Emergence of Oxacillin Resistance in Stealth Methicillin-Resistant Staphylococcus aureus Due to mecA Sequence Instability

Richard V. Goering, Erin A. Swartzendruber, Anne E. Obradovich, Isabella A. Tickler, Fred C. Tenover

Research output: Contribution to journalArticle

Abstract

Staphylococcus aureus strains that possess a mecA gene but are phenotypically susceptible to oxacillin and cefoxitin (OS-MRSA) have been recognized for over a decade and are a challenge for diagnostic laboratories. The mechanisms underlying the discrepancy vary from isolate to isolate. We characterized seven OS-MRSA clinical isolates of six different spa types from six different states by whole-genome sequencing to identify the nucleotide sequence changes leading to the OS-MRSA phenotype. The results demonstrated that oxacillin susceptibility was associated with mutations in regions of nucleotide repeats within mecA Subinhibitory antibiotic exposure selected for secondary mecA mutations that restored oxacillin resistance. Thus, strains of S. aureus that contain mecA but are phenotypically susceptible can become resistant after antibiotic exposure, which may result in treatment failure. OS-MRSA warrant follow-up susceptibility testing to ensure detection of resistant revertants.

Original languageEnglish (US)
JournalAntimicrobial agents and chemotherapy
Volume63
Issue number8
DOIs
StatePublished - Aug 1 2019

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Oxacillin
Methicillin-Resistant Staphylococcus aureus
Staphylococcus aureus
Anti-Bacterial Agents
Cefoxitin
Mutation
Treatment Failure
Nucleotides
Genome
Phenotype
Genes

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Cite this

Emergence of Oxacillin Resistance in Stealth Methicillin-Resistant Staphylococcus aureus Due to mecA Sequence Instability. / Goering, Richard V.; Swartzendruber, Erin A.; Obradovich, Anne E.; Tickler, Isabella A.; Tenover, Fred C.

In: Antimicrobial agents and chemotherapy, Vol. 63, No. 8, 01.08.2019.

Research output: Contribution to journalArticle

Goering, Richard V. ; Swartzendruber, Erin A. ; Obradovich, Anne E. ; Tickler, Isabella A. ; Tenover, Fred C. / Emergence of Oxacillin Resistance in Stealth Methicillin-Resistant Staphylococcus aureus Due to mecA Sequence Instability. In: Antimicrobial agents and chemotherapy. 2019 ; Vol. 63, No. 8.
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