Scope and predictive genetic/phenotypic signatures of bicarbonate (NaHCO3) responsiveness and β-lactam sensitization in methicillin-resistant staphylococcus aureus

Selvi C. Ersoy, Mariam Otmishi, Vanessa T. Milan, Liang Li, Youngju Pak, Jose Mediavilla, Liang Chen, Barry Kreiswirth, Henry F. Chambers, Richard A. Proctor, Yan Q. Xiong, Vance G. Fowler, Arnold S. Bayer

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Addition of sodium bicarbonate (NaHCO3) to standard antimicrobial susceptibility testing medium reveals certain methicillin-resistant Staphylococcus aureus (MRSA) strains to be highly susceptible to β-lactams. We investigated the prevalence of this phenotype (NaHCO3 responsiveness) to two β-lactams among 58 clinical MRSA bloodstream isolates. Of note, ∼75% and ∼36% of isolates displayed the NaHCO3 responsiveness phenotype to cefazolin (CFZ) and oxacillin (OXA), respectively. Neither intrinsic β-lactam MICs in standard Mueller-Hinton broth (MHB) nor population analysis profiles were predictive of this phenotype. Several genotypic markers (clonal complex 8 [CC8]; agr I and spa t008) were associated with NaHCO3 responsiveness for OXA.

Original languageEnglish (US)
Article numbere02445-19
JournalAntimicrobial agents and chemotherapy
Volume64
Issue number5
DOIs
StatePublished - May 1 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmacology (medical)
  • Infectious Diseases

Keywords

  • Antimicrobial susceptibility testing
  • Beta-lactams
  • Methicillin-resistant Staphylococcus aureus
  • Sodium bicarbonate

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