris, C., Brimmage, M., Ostrowsky, B., Park, C. J., Schrag, S. J., Frace, M. A., Sammons, S. A., & Beall, B. (2014). vanG element insertions within a conserved chromosomal site conferring vancomycin resistance to Streptococcus agalactiae and Streptococcus anginosus. mBio, 5(4), 1-12. [e01386-14]. https://doi.org/10.1128/mBio.01386-14