Table 7.

S. aureus (n = 11) andS. epidermidis (n = 3) strains for which the resistance genotype was discordant with the resistance phenotype

Group and strainaProfileMIC (μg/ml)MIC after selectionb (μg/ml)
Group 1
S. aureusR632mecA, Oxas2>64
S. epidermidisR588mecA, Oxas0.125>64
S. epidermidis 184mecA, Oxas1>64
S. epidermidis3348mecA, Oxas0.25>64
S. aureus ATCC 29213mecA negative, Oxas0.50.5
S. aureus18ermC, Erys1>64
S. aureus 75ermC, Erys1>64
S. aureus 93ermC, Erys1>64
S. aureus5919ermC, Erys1>64
S. aureus ATCC 29213ermC negative, Erys0.50.5
Group 2
S. aureus R572mecA negative, Oxar8
S. aureus R620mecA negative, Oxar4
S. aureusR626mecA negative, Oxar8
S. aureus R627mecA negative, Oxar4
S. aureus MA-5091ermABC negative,msrA negative, Eryr>32
S. aureus R566ermABC negative, msrAnegative, Eryr>32
  • a Group 1, resistance gene present, susceptible; group 2, resistance gene absent, resistant. MIC column data for group 1 strains are the initial MICs.

  • b The selection of resistant cells was done by plating on media with increasing gradients of the target antibiotic.