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MBio. 2014 Jul 22;5(4):e01386-14. doi: 10.1128/mBio.01386-14.

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

Author information

1
Centers for Disease Control and Prevention, Division of Bacterial Diseases, Respiratory Diseases Branch, Atlanta, Georgia, USA.
2
Division of Scientific Resources, Biotechnology Core Facility Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
3
Minnesota Department of Public Health, Stillwater, Minnesota, USA.
4
New Mexico Department of Health, Santa Fe, New Mexico, USA.
5
Jacobi Medical Center, Bronx, New York, USA.
6
Montefiore Medical Center and Albert Einstein College of Medicine, New York, New York, USA.
7
Centers for Disease Control and Prevention, Division of Bacterial Diseases, Respiratory Diseases Branch, Atlanta, Georgia, USA bbeall@cdc.gov.

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.

PMID:
25053786
PMCID:
PMC4120198
DOI:
10.1128/mBio.01386-14
[Indexed for MEDLINE]
Free PMC Article

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