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Polyphyletic emergence of linezolid-resistant staphylococci in the United States

Agnes Wong1, Shilpa P Reddy, Davida S Smyth

  • 1Department of Microbiology and Immunology, New York Medical College, Valhalla, NY, USA.

Antimicrobial Agents and Chemotherapy
|November 26, 2009
PubMed

Insights

Linezolid resistance in Staphylococcus aureus and epidermidis is rare but emerging across multiple genetic lineages. New ribosomal mutations were identified in Staphylococcus epidermidis, suggesting independent evolution of linezolid resistance.

Area of Science:

  • Microbiology
  • Infectious Diseases
  • Genetics

Background:

  • Linezolid is a crucial antibiotic for treating resistant Gram-positive cocci infections.
  • Linezolid-resistant (Linr) Staphylococcus aureus and Staphylococcus epidermidis are currently rare.
  • The genetic diversity and origins of Linr strains remain largely unknown.

Purpose of the Study:

  • To characterize the genetic backgrounds of Linr Staphylococcus aureus and Staphylococcus epidermidis.
  • To identify resistance mechanisms and genetic lineages associated with linezolid resistance.

Main Methods:

  • Sequence-based strain typing was employed.
  • Resistance gene characterization was performed.
  • 46 Linr isolates collected between 2004-2007 were analyzed.

Main Results:

  • Linezolid resistance was observed in at least three clonal complexes of Staphylococcus aureus.
  • Resistance was found in at least four subclusters of a predominant Staphylococcus epidermidis clonal complex.
  • Novel candidate mutations in 23S rRNA and L4 riboprotein were identified in Staphylococcus epidermidis.

Conclusions:

  • Linezolid resistance has emerged independently in multiple clones of Staphylococcus aureus.
  • Multiple clones of Staphylococcus epidermidis have independently developed linezolid resistance through various ribosomal mutations.
  • Understanding these genetic underpinnings is vital for monitoring and combating antimicrobial resistance.

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