Mechanisms of linezolid resistance among coagulase-negative staphylococci determined by whole-genome sequencing

Ryan Tewhey, Bing Gu, Theodoros Kelesidis, Carmen Charlton, April Bobenchik, Janet Hindler, Nicholas J. Schork, Romney M. Humphries

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32 Scopus citations

Abstract

Linezolid resistance is uncommon among staphylococci, but approximately 2% of clinical isolates of coagulasenegative staphylococci (CoNS) may exhibit resistance to linezolid (MIC,≥8 μg/ml). We performed whole-genome sequencing (WGS) to characterize the resistance mechanisms and genetic backgrounds of 28 linezolid-resistant CoNS (21 Staphylococcus epidermidis isolates and 7 Staphylococcus haemolyticus isolates) obtained from blood cultures at a large teaching health system in California between 2007 and 2012. The following well-characterized mutations associated with linezolid resistance were identified in the 23S rRNA: G2576U, G2447U, and U2504A, along with the mutation C2534U. Mutations in the L3 and L4 riboproteins, at sites previously associated with linezolid resistance, were also identified in 20 isolates. The majority of isolates harbored more than one mutation in the 23S rRNA and L3 and L4 genes. In addition, the cfr methylase gene was found in almost half (48%) of S. epidermidis isolates. cfr had been only rarely identified in staphylococci in the United States prior to this study. Isolates of the same sequence type were identified with unique mutations associated with linezolid resistance, suggesting independent acquisition of linezolid resistance in each isolate.

Original languageEnglish (US)
Article numbere00894-14
JournalmBio
Volume5
Issue number3
DOIs
StatePublished - May 13 2014

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Virology

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