Comparison of Disk Diffusion and Etest Methods to Determine the Susceptibility of Staphylococcus aureus Circulating in Riyadh, Saudi Arabia to Fusidic Acid

Table 2

Comparison of disk diffusion and proposed MIC interpretive criteria for S. aureus and fusidic acid.

MIC μg/mL	≤0.5 (𝑛=70)	1.0 (𝑛=3)		2.0 (𝑛=4)	≥4.0 (𝑛=45)
Breakpoints proposed by Jones et al. [13]	Susceptible			Intermediate	Resistant
Breakpoints proposed by Skov et al. [10]	Susceptible	Intermediate		Resistant
Disk diffusion result^*	Susceptible		Resistant
zone size (mm)	≥25	25, 26	12	11, 12, 12, 13	≤15

^*The results from disk diffusion are the same using either the EUCAST criteria (≤24 mm =𝑅) or zone size breakpoints by Skov et al. (≤18 mm =𝑅, ≥21 mm =𝑆).