Table 1.

Aminoglycoside susceptibility profiles according to the disk diffusion method and MIC results (E-test) for 250 P. aeruginosa isolates (according to CLSI guidelines).15

	Disk Diffusion1			E-test2						MIC 50% (ug/mL)	MIC 90% (ug/mL).
				Resistant			Intermediate	Susceptible
	No. (%) of isolates			MIC(µg/ml)			MIC(µg/ml)	MIC(µg/ml)
	Resistant	Intermediate	Susceptible	–1024128	64–128	16–64	8	2–4	<2
Gentamicin	108(43.2)	8(3.2)	134(53.6)	10	41	49	8	98	44	4	64
Tobramycin	95(38)	7(2.8)	148(59.2)	8	45	37	5	103	52	4	64

				MIC(µg/ml)			MIC(µg/ml)	MIC(µg/ml)		MIC 50% (ug/mL)	MIC 90% (ug/mL).
				>256	–256128	64–128	32	4–16	<4
Amikacin	59(23.6)	7(2.8)	184(73.6)	4	17	32	6	134	57	8	128

1. Zone diameter (mm) for gentamicin and tobramycin, R:<12, I:13-14, S:>15; for amikacin, R:<14, I:15-16, S:>17.

2. MIC breakpoint(µg/ml) for gentamicin and tobramycin, R:>16, I:8; S:<4; for amikacin, R:>64, I:32, S:<16.