TABLE 1

MICs of β-lactam antibiotics against methicillin-resistant S. aureus grown in media with and without NaHCO3a

TreatmentCefazolin MIC (μg/ml)Oxacillin MIC (μg/ml)
MRSA 11/11MW2COLBMC1001300-111MRSA 11/11MW2COLBMC1001300-111
CA-MHB-Tris16825625664326451225616
CA-MHB-Tris + 25 mM NaHCO3485122563243251225616
CA-MHB-Tris + 44 mM NaHCO30.51256256320.5251225632
RPMI 1640 + 10% LB medium1216221164164
  • a MIC values obtained in CA-MHB-Tris for strains MRSA 11/11, MW2, COL, and BMC1001 were within 2-fold of those obtained in standard CA-MHB (see Table S1 in the supplemental material). The MIC values for 300-111 in CA-MHB were 16 and 8 μg/ml for cefazolin and oxacillin, respectively.