TABLE 1.

Representative MIC values against colistin-resistant clinical isolates^a

Strain	MIC (μg/ml)
	CST	PMB	TGC	CAZ	FEP	ATM	MEM	AMK	LVX	NIT
E. coli 08-85	8	8	0.25	0.5	32	64	≤0.03	4	32	64
E. coli 13-43	8	8	1	2	8	64	≤0.03	4	64	128
E. coli 13-66	8	8	1	2	4	16	≤0.03	2	64	128
E. coli 13-68	8	8	0.5	1	8	4	≤0.03	32	8	128
E. coli H67	4	4	0.25	64	128	64	4	2	16	256
K. pneumoniae 09-20	16	16	2	1	0.5	0.5	≤0.03	>1,024	32	256
K. pneumoniae H04	32	32	1	>256	8	32	2	256	32	≥512
E. cloacae D01	256	256	2	256	2	64	1	2	0.125	64
E. cloacae L09	32	32	1	>256	32	64	4	16	32	256
E. cloacae R31	64	128	0.5	1	0.064	64	1	2	1	64

^aCST, colistin; PMB, polymyxin B; TGC, tigecycline; CAZ, ceftazidime; FEP, cefepime; ATM, aztreonam; MEM, meropenem; AMK, amikacin; LVX, levofloxacin; NIT, nitrofurantoin. According to CLSI supplement M100 (28th edition), breakpoints for resistance are listed as follows: CST/PMB/MEM, 4 μg/ml; LVX, 8 μg/ml; CAZ/FEP/ATM, 16 μg/ml; AMK, 64 μg/ml; NIT, 128 μg/ml (27).